Animal, Plant

1
Animal, Plant Soil Science

• Lesson C4-1
• Anatomy and Physiology of
• Animal Reproductive Systems

2
Interest Approach

• Ask students to name a car part. Make a list on
  the chalkboard. Ask students to briefly explain
  each parts function in the operation of the car.
  Then ask students why it is important for a car
  mechanic to be able to identify and know the
  function of the parts. After a brief discussion,
  ask students if it is important for a livestock
  producer to know the parts of an animal. If so,
  why?

3
Objectives

• Identify the male reproductive organs and their
  functions in mammals.
• Identify the female reproductive organs and their
  functions in mammals.
• Define and explain the steps of spermatogenesis
  and oogenesis, and describe sperm and egg
  characteristics.

4
Objectives

• Identify the male and female reproductive organs
  and their functions in poultry.
• Describe the methods used to castrate and neuter
  animals, and explain the benefits of castration
  and neutering.
• Explain the phases of reproductive development in
  the life of an animal, and determine an animals
  readiness for breeding.

5
Terms

• alimentary canal
• bladder
• castration
• cervix
• clitoris
• cloaca
• copulation
• cowpers gland
• epididymis

• fallopian tubes
• fertilization
• follicles
• funnel
• gametes
• gestation
• incubation
• infundibulum
• isthmus

6
Terms

• labia majora
• labia minora
• lactation
• magnum
• mucosal cells
• neutering
• oogenesis
• ova
• ovary

• oviducts
• papilla
• parturition
• penis
• prostate gland
• puberty
• scrotum
• semen
• seminal vesicles

7
Terms

• sheath
• spawning
• spaying
• sperm
• spermatogenesis
• spermatozoa
• testicles
• testosterone

• urethra
• urine
• uterine horns
• uterus
• vagina
• vas deferens
• vulva
• zygote

8
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• To have a successful livestock operation, a
  producer must have an understanding of the
  various reproductive organs
  and their functions.
• In most cases, a livestock
  operation will have only a
  limited number of males available for breeding.
• The male reproductive system contains several
  interconnected parts that must all work together
  for successful mating.

9
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• Some of the major organs found in the male mammal
  reproductive system are
• A. TesticlesThe testicles produce sperm, the
  male sex cells (also called spermatozoa).
• They also produce a hormone called testosterone
  that causes the appearance and behavior of the
  animal to be masculine.
• Two testicles are present in male mammals.

10
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• B. EpididymisThe epididymis is the storage site
  for sperm cells.
• From the testicle,
  these cells enter the
  epididymis to mature.
  
• Sperm can fertilize a
  females ova (female
  sex cell) as
  it travels
  through the epididymis.
• A separate epididymis
  is attached to each
  testicle.

11
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• C. ScrotumThe scrotum is a two-lobed sac that
  contains and protects the two testicles.
• It also regulates the temperature of the
  testicles, which is lower than the body
  temperature.
• When the environment temperature is low, the
  scrotum contracts, pulling the testicles toward
  the body and its warmth.

12
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• When the environmental temperature is high, the
  scrotum relaxes, permitting the testicles to drop
  away from the body.
• Maintaining the correct temperature is critical
  because extreme temperatures (too hot or too
  cold) can affect the production and vitality of
  sperm.

13
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• D. Vas deferensThe vas deferens is essentially a
  transportation tube that carries the
  sperm-containing fluid from each epididymis to
  the urethra.
• E. UrethraThe urethra
  is a large, muscular canal
  extending from the urinary
  bladder.
• Both semen and urine move through the urethra to
  the end of the penis.

14
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• F. Accessory sex glandsThese are several glands
  that add volume and nutrition to the sperm-rich
  fluid coming from the epididymis.
• G. Seminal vesiclesThe seminal vesicles open
  into the urethra.
• They produce a fluid that protects and transports
  the sperm.
• H. Prostate glandThe prostate gland is near the
  urethra and the bladder.
• It produces a fluid that is mixed with the
  seminal fluid.

15
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• I. Cowpers glandThe cowpers gland produces a
  fluid that moves down the urethra ahead of the
  seminal fluid.
• This fluid cleans and neutralizes the urethra,
  which helps protect the sperm as they move
  through the urethra.
• The mixture of the
  seminal and prostate
  fluid and the
  sperm
  is called semen.

16
What are the major reproductive organs in male
mammals? Whatare the functions of those organs?

• J. PenisThe penis deposits the semen within the
  female reproductive system.
• The urethra in the penis is surrounded by spongy
  tissue that fills with blood when the male is
  sexually aroused, which causes an erection that
  is necessary for copulation (mating) to occur.
• The sigmoid flexure (found in bulls, rams, and
  boars) and the retractor muscle extend the penis
  from the sheath, which is a tubular fold of skin.
  
• Horses and other mammals do not have a sigmoid
  flexure.

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18
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• Like males, female mammals have a complex system
  of organs that compose the reproductive system.
• It is important that those
  interested in animal
  production be familiar with
  these various organs and
  their functions.
• Some of the major organs that compose the female
  reproductive tract are

19
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• A. OvaryThe ovary produces female gametes, which
  are sex cells that can unite with other sex
  cells.
• These are called ova (eggs).
• A female mammal will typically have two ovaries,
  which also produce the female sex hormones
  estrogen and progesterone.
• Within each ovary, there are hundreds of tiny
  follicles or cavities.
• The ova are produced in the follicles.
• Each ovum is the largest single cell in the body.

20
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• B. OviductsThe oviducts are two tubes that carry
  the ova from the ovaries to the uterus.
• The oviducts are also called the fallopian tubes.
  
• The oviducts are close, but they are not attached
  to the ovaries.
• The funnel-shaped end of each oviduct that is
  close to the ovary is the infundibulum.
• At ovulation the follicle ruptures, releasing an
  ovum that is caught by the infundibulum.

21
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• After copulation, sperm move through the uterus
  to the oviduct.
• Fertilization of the ovum occurs in the upper end
  of the oviduct.
• The zygote, or
  fertilized egg cell,
  moves to the
  uterus about
  two
  to four days after
  fertilization.

22
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• C. UterusThe uterus of mammals is a Y-shaped
  structure consisting of the body, two uterine
  horns, and the
  cervix.
• The size and shape
  of the uterus varies
  among mammals.
• The upper part of the uterus consists of the two
  uterine horns that develop into the oviducts or
  fallopian tubes.

23
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• Mammals that normally produce large numbers of
  offspring at each breeding have relatively large
  horns and a small body.
• Those mammals that normally
  produce single offspring or
  twins have smaller horns and
  a larger
  body.
• In most mammals, pregnancy normally occurs in the
  uterine horns.
• In horses, however, pregnancy normally occurs in
  the body of the uterus.

24
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• In all mammals, the fetus grows within the
  uterus, where it remains until parturition or
  birth.
• The cervix is the lower outlet of the uterus and
  is composed primarily of connective tissue that
  constitutes the gateway between the uterus and
  the vagina.
• Like the rest of the reproductive tract, the
  cervix is lined with mucosal cells.
• These cells make significant changes as the
  animal goes from one estrous cycle to another and
  during gestation or pregnancy.

25
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• D. VaginaThe vagina serves as the female organ
  of copulation at mating and as the birth canal at
  parturition.
• It is the passage between the cervix and the
  vulva.
• The lining is moist during estrus and dry when
  the animal is not in estrus.

26
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• E. BladderThe bladder collects the liquid waste,
  which is called urine.
• The urine passes
  through the urethra to
  the vagina.
• The urethra attaches
  to the floor of the vagina
  between the cervix and
  the vulva.
• The bladder is not
  considered part of the reproductive tract
  in females.

27
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• F. VulvaThe vulva is the external opening of the
  reproductive and urinary systems.
• The exterior and visible
  part of the vulva consists
  of two folds called
  the labia
  majora.
• The labia minora are two
  folds located just inside
  the labia
  majora.

28
What are the major reproductive organs in female
mammals? What are the functions of those organs?

• G. ClitorisThe clitoris is the sensory and
  erectile organ of the female.
• It is located just inside the vulva.
• The clitoris develops from the same embryonic
  tissue as the penis in the male and produces
  sexual stimulation during copulation.

29
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• For an animal to effectively reproduce, the
  processes of spermatogenesis with males or
  oogenesis with females must be viable for an
  animals reproductive development.
• Spermatogenesis is the production of sperm and
  oogenesis is the production of egg cells.
• A. The process of spermatogenesis has many steps
  for effective sperm production.
• Spermatogonia, defined as primitive
  differentiated male gametes, are found along the
  outside wall of the seminiferous tubules.
• As these gametes increase in number due to
  mitosis, each increases in size and develops into
  a primary spermatocyte.

30
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• The process of spermatogenesis begins as the two
  secondary spermatocytes develop when each primary
  spermatocyte undergoes the first meiotic
  division.
• After this division is complete, the second
  meiotic division begins.
• Four spermatids develop after the second meiotic
  division.
• Each spermatid contains the haploid number of
  chromosomes.

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What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• For example, human sperm cells contain 23
  chromosomes, swine have 19 chromosomes, sheep
  have 27 chromosomes, cattle have 30 chromosomes,
  dogs have 39 chromosomes, cats have 19
  chromosomes, and chickens have 39 chromosomes.

33
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• As the spermatids develop into mature sperm, they
  lose a large amount of cytoplasm.
• The nucleus is condensed
  into a head, and a whip-
  like flagella tail
  is
  developed.
• There are three main
  structural characteristics of a mature sperm.
  
• For an animal to have viable sperm, each must
  have a head, body, and tail in its sperm
  structure.

34
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• B. Much like spermagenesis, oogenesis is
  necessary for female animals to reproduce.
• The steps of oogenesis are similar to
  spermagenesis in complexity, yet the steps differ
  in that only one sex cell is created, unlike the
  four sex cells created in spermagenesis.
• The first step of oogenesis begins when the early
  germ cells, called oogonia, grow into primary
  oocytes.
• The primary oocyte will divide into one polar
  body and one secondary oocyte.

35
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• The majority of the cytoplasm goes to the
  secondary oocyte, and the polar body is rather
  small.
• Each oocyte contains
  the same number of
  chromosomes.
• The secondary oocyte
  divides again, resulting
  in an ootid and another
  polar body.
• Sometimes in oogenesis, the first polar body will
  divide into two polar bodies.

36
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• Oogenesis results in one large ootid that
  contains the haploid number of chromosomes and
  most of the cytoplasm and three polar bodies.
• These polar bodies will disintegrate since they
  are nonfunctional.
• The large ootid then grows into a functioning
  ovum.
• The large size is needed to provide food for the
  embryo until it can receive nourishment from its
  mother.

37
What are the involved steps and processes of
spermatogenesis and oogenesis? What are the
characteristics of sperm and eggs?

• C. Both the spermatid and ootid possess either
  all maternal chromosomes, paternal chromosomes,
  or a combination of chromosomes from the mother
  and father.

38
What the major male and female reproductive
organs in poultry, and what are their functions?

• The reproductive systems of
  poultry are similar to those
  found in mammals, with a few
  differences.
• A. The reproductive system of male poultry
  includes the testicles, which are held within the
  body cavity rather than in a scrotum.
• The testicles produce the sperm and seminal
  fluid.
• 1. The vas deferens carries the seminal fluid and
  sperm cells to the cloaca.

39
What the major male and female reproductive
organs in poultry, and what are their functions?

• 2. The cloaca is the enlarged part where the
  large intestine joins the end of the alimentary
  canal.
• 3. The alimentary canal
  is the food-carrying
  passage that begins at
  the
  mouth and ends at
  the vent.
• 4. The papilla is the organ
  in the wall of the cloaca
  that puts the
  sperm cells into the hens reproductive tract.

40
What the major male and female reproductive
organs in poultry, and what are their functions?

• B. The reproductive system of female poultry
  includes two ovaries and two oviducts.
• The right ovary and
  oviduct do not function.
• Only the left ovary and
  oviduct produce eggs.
• The ova produced in
  the ovary develop into
  egg yolks.

41
What the major male and female reproductive
organs in poultry, and what are their functions?

• The oviduct of the chicken has five parts.
• 1. FunnelThe funnel receives the yolk from the
  ovary.
• The sperm cells that the chicken receives from
  the male are stored here.
• 2. MagnumThe magnum secretes the thick white of
  the egg.
• It takes approximately three hours for the thick
  white to be placed around the yolk in the magnum.

42
What the major male and female reproductive
organs in poultry, and what are their functions?

• 3. IsthmusThe yolk and thick white move from the
  magnum into the isthmus, where two shell
  membranes are placed around the yolk and thick
  white.
• This process takes
  approximately 1¼ hours.
• 4. UterusIn the uterus,
  the thin white and the outer
  shell are added to the egg.
• The egg remains in the uterus for approximately
  20 hours.

43
What the major male and female reproductive
organs in poultry, and what are their functions?

• 5. VaginaFrom the uterus, the egg moves into the
  vagina.
• The egg stays there
  only a short time, after
  which it is laid.
• It takes approximately
  25 to 27 hours for a
  chicken to
  produce one egg.

44
What are the methods used to castrate and neuter
animals?What are the benefits?

• The reproduction process can be eliminated in
  animals with various methods of neutering.
• There are two forms of animal neutering
  castration and spaying.
• Each form deals with the sex of the animal.
• With females, the neutering process is identified
  as spaying, and with males, it is called
  castration.

45
What are the methods used to castrate and neuter
animals?What are the benefits?

• Neutering is used often in the agriculture
  industry to remove an animals reproductive
  capability to prevent the passing of inferior
  genetics throughout a herd, to improve the meat
  quality of an animal, or to aid in the animals
  management.
• After being neutered, an animals
  sexual classification changes.
• For example, a bull calf is defined
  as a young male
  bovine.
• If the animal is castrated, it is
  classified as a steer, which is
  defined as a
  castrated male bovine.

46
What are the methods used to castrate and neuter
animals?What are the benefits?

• A. Castration is defined as the removal of an
  animals testicles.
• Frequently, these procedures are performed
  between three to four months of age to limit the
  development of the genitals, weight loss, and
  bleeding of the animal.
• The three most common types of castration are
  clamping, banding, and cutting.

47
What are the methods used to castrate and neuter
animals?What are the benefits?

• 1. Clamping involves using a pincer to sever the
  chord of each testicle.
• The process involves no
  blood and is considered a
  nonsurgical procedure.
• 2. Banding involves a special
  instrument that places a tight
  rubber band around the base of the
  scrotum.
• The band isolates the blood supply from the
  testicles, causing the testicles to wither from a
  lack of blood. This process involves no blood.
• 3. Cutting involves surgically removing the
  testes.

48
What are the methods used to castrate and neuter
animals?What are the benefits?

• B. Spaying deals with the removal of a female
  animals ovaries or cutting of the fallopian
  tubes so eggs cannot enter the uterus to be
  fertilized and develop into an embryo.

49
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• Reproduction is a series of events and phases
  that an animal experiences.
• Each event takes place in a certain order.
• The properly timed completion of these phases
  affects success.
• Some of the important phases in reproductive
  development are

50
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• A. PubertyPuberty is the time at which animals
  reach a level of sexual development that makes
  them capable of reproduction.
• Puberty in female animals is the age of the first
  estrus with ovulation.
• Puberty in males is the first
  ejaculate with fertile sperm.
• Neither males nor females
  are sexually mature at
  puberty.

51
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• The female is often too small to bear young.
• The male is not highly fertile and is not capable
  of breeding regularly.
• Environmental and genetic factors affect the age
  at which puberty occurs.

52
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• B. FertilizationFertilization is the union of a
  sperm and an ovum or egg.
• The sperm penetrates the ovum, and pairs of
  genetic material are formed.
• The fertilized ovum is called a zygote.
• C. GestationGestation is the period of
  pregnancy. It begins with conception and lasts
  until parturition (birth).
• The length of gestation varies between animals.

53
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• D. ParturitionParturition is the process of
  giving birth.
• Several hormone levels change and initiate the
  process.
• Behavior changes can be observed that indicate
  the animal is nearing parturition.
• For example, females can exhibit a nesting
  behavior.
• They become restless and attempt to separate from
  the herd.

54
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• The first stage of parturition includes dilation
  of the cervix and entry of the fetus into the
  cervix.
• This is usually the longest stage, ranging from
  one to 12 hours.
• The second stage involves strong contractions,
  leading to the birth of an animal.
• The last stage of parturition is the expulsion of
  the afterbirth (placenta) from the uterus, which
  normally occurs shortly after giving birth.

55
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?
56
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• E. LactationLactation is the production of milk.
  
• Hormones that trigger the onset of lactation also
  play an important role in parturition.
• F. IncubationIncubation is the development of a
  new animal in the fertile egg of poultry, fish,
  and other egg-laying species.
• This occurs outside the body of the female.

57
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• Four important factors in incubating eggs are
• 1. TemperatureThe temperature should be
  maintained at 99 to 103F (37.2 to 39.4C).
• 2. HumidityThe humidity should be approximately
  60 percent during the first 18 days and 70
  percent during the last three days.
• 3. OxygenSufficient air exchange is necessary to
  prevent carbon dioxide buildup while maintaining
  a 21 percent oxygen level.

58
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• 4. Egg rotationEggs should be rotated two to
  five times daily for the first 18 days.

59
What are the phases of reproductive development
in the life of an animal? How do you determine
animal readiness for breeding?

• K. SpawningSpawning is the releasing of eggs by
  a female fish and the subsequent fertilization by
  the male.
• A female may lay thousands of eggs at one
  spawning.
• The male fish then fertilizes the eggs by
  releasing sperm on the mass of eggs.

60
Review

• What are the major reproductive organs in male
  mammals? What are the functions of those organs?
• What are the major reproductive organs in female
  mammals? What are the functions of those organs?
• What are the involved steps and processes of
  spermatogenesis and oogenesis? What are the
  characteristics of sperm and eggs?

61
Review

• What the major male and female reproductive
  organs in poultry, and what are their functions?
• What are the methods used to castrate and neuter
  animals? What are the benefits?
• What are the phases of reproductive development
  in the life of an animal? How do you determine
  animal readiness for breeding?

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