Subido por Raúl Armando Ramírez Nieto

Biological Study Metodology

Biological Study Methodology
8 DE ABRIL DE 2020
Mexican regulations for animal experimentation (NOM-062-ZOO-1999) ........................................ 3
History of Animal Experimentation: .................................................................................3
Animal Experimentation in Mexico: .................................................................................5
Important Points: ............................................................................................................6
Euthanasia:.................................................................................................................... 14
Bioethical Problems: ...................................................................................................... 14
Methodologies for planning experiments. .................................................................................... 16
2.1 Experimentation. .............................................................................................................. 16
Experimentation as a Process: ...................................................................................... 17
Control Problems in Experimentation and Validation. .................................................... 18
Definition of Variables. .................................................................................................. 18
Experimental Designs .................................................................................................... 19
Acquisition of Biologic Variables: Trajectories and position, study of morphologies, study of
mechanisms and functions. .......................................................................................................... 21
Trajectories and position. .............................................................................................. 21
Study of Morphologies .................................................................................................. 21
Study of Mechanisms and Functions. ............................................................................. 22
BIBLIOGRAPHY: ............................................................................................................................ 23
Biological Study Methodology
In the history of humanity, our species has always been dependent on other organisms, either
for cattle, clothing, agriculture, transportation, hunting, etc. It's not surprising make the
statement that without animals, society as we know, would be different or inexistent, just by
the simple fact that in modern times we still use them for the same purposes as in the past
because they're essential for the economy and growth of a country, but not limited only for
these activities, animals nowadays they're used in the pharmaceutical, cosmetic and scientific
industry, commonly as test subjects.
In the last decade, we saw different organizations against animal cruelty more active than
ever, taking a most assertive posture in terms of animal experimentation, even with the public
declaring that they're uncomfortable buying products or affiliate with brands who use
marsupials, rodents, chimpanzees, rabbits or another specimen known by its terrible and
extensive use within their white-clean rooms, making them suffer in a meaningless way or
putting an enormous amount of stress.
So it is correct to assume that it is necessary the action of organizations like PETA ensures
the rights for the tests animals, government action to apply laws of regulation, talks of animal
cruelty awareness and educate the youngest ones about the key roles that play every animal
on earth.
In Mexico exists a normative that regulates these practices known as the: "Mexican
regulations for animal experimentation (NOM-062-ZOO-1999)", putting valid cases in
which cases it is correct the use of animals and what methods for experimentation are valid
to obtain the best results with the lowest discarded assets in an ethical way, applied to every
research facility, Institutes, and education centers, all of it regulated by this norm of the
These experimentations can be used to obtain the reaction and the effects of a new drug, the
behavior of subjects under certain circumstances of stress, habitat or environment, the study
and behavior of a subject with a certain disease, to obtain mechanical variables of certain
species in order to mimic it, enhance it or putting it in another mechanical system; test new
cosmetic products that can be harmful to human skin, etc.
Whoever, even with those facts, in this country exists a global concern about its natural
habitats and how they are being reduced drastically due to corruption and private interest,
and it´s a global concern because this country it`s one of the seventeen megadiverse countries,
housing a 10% of the world registered wildlife, most of them endemics. Within animal
exploitation, exists a huge number of cases of animal cruelty of domestic animals and animals
used for test cosmetic products by national and international entities taking advantage of
loopholes within this Mexican normative.
Mexican regulations for animal experimentation (NOM-062-ZOO-1999)
History of Animal Experimentation:
Old Ages:
First of all, we need to get into the context of what it has been this practice before modern
times, and surprisingly we can trace the animal experimentation back in the ancient Greek
civilization. Where it first appears the one who's considered the first biologist experimenter
named Acmeaon of Crotona, with Hippocrates teachings and his famous bisection who gave
a pig tinted water to see the action of swallowing. Aristoteles (384-322 b.C.) wrote an
encyclopedia in which describes all that he knows with citations of the basis of the validity
of animal experimentation and others like, Herophil and Erastrastrates, whom back in the
great city of Alexandria existed, they prof de difference between tendons, muscles, and the
nerves. Even we can find Greek archives of early essays of toxicology tested.
Much of these practices were elevated and imposed among the educated and the church.
