This document provides an overview of the male and female reproductive systems in animals. For the male anatomy, it describes the testes, scrotum, seminal vesicles, prostate, penis and other structures. It also discusses sperm production, testosterone production and common male pathologies. For the female, it outlines the ovaries, oviducts, uterus, cervix, vagina and vulva. It explains the estrous cycle, hormones, pregnancy, parturition and common female reproductive issues. It concludes with descriptions of vaginal cytology and semen analysis for laboratory evaluation.
3. Structures
Testes-
Male gonad that produces both testosterone
and germ cells (which become sperm).
Contained in the scrotum.
Scrotum- pouch containing the testicles
and epididymis.
Seminiferous Tubules-
Hollow structures where germ cells
differentiate into spermatozoa.
4. Structures
Epididymis-
Structure adjacent to the testicle.
3 parts: head, body, and tail.
Spermatozoa mature in the head and body of
the epididymis.
Ductus Deferens (Vas Deferens)-
The continuation of the epididymal duct at
the tail of the epididymis.
It travels up the spermatic cord and through
the inguinal canal to reach the abdomen.
6. Structures
The Spermatic Cord consists of-
Vas deferens
Testicular artery, vein, nerve, and
lymphatics
8. Penis
The male copulatory organ.
Provides a passage way for semen
and urine to the outside of the body.
Prepuce- the cutaneous sheath
around the free part of the penis
when it is not erect.
Preputial Orifice- the external
opening of the prepuce to the
outside environment.
9. Penis
Contains the glans penis (head of the
penis)
Bulbus Glandis- the caudal part of
the penis.
Swells to lock the male into the female
during copulation.
+/- Os penis
11. Testosterone
Produced by the testes.
Responsible for secondary sex
characteristics and sex drive.
An androgen or anabolic steroid.
Production is stimulated by LH.
12. Sperm
Spermatogenesis is stimulated by FSH.
Head-
Contains the nucleus and haploid chromosomes.
Acrosome- a cap which contains enzymes to
permit penetration into the ovum.
Midpiece-
Power plant
Numerous mitochondria carry-out metabolism
that provides ATP for sperm locomotion.
Tail- