Veterinary Medical Applications
Lesson Title: Reproduction
TEKS Addressed in Lesson:
130.6. (c)(6)(D)
130.6. (c)(4)(C)(D)
130.6. (c)(13)(F)
Lesson Objectives:
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Students will identify the anatomical parts of both the male and the female reproductive systems as well as
recall the function of each
Describe the processes of fertilization and embryonic development
Discuss reproductive diseases and disorders
List gestation lengths and reproductive behaviors for various domesticated animals
Explain the process of artificial insemination and explain the benefits
Key Terms/Vocabulary
Bladder-the organ in the body that holds urine after it passes through the kidneys and before it leaves the body
Cervix- a sphincter muscle that serves to join the vagina to the uterus. Fills with a mucosal plug during gestation and
stretches during parturition to allow fetus to pass through.
Cowper’s glands- either of a pair of small glands that open into the urethra at the base of the penis and secrete a
constituent of seminal fluid.
Epididymis-a system of ductile emerging from the posterior of the testis that holds sperm during maturation and that
forms a tangled mass before uniting into a single coiled duct which is continuous with the vas deferens
Estrogen- any of a group of steroid hormones that promote the development and maintenance of female characteristics
of the body
Estrus- a recurring period of sexual receptivity and fertility in many female mammals; heat
Fallopian tubes-(in a female mammal) either of a pair of tubes along which eggs travel from the ovaries to the uterus
Gestation- the process of carrying or being carried in the womb between conception and birth; period of pregnancy
Gonadotropin- any of a group of hormones secreted by the pituitary that stimulate the activity of the gonads
Hormone-natural substance that is produced in the body and that influences the way the body grows or develops
Ovaries-a female reproductive organ in which ova or eggs are produced, present in humans and other vertebrates as a
pair
Oviduct- a tube that allows for the passage of eggs from an ovary
Penis- the copulatory and urinary organ of the male mammal
Progesterone- a steroid hormone released by the corpus luteum that stimulates the uterus to prepare for pregnancy
Prostate- a gland surrounding the neck of the bladder in male mammals and releasing prostatic fluid
Rectum-the final section of the large intestine, terminating at the anus
Retractor muscle- retracts the penis into is preputial sheath
Scrotum- tissue that surrounds the testicles, is essential in temperature regulation of sperm
Seminal vesicles- each of a pair of glands that open into the vas deferens near its junction with the urethra and secrete
many of the components of semen
Testis-The testicle is located outside the body cavity in the scrotum and has two vital functions: producing the
spermatozoa, and producing the male hormone, testosterone
Testosterone- a steroid hormone that stimulates development of male secondary sexual characteristics, produced
mainly in the testes, but also in the ovaries and adrenal cortex
Ureter-duct that carries away the urine from a kidney to the bladder or cloaca
Urethra- the tube through which urine moves from the bladder and out of the body and that in men and male animals is
also the means by which semen leaves the body
Uterine horns- serve as the egg’s pathway from a fallopian tube to the uterus
Uterus-the organ in the lower body of a female mammal where offspring are conceived and is the site of embryonic
development for most mammals
Vas deferens- a sperm-carrying duct especially of a higher vertebrate that in the human male is a thick-walled that
begins at and is continuous with the tail of the epididymis and eventually joins the duct of the seminal vesicle to form
the ejaculatory duct
Interest Approach/Anticipatory Set:
-Show teacher presentation, “Interesting Breeding Behavior.” Presentation includes facts about animal behavior during
the reproductive process.
-Display the reproductive tracts to be dissected later in the lesson.
Teaching Plan and Strategy Presentation of New Material
Teacher PowerPoint that defines the function of each of the female and male reproductive tracts (see terms list above),
the reproductive process and differences amongst several mammalian and avian species and diseases or complications
associated with reproduction.
PowerPoint: Reproductive Physiology
Sexual reproduction is the union of sperm and egg. Two parents are required. Most animals are produced with sexual
reproduction.