Generations after generation treated these studies as definitive, such as the practices made
from Galen (130 – 210 a.D. ), who it is known by doing dissections on various animal species
among the public serving the function of education and, his studies about the function of the
lungs, the heart's blood vessels and the nerves that came from the brain and spinal cord.
The Middle Age:
This era of history it's known by the step-back that humanity took, it can be justified by
religion due to they saw wrong the dissection of any living or dead creature, and practicing
it was considered heresy by the catholic church, just some places like the Salerenitan School
of Medicine practiced scientific-based medicine in the centuries IX and XII, testing their
knowledge inherited by Galen and practiced in the pig, "The most human-like creature".
But in Asia things were different, in China, Chao-Fu was known as the first veterinarian with
degree, using medicinal plants, acupuncture and some others external procedures, even
veterinarians traveled from Korea and Japan to China in order to study horse acupuncture,
even forming the first school for horse doctors, in Osaka, Japan.
The Buddhist and Hindu religions, their historic importance in this period, based on the
philosophy of any living creature has the same value as others, as also every living creature
are susceptible to the pain, not like Catholic Church and to some extent the Muslims, that
their way of thinking very living creature except for humans, don't feel pain due to lack of
The Renaissance:
In the Renaissance, it was born a new wave of thinking named curiosity and like a disease, it
spread to the educated, royal families, artists, and even the common people has it. Science
and medicine saw a golden age within this two periods, trying to understand the different
functions of organs and tissues, and they do so first with the use of corpses, a thing that would
be penalized by the church before, but the researchers saw a problem, what will happen when
there are no more corpses, so they started using animals once again even more if they wanted
to study living tissue.
English philosopher, Francis Bacon, declared that the use of animals is vital for science to
move forward due to the high correlation of mammals in how the organs work. Meanwhile,
William Harvey in his work: Exercitatio anatomica de Motu Cordis et Sanguis in animalibus,
established a more proper way of how the circulation of blood occurs, thanks to the
experiments conducted by him.
The Illustration:
In this period, all progress achieved in the renaissance was enhanced, but also the ethical
problems of this methodology starts to spread, touching topics like the suffering of animals
in the pursuit of knowledge.
For Edmund O'Meara the practice of bisection generates suffer to all individuals involved in
the experiment, generating an anti-naturalism state for both, the perpetrator and the victim of
the experiment. This was new for the scientific community, making such a bold statement
made some to rethink of what is correct, others justifying the use of them, even claiming that
it is an exaggeration for the activist group to suggest self-regulation.
During this period, happened one of the most important things ever occurred in the history
of medicine, in 1798 result from seizures of a cow infected with smallpox, a doctor is driven
by its curiosity and fascination of how some of the rural people who work with these animals
were unharmed by this disease, his name was Edward Jenner and he created the vaccination,
and in these centuries we saw the golden age of medicine with the creation of drugs and new
methods of medical diagnostic, obviously tested in animals.
In 1825, Charles Darwin, tried to promote the “Act of animal cruelty” in the British
parliament, one of the first official laws that regulates the animal testing, but make no
mistake, Darwin was okay with animal experimentation if, the purpose it’s the elaboration of
scientific thesis and not just mere curiosity.
At this point in history, thanks to the discovery of the anesthesia in the XX century, the
number of experiments with animals grew up, thanks to the properties of anesthesia, that
made the vivisection of the animal more ethical and painless. But also legislations to regulate
the use of animals in experiments, due to lack of legal limits and the creation of terms like
animal welfare and declaration of animal rights, to maintain a moderate and conscious use of
this creatures
XXI – Present Times:
Nowadays the use of animals it’s been more controversial than ever, creation of laws in all
around the globe in pro of animal rights, strict regulations even banning test and
experimentation of cosmetic products on animals in places like the European Union, Canada,
India, Norway, New Zealand, Israel and South Korea.
Laws like the “Good Laboratory Practice” and “Animal Welfare” in the USA, Cruelty to
animal Act in the UK, “Ethical Principles and Guidelines for Scientific Experiments on
Animals” in Switzerland, promote the searching of new methodology for animal
experimentation, there is the importance of the new breakthroughs in genetic engineering,
biotechnology and in vitro experimentation.
Animal Experimentation in Mexico:
In Mexico the use of animals has always been a controversial theme, due to traditions and us
of them, so it is fair to say that experimentation is no strange in terms of controversy either.
In Mexico exists an Animal Welfare legislation, that includes the Federal Animal Health Act
and the General Wildlife Law, these laws protect and grant rights to all animal that are present
in the Mexican territory, and by no means this excludes the laboratory animals.
And thus the Official Mexican Norm NOM-062-ZOO-1999, containing the basis of animal
care in experimentation, reproduction, how to acquire them, how to establish a proper use of
them, how they need to be treated in the most humanitarian way, and how and when to use
euthanasia. This norm requires that every institution counts, with capable personnel, certified
laboratories and more important requirements like the participation of a medic veterinarian
as the general manager.
And also requires the participation of various several ministries, like The General Health
Law in Health Research Matters, who is responsible of compliance in avoiding as much as
possible the suffering of any animal in a laboratory, as equal in his death in every experiment
or research, or the Ministry of Agriculture, Livestock, Rural Development, Fishing and Food
who is responsible of the expedition of animal health measures in verify and certify the
compliance of the animal health measures; and to guarantee of the production, health
protection and good use of every animal in the laboratory.
Important Points:
This normative is conceived by 15 points, and here, is the most relevant of the norm (This
points appear in order and with the same number as in the original document):
1. Objectives and application fields.
This point establishes that every laboratory in the Mexican Republic has to follow the
Norm with the objective of establish and uniform specifications for production, care
and use of the animals of laboratory for every physical and moral person with a
relation with the following animals (Table 1.a).
Table 1. All Bioteries who experiment with these animals are obliged to follow the Norm.
Carnivores :
rats, mice, guinea pigs, hamsters and gerbils.
Cats and Dogs.
Non-Human Primates.
The Ministry of Agriculture, Livestock, Rural Development, Fishing and Food and
the General Directorate of Animal Health are responsible for compliance and
observation of this norm.
2. References.
This norm has to follow other norms related to animal rights and security protocols
needed to the correct function of the laboratories, these norms can be englobed in the
following scheme (Esquema 1):
Laboratory Animals:
• NOM-003-ZOO-1994: Criteria for the operation of approved
testing laboratories in animal health matters.
• NOM-029-ZOO-1995: Characteristics and specifications for
facilities and equipment for testing and / or analysis laboratories in
animal health matters.
• NOM-033-ZOO-1995:Humanitarian sacrifice of domestic and wild
• NOM-046-ZOO-1995:National Epidemiological Surveillance
• NOM-051-ZOO-1995: Humanitarian treatment in the mobilization
of animals.
• NOM-087-ECOL-1995: Establishes the requirements for the
separation, packaging, storage, collection, transport, treatment and
final disposal of biological-infectious hazardous waste.
• NOM-008-SCFI-1993: Mexican Official Standard General System
of Measurement Units.
• NOM-018-STPS-1993: Recquisition of characteristics like the
services of showers, changing rooms and lockers in the workplace.
• NOM-028-STPS-1994:Safety-Color code for the identification of
fluids conducted in pipes.
Figure 1. Objectie Clasification of the norms.
3. Definitions and Abbreviations.
In this part of the norm, we appreciate the use of scientific terms that are important to
minimize confusion between terms and guarantee the correct use of them. In this list
of terms, one stands out the most in the entire standardization: Bioterio, that basically
refers to all laboratories who kept animals for experimentation during one or more of
the phase of their life (birth, development, reproduction and death).
4. General Dispositions.
The institutions who work with animals need to have certified Bioterios, this
guarantee a good quality of work and preservation of the laboratory animals, this
means that all laboratories, requires a veterinarian with experience in medicine and
animal science in laboratories.
The bioterio not only need a veterinarian, it also needs an Intern Committee for the
Care and use of Animals, to ensure the correct following of every protocol present in
this Norm, Technical Staff, required to maintain a proper function to every aspect in
the laboratory, meaning that they need certain experience and knowledge in fields
like anatomy, physiology, chemistry, metrology, etc.
Every Animal acquired needs a certificate of precedence where establishes
microbiologic and genetic status, health conditions, as well as identification data like:
Name, address and company name of the provider.
File number that is granted by the notification of operation notice.
Animal species to which the certificate refers.
Race, strain.
Total number of animals.
Sex, indicating the quantity of each one.
Date of birth, when known.
Laboratory and / or cabinet tests, including the date of the last
performance to determine the microbiological status when required.
i) Name and signature of the Veterinary Zootechnician certified in
laboratory animals that endorses the certificate.
Not only that, also every institution where animals are used for experimentation,
needs to ensure that their habitats are clean at every time, every animal needs a clean
and balanced diet (the diet needs to be must be free of additives, drugs, hormones,
antibiotics, pesticides and contaminants, not past the expiration date and stored in a
clean ventilated room), programs that prevents diseases, as well continuous
observation with the objective to find changes in the animal’s behavior.
Also the animals need identifications, the identification and application places can
be different in every species (Figure 2. ID on a rat), the identifications can be:
ID Cards: assigned to every anima in their box or cage.
Natural Marks: These are considered only if the characteristic can be
traceable without confusion.
Dyes or tincture: used as a temporal identification within 20 days.
Perforations and Notches.
Earrings: placed in the ears of the rats, mice and porcine, the material
can be plastic or metal.
Tattoo: Can be placed in different parts of the body according the
Subcutaneous Transmitters: the only method that can be used in all
the species.
Figure 2: Areas where it can be Placed an Identification form in a mouse. Red: Dye or Colorants; Blue: Dye
or Colorants; Black: Tattoos and Earrings.
5. Animals covered by this Standard.
This point of the norm covers the animals that are recognized for experimentation
under this standard, how they need to be threated, diet, medical care, space required,
in other word, satisfy physiological needs.
o Rodents: in the case of rodents the equipment designed to host these animals,
must be designed for the good caretaking of the animal, giving an adequate
space to free movement and adoption of normal postures for the species, also
this area needs to be resistant to continuous cleaning, the spaces assigned must
be accordingly to the species and its weight.
Every one of the species within the rodent class must be separated from others
with different microbiologic conditions. Also the food and water of these
animals must be accessible for them.
The cages with solid floor where the rodents are place need to contain a bed
that guarantee the urine absorption, excrement and water wasted. Tthis class
of animals must be placed in groups where the space is limited by the
following specifications: Animal, Weight (g), Floor Area per Animal (cm2),
Height from the floor to the roof of the cage (Table 2).
Table 2. Minimum space for Rodents living in laboratories maintained in
o Lagomorphs: for this class of animals it’s only contemplated the Rabbit. As
well as the rodents, the cages of these animals must be in good quality, this
cages must provide the basic needs of the individual, also, it is required to
have the sufficient width and height for the free and natural movements of the
Every new animal has to be in a period of quarantine, if an exemplar presents
symptoms of sickness, must be diagnosed, treated and retrieved from the
The diet of a rabbit must cover the minimum of these nutritional requirements
on the stages of growth, pregnancy and lactation (Table 3):
Table 3. Minimum Requirements Of Alimentation
Raw Protein
Raw Lipids
Raw Fiber
No less than 16.0 %
No less than 2.5%
No less than 14.0 %
Mo more than 8.0 %
At least but not less important the manipulation of the rabbit must be realized
by qualified personnel, by supervision of the Medic Veterinarian responsible.
o Carnivores: this class of animal only contemplates dogs and cats, within the
norm, the hosting of these animals must be in cages, either individual or
collective, this cages must have the following dimensions (Table 4), these
individual cages must contain a place for drinking water, dinner plate and
adequate conditions for cleaning and disinfection.
Table 4. Minimum Space Recommended for Cats and Dogs.
Corporal Weight Area
Of Height (cm)
Hasta 30
Like every other animal, mentioned before, they need to be in good shape,
meaning they to be cleaned, vaccinated against rabies and have a balanced
diet, all this accordingly to the age and physiological state of the animal, also,
manipulation and restraint techniques that are carried out with dogs and cats
must supervised by the responsible Veterinary Doctor.
o Non-Human Primates: the care of these animals it’s more complicated due of
tenacity and intelligence of these animals, also the measures to protect their
psychological stability, have the same priority as those concerning their physical
Each individual needs between 0.063 and 0.163 m3/kg of space in their cages, this
cages need to be wide and tall provisioning an adequate space for free movement,
normal postures and behavior adjustments, one of the important things is trying to
mimic the habitat behavior of the subject was originally from, if not, this can affect
in a terrible way the subject.
For the animal management, the primate cages must be equipped with a compression
system providing a better form to inject the animal.
6. Facilities.
The installations must be designed for the necessities of the users, experimental
subjects and personnel, with defined sectors: Animal Housing Sector,
Experimentation Sector and Support Operations. These Facilities can be Indoors or
a) Indoors Installations: All bioterios that are in interior enclosures, may be built
in a segment, wing, level or physical space of the building or land of the
b) Outdoors Installations: Outdoors Bioterios can be pens, grasslands, etc. They
are the common method for housing animals and are accepted by the norm, but
these installations must cover: protection against extreme temperatures and other
adverse weather conditions.
These two types of installations must count with:
- Location: These areas are destined to hosting animals and must be placed as an
independent form from occupied from humans.
- Animal Areas: Basic sectors that ensures the animal hosting, physical separation
of species and experimentation (Scheme 3).
- Specifications of sanitary finishes: These areas must be provided with sanitary
finishes that primarily favor hygiene as a means of preventing or spreading a
8. Experimental Techniques.
1) Analgesia and anesthesia
This technique is used in case the animal suffers mores pain than the procedure
like an injection, marking or perforation. The drug used in this practice it is total
responsibility of the researcher, this drug can be freely chosen, with exception of
muscle relaxants or any paralyzing drugs due to this two kinds of drugs are not
It is recommended the supply of tranquilizers, analgesics and anticholinergics
before the anesthetic.
2) Administration of fluids and substances.
The general administrations of fluids and substances must be done according to
generally accepted clinic and scientific practices, where the animal is immobile
(Table 5).
Table 5. Routes Of Administration Of Fluids And Substances
** NOTE:
+ Allowed
- Not Allowed
Figure 3.Scheme of Animal Areas; A) Reception Area; B)Rooms for the production and maintenance of
animal; C) Room of Multiple Uses, c.e) Area exclusively Outdoors; D)Support Areas ;
In this point describes us the applied procedures applied in scientific researches to kill in the
most humanitarian way an animal, with the purpose of eliminate or minimize the amount of
stress, pain, emotional disturbance and suffering during a procedure.
These procedures must be applied accordingly to federal laws; the selection of the methods
need to include certain compatibility with the purposes of the experimental protocol, also the
she selection of the protocol is total responsibility of the researcher or/and the veterinarian.
The selection criteria of the euthanasia methods need to be:
 Induce the unconsciousness of animals in a minimum time.
 Induce death without producing signs of panic.
 Have compatibility with the requirements and purpose of the study.
 Have a minimal environmental impact.
And also the selection and application of the methods need to be applied accordingly to the
highest ethical principles.
Application of the technique:
1. Use Tranquilizer, analgesics or immobilizing drugs, when the capture or
immobilization causes pain.
2. No other animals should be present unless groups that are going to be sacrificed at
the same time.
3. In the euthanasia of cats and dogs, the treatment must be benevolent.
4. After the euthanasia, it´s necessary the confirmation of the animal’s death.
The personnel who conducts his technique must be properly trained and had experience on
the normal behavior of the species who is going to be euthanized and how this affects the
Some of the recommended methods can be inhalable agents, non-inhalable agents or physical
methods, the convenience of every one of these drugs it depends on the brevity between the
moment it is applied and the moment when unconsciousness is inducing (Scheme 4).
Bioethical Problems:
It is well known that Mexico has terrible levels of corruption, and if we’re talking about
animal exploitation is the same, is known that Mexico host 10% of the registered wildlife of
the word, and also that Mexico is the third largest cosmetic manufacturer in the world, but
this “achievement” is product of once again, corruption.
Cosmetics companies from all around the globe test their products here, due to the lack of
enforcement of the norm(NOM-064-ZOO-1999), or even taking advance of legal holes of
the same.
“In Mexico there is a disaster, in fact, they come from other countries to experiment here
because there is no law , because there is no regulation that prevents animals from being used
in the cosmetic industry, what could be more banal than killing or mistreating to an animal to
make a ‘lipstick’?” –Ricardo Monreal, Senaor of Morena
With these words, Mexico seeks to be the second country in America Latina banning any
experimentation with animals for cosmetic practices. Under this normative (NOM-064-ZOO1999), government branches, federal laws and various animalistic parties back had their first
approach to the ban on animal experimentation back in 2019, trying to follow the examples
like the European Union, Canada, India, Norway, New Zealand, Israel and South Korea.
Accordingly, to the European Comission, more than 15,000 ingredients have been tested, so
it’s unnecessary more experiments with these animals.
•Anesthetic Eter.
Nitrogen and
Derivatieves of
•Chloral hydrate.
•Use of Nicotine.
•Head Concussion.
•Animal Drowning.
Figure 4. We got an example of valid Methods to induce Euthanasia, In blue are the valid
and most commonly used Methods, in Orange are the methods than can be approved by a
committee under supervision, Also we have the inadmissible methods, due to unnecessary
amount of pain and stress.
Methodologies for planning experiments.
Experimentation is based on the analysis of casualty, and implies the manipulation of
situations where subjects face, by definition, experimentation consists in a set of activities,
executed under a certain action (Kepel,1991).
There are 2 types of experimentation the classic keep everything constant except the variable
of interest and the modern, consists in an experience planned in advance, meaning that is an
active form to access information where certain variables are manipulated to examine its
influence over other variables, it is important that the researcher is who establishes the levels
of the low control variables, avoiding free flux.
Some advantages of the experimentations are a higher probability to obtain a desired effect,
also, the control and variation in it, can modify the conditions to study the same situations
maintaining and removing the aspect under study.
But, some of the biggest criticisms of the experimentations, is that the real world passes to a
second plane because experimentation does not represent a real-world situation, due to the
fact that some factors are fixed, other problem, is the difficulty of the experimental design.
Higher probability to
obtain a desired
Difficulty of
experimental design.
Can modify the
High time cost.
Random assignation
of subjects to
different conditions
of the experiment.
the eexperiment is
far from reality.
A higher exposure of
different conditionss.
Figure 5. A) Advantages of the experimentation; B) General Critiscisms of exerimentation.
Experimentation has two focuses, generalization focus and focus in the theoretical
explanation of the experiment trying to describe the effects that appear in a given situation,
trying to make it as analogous as possible to the real situation.
Experimentation for theoretical explanation allows us to know the reason for certain
behaviors. It is necessary to have a theory that allows us to explain the phenomenon and,
then, develop the appropriate experiment and contrast this theory.
These two types of experimentation differ in the existence or not of a theoretical construction
that is intended to be tested and that determines the design of the experiment.
Another two types of experimentation are:
Field Experimentation: These experiments occur in real scenarios and the nonmanipulative factors are discarded.
Laboratory Experimentation: These experiments try to create an artificial situation
adequately for the development of an experiment.
Experimentation as a Process:
1. The Experimentation begins with the foundation of
the hipothesis.
2. Operationalize the hypotheses on a set of variables
and select the appropriate experimental design.
3. Experiment Realization and Data Collection.
4. Statistical analysis of the data is based on the
comparison of the mean values in the experiment.
5. Obtaining the conclusions of the study.
Figure 6. Experimentation Process.
2.3) Control Problems in Experimentation and Validation.
The main concern in the experimentation development consists in the control of errors that
can be present, in order to mitigate its effects.
The control can be achieved by a correct design of the experiment, using statistic
techniques that can provide a better control the additional effects, these techniques of
control principally includes random assignation of individuals, rotation of treatments
to avoid problems. The execute of controls in the whole process of the experiment
contributes to its validity. The control is an indispensable requirement in order to
achieve intern validity, for that reason it is more present in laboratory experiments
than in field experiments.
There are two types of validation:
o Intern Validation: is a precision measurement of the experiment, so other
explications in the experiment, except of the hypothesis gets discarded, this
also means, that the effect in the dependent variable have been caused by the
independent variables in the most part.
o Externa Validity: alludes the fact that the results on the study can be
generalized to a certain group
In the validation process, if exists the interest of prove more intern validation, this
implies to apply a stricter controls meaning spend more time in the laboratory at the
same time implying an elevated confinement of the real world and a low external
validation. Also is worth mentioning that a low internal validation means also a low
external validation
2.4) Definition of Variables.
A) Independent Variables:
Those aspects controlled by the researcher on the development of the experiment on the ones
who assume that are the causal agent, those are the independent variables. This control can
be done by pure measurement, and the reason for that it´s because the variable cannot be
manipulated or the manipulation was not contemplated.
The normal thing to do is use three independent variables, the reason is that is hard to explain
a concept cannot be expressed in a sole effect by one independent variable, also is uncommon
that experiments use only one variable.
B) Dependent Variables.
This variable is also known as the criteria variable, it is the variable that measures the
variation of the principal concept of the experiment, the one that is affected by the treatments
and other independent variables, also, it allows us deduct one process of the different status.