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Sperm is the sex cell of male animals, produced in the testes.
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Egg, or ovum, is the sex cell of female animals, produced in the ovaries.
Fertilization is the process by which the union of sperm and egg occurs. It is also known as conception.
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Insemination is the union of sperm and egg; occurs in the female reproductive tract.
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After fertilization, the embryo attaches to the uterus for nourishment, develops as a fetus until it can
live outside uterus, then it’s born.
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Natural Insemination: When male and female mate, sperm is placed in the female’s reproductive tract
by copulation, or the mating process. Females are only receptive to males during the time in the estrous
cycle known as heat.
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Artificial Insemination: Placing semen collected from a male in the female reproductive tract with
special equipment. Must be done when the female is in heat.
The condition of an animal based on its age and sexual condition. Includes animals that are both capable and incapable
of reproduction.
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Animals can be made incapable of reproduction by removing the ovaries or testes or altering the
condition of the reproductive organs.
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Castration: removal of testes from the male. Management process used on young male animals,
promotes growth and development in more desirable ways.
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Neutering: process of making female incapable of reproduction. Ovaries of the female removed to
render female incapable of reproduction.
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Also known as spaying
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Neutering also refers to male castration sometimes.
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Reproductive development of males and females follows fairly definite stages.
Prepuberty: The stage of a young animal before it is capable of reproduction. Sufficient development
has not been reached for animal to reproduce
Puberty: The stage when an animal reaches a level of
reproduction.
sexual development where it is capable of
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Females: Estrous cycle results in release of mature eggs that can support mating, conception
and gestation.
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Males: Can produce viable sperm.
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Age of puberty varies with species, nutrition and health condition.
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Cattle (8-12 months)
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Sheep (5-7 months)
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Swine (4-7 months)
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Horses (12-15 months)
Mating behavior
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Males develop libido (desire to mate) and social status
Females are receptive to mating during heat
Gestation: Period when female is pregnant. Length varies with species
Parturition: Process of giving birth. Hormones are produced to support process and prepare for lactation.
Lactation: The secretion of milk by the mammary glands of females, initiated by hormone activity. Lasts for
several months following parturition.
Male Hormones
Gonadotropic Releasing Hormone (GnRH) – Hormone that stimulates the gonads.
Follicle Stimulating Hormone (FSH) – Causes production of sperm cells.
Luteinizing Hormone (LH) – Causes endocrine cells in the testes to produce the male hormone – testosterone.
Testosterone – The steroid hormone responsible for the growth and development of secondary sex characteristics in a
male such as growth and maintenance of male sex organs and the production of sperm.
Hypothalamus – Area of the brain directly above the pituitary that produces one of the hormones which control
reproduction Gonadotropic Releasing Hormone (GnRH).
-Pituitary – Gland situated beneath and stimulated by the hypothalamus, releases follicle stimulating hormone (FSH)
and –Luteinizing hormone (LH), which serve such functions as stimulating production of sperm and testosterone in
males.
Female Hormones
Gonadotropic Releasing Hormone (GnRH) – Hormone that stimulates the gonads. It also acts as a light switch turning
FSH and LH on and off through the negative feedback system. (Released by the Hypothalamus)
Follicle Stimulating Hormone (FSH) – Signals the follicle on the ovary to begin production of an egg. (Released by the
Anterior Pituitary).
Luteinizing Hormone (LH) – Causes the follicle to undergo changes which lead to egg release. (Released by the Anterior
Pituitary).
Estrogen – As the follicle grows larger, it begins to secrete more and more estrogen. This hormone affects the nervous
system causing restlessness, the desire to mount other animals. It is the hormone that causes the signs of heat and it
causes the female to accept service from the male. (released by the follicle)
Progesterone – The yellow body, which is the new gland formed by the collapsed cells of the follicle, secretes this
hormone. It is the hormone that maintains pregnancy. It prepares the uterus for pregnancy and prevents the heat
cycle.
Discuss artificial insemination, the justification for artificial insemination as well as the benefits.
Advantages of AI:
1. Genetic improvement through more accurate evaluation of transmitting ability of males, continued after the
death of the male
2. Use of semen from genetically elite sires increases the accuracy and intensity of selection
3. Control of venereal or other diseases
4. Improved record keeping on farms where used
5. More economical than natural service when genetic merit is considered
6. Safer by the elimination of dangerous bulls on the farm, especially for the dairy breeds
Disadvantages of AI include the amount of time livestock managers must spend checking females for estrus. Some
special facilities for corralling and insemination are required. Trained personnel are required to perform the technique.
Activity/Application/Student Engagement/Laboratory
Label the female and male reproductive tracts, in addition, students should research the function of each part and
briefly explain the function of the each part. (Approximately 25 minutes)
After completing the male and female reproductive diagrams, show students a photo of the avian reproductive systems.
Have students identify differences and make inferences based upon differences in anatomy. Discuss the process of egg
development. (5-8 minutes)
Laboratory- Reproductive tract visual and dissection (approximately 25 minutes)
In groups of no more than 5, students should use a teacher prepared lab sheet to assist in locating each part of the tract
and use dissection pins (straight pins) to label the parts of the female reproductive tract. After identification of parts,
and definition of function, students should dissect the tract in order to find the cervix and examine the interior portion
of the tract and the ovaries.
Evaluation/Summary
Student Discussion
Lab activities
Reproduction Quiz (see below)
Animal Reproduction Quiz
1. ____stretches allow baby to pass at birth
a. ovulation
2. ____release of an egg from the ovary
b. cervix
3. ____temperature regulation and protection of testicles
c. estrogen
4. ____act of mating between animals
d. scrotum
5. ____causes female to go into estrus
e. copulation
6. Dystocia is trouble giving birth.
True
or
False
7. Progesterone controls sex drive of animals.
True
or
False
8. The larger the animal the earlier they reach puberty.
True
or
False
9. Urethra is only found in females.
True
or
False
10. Position of the fetus stays the same during gestation.
True
or
False
11. A male animal with one fertile testicle is a _____________.
A. free martin
B. cryptorchid
C. monorchid
D. none of these
12. ______________ do not show any visual signs of estrus.
A. cattle
B. dogs
C. horses
D. sheep
13. Which of the following animals’ testicles are held in the body cavity?
A. birds
B. fish
C. reptiles
D. horses
C. April 30
D. April 15
C. embedding
D. budding
14. When should a heifer bred on July 1 give birth?
A. April 10
B. April 1
15. A tadpole develops into an adult frog by the process of
A. fertilization
B. metamorphosis
16. A __________ is a fertilized egg.
17. A filly typically reaches maturity at __________ months of age.
18. __________________ of sperm are produced by the testicles.
19. What does IVF stand for? __________________________________
20. A zygote ______________ repeatedly to become an embryo.
21. Name an animal that is a seasonal breeder.
_____________________
22. List three signs of estrus. ______________________________________________
23. What is needed for reproduction/fertilization to occur? _____________________________
24. Name three reproductive hormones.
_______________________________________
25. Female farm animals have _____ ovaries and the ___________ animals only have one functional ovary.
References/Additional Materials/Extended Learning Opportunities/Enrichment
Cornell Veterinary Medicine resources
http://peer.tamu.edu/VBB/AgTeacherResources.asp
http://www.myimsservices.com
Merck Veterinary Manual
College and Career Readiness Standards:
Science
VI. A-VI. G
developed by Jennifer Jackson, Frisco Centennial HS, Frisco, TX
under contract with the Texas Education Agency, Educational Excellence Project for AFNR
managed by the Department of Agricultural Leadership, Education & Communications,
Texas A&M University
Copyright © Texas Education Agency 2013