In the experimentation process the most recommended approximation is using diverse
dependent variables (the number of these dependent variables largely dependent on
investigator risk aversion), that show us different result patterns as a result of the variations
on the independent variables.
C) Exogenous variables
The Exogenous or external variables are those who tend to deviate the study objective. These
variables can influence in the impact on the independent variable over the dependent variable,
meaning that it can occur the observable changes in the dependent variable are not produced
by an independent variable.
There are also error variables, are unnoticed, are unknown and are not measured, however,
they can cause changes in the dependent variable that, in the eyes of the researcher,
2.5) Experimental Designs
To classify an experiment design, the first thing to ask is if all the conditions are random, if
the answer is yes we face a pure experiment, on the contrary, the next question is if it exists
multiple experiments, and again, if the answer is yes, we are talking about a quasiexperiment.
A quasi-experiment, is the study where the variables cannot be controlled by the researcher
and works with natural or intact responses, also this kind of experiment does not adjust to the
minimal requirements of the pure experiment due to the impossibility of randomly assign the
conditions of treatment and obtain all the possible alternatives. In the Table 6 are the main
And thus for a pure Experiment, the most common designs use multiple groups or factorial
designs. The notation for describe this methods is the observation o measurements of the
dependable variables and are represented by Oi, and the treatments are presented like Xi.
𝑋1 𝑂1
𝑋2 𝑂1
Where 𝑋1,2 represents the treatments possible, and 𝑂1 is the observation of the dependent
variable that the experiment is realized.
In these kind of design is complicated to assume that the obtained data corresponds to reality
due to lack of control.
Another model can be multiple group design pretest-postest, which allow us know if the
groups were initially similar in terms of the observed variable and know the increments of
the same. This model is useful when there is no group control.
𝑂1 𝑋1 𝑂2
𝑂1 𝑋2 𝑂2
𝑂1 𝑋3 𝑂2
𝑂1 𝑋𝑛 𝑂2
In other hand the data analysis can be analyzed in two ways, one can be analyze the change
on the dependent variable that is produced in every treatment:
𝑂1 − 𝑂2
Generating one sole punctuation for treatment.
Table 6. Difference Between a Quasi-Experiment an Pure Experiment.
Sample Definition
Assignation by groups
Assignation by groups
External Variable Control
Internal Variable Control
Measurement Level
Must Accomplish
Not necessary.
Acquisition of Biologic Variables: Trajectories and position, study of
morphologies, study of mechanisms and functions.
Trajectories and position.
When we are thinking about trajectories and position of biologic variables, it is necessary to
identify our variable of interest it can be an angle, velocity, or displacement, as an example
the position angles of the arm when it moves, but how it can be analyzed? One way to do it,
is finding a similar system that behaves in a similar way to our biologic system, in the case
of the “arm movement” we have an analog system known as the “double pendulum”.
Figure 7. Double pendulum System and it is behavior of one mass of the system.
Once the system is chosen, the analysis of the system should be easier if we trace the
movement of one of the two points across time, and try to explain this behavior in a
mathematical way, like an equation represented in a plane and also there are some apps like
Tracker that allow us to see the angle behavior just using a video.
Study of Morphologies
The Morphology, a branch of biology that studies characteristics like anatomy, shape and
appearance, as can been noticed, these characteristics are outwards characteristics of an
organism, to do this, the most important thig is to identify the most prominent feature in the
species of interests, also, morphology can be studied on a smaller scale (cell types). The
ability to compare two organisms through morphology is a necessity for every researcher.
Comparative Morphology has helped us because when we compare organisms, we learn more
of them, and those with more similar morphology are the most closed related, and as a result
from this, anatomical similarities and differences it makes possible stablish the classification
of organisms.
Also, a good example of the use of morphology can be seen in the paper “Morphological
Feature Extraction for the Classification of Digital Images of Cancerous Tissues” by JeanPierre Thiran and Benoît Macq, where it presented a new method for recognition of
cancerous tissues automatically, based on the shape and size of the observed cells.
In this paper, in the experimentation every image was obtained by biopsy using tissues of the
lungs and digestive tract, and to obtain these images the technical equipment used for the
image acquisition were a high optical scope and a CCD B/W camera.
Other experiments like lotus flower, in which they try to mimic the hydrophobic properties
of the flower, and this property is generated due to leaves have nanostructures on their
surfaces that are coated with hydrophobic wax crystals, and to do this morphology is the key
aspect of this experiment.
3.3) Study of Mechanisms and Functions.
A living creature have several mechanisms that allows its existence, but first what is a
biological mechanism. A biological mechanism allow the correct function of certain
organism within certain conditions and limits, these conditions can be external or internal.
Some mechanisms can be the respiratory mechanism; this mechanism allow the gas exchange
with the medium, but how does it work, we know the route that the air has to follow in the
human body and how does it work in a cellular way.
But thanks to science and technology we now have equipment that can provide more
information in chemical mechanisms as seen in the Figure 8.
•Measures the electrical activity of the heartbeat.
•This measurement can provide information on the frequence that can be
signs of dissease.
•Shows a continous X-Ray image transmited to a monitor.
•It can be used to view the gastrrointestinal tract, visualize blood vessels
and Organs.
Computed Tomography
•Provides a differen form of imaging known as cross secional imaging.
•It can detect different tissues in a "slice", this method is used for the
search in coon cancer.
Nuclear Magnetic Resonance
•This method can Provide a ful 3D imaging
•With this instrument a electromagnetic wave is produced across time in a
rotationary way, allowing to se with detail tissues, metal concentrations,
Figure 8.
Ruiz de Maya, Salvador & López, Inés. (2013). Metodología del Diseño Experimental.
"Biology: Comparative Morphology: Studies of Structure and Function ." Scientific Thought:
Context .
Thiran, J. P., & Macq, B. (1996). Morphological feature extraction for the classification of
digital images of cancerous tissues. IEEE Transactions on biomedical engineering, 43(10),
Prado, M., & Daniel, J. (2016). Perspectivas de la Experimentación Animal en Ciencias
Biomédicas (1.a ed.,
Fluoroscopy. (2019, junio 14). Recuperado 8 de
What is Computed Tomography? (2017, diciembre 5). Recuperado 8 de abril de 2020, de
Suárez, C. (2015). Maltrato animal en México: la otra cara de la crísis del respeto a la vida. Tercera
Morales, P. (2019). México busca convertirse en el segundo país en América Latina en
prohibir las pruebas cosméticas con animales. RT en Español. Retrieved 5 April 2020, from
Miguez, M., Largo, J., & Perez, M. (2016). Perspectivas de la experimentacion animal (1st
Vilches, L., & Zurita, M. (2014). LA EXPERIMENTACIÓN ANIMAL [Ebook] (pp. 15-40).
Garibay, M. (2020). Mexican Senate passes bill to outlaw cosmetic animal testing - Humane
Society International. Humane Society International. Retrieved 4 April 2020, from
Gil, G., & Rodriguez, X. (2019). Bioterios en México: 20 años de caos y riesgos.
Romero Herrera, T. A., & Hernández-Navarro, M. D. Actividad antioxidante in vitro e in
vivo del extracto acuoso de pérsimo (Diospyros kaki L.), maracuyá (Passiflora edulis var
Sims) y flor de jamaica (Hibiscus sabdariffa L.).
DIARIO OFICIAL. (2001). NORMA Oficial Mexicana NOM-062-ZOO-1999,
Especificaciones técnicas para la producción, cuidado y uso de los animales de
laboratorio. (Primera
S. de Aluja, A. (s. f.). Animales de laboratorio y la Norma Oficial Mexicana (NOM-062ZOO-1999).
Marczyk, G., DeMatteo, D., & Festinger, D. (2005). Essentials of research design and
methodology. John Wiley & Sons Inc.
Coral Moncayo, H. E. (1998). Utilización de métodos experimentales y de simulación
numérica para la microzonificación sísmica de áreas urbanizadas en Andorra. Universitat
Politècnica de Catalunya.
Blackburn, H., Keys, A., Simonson, E., Rautaharju, P., & Punsar, S. (1960). The
electrocardiogram in population studies: a classification system. Circulation, 21(6), 11601175.
Paul T. Callaghan. (1993). Principles of nuclear magnetic resonance microscopy. Oxford
University Press on Demand. Paul T. Callaghan. (1993). Principles of nuclear magnetic
resonance microscopy. Oxford University Press on Demand.
Smyth, D. H. (1978). Alternatives to animal experiments. Scolar Press Ltd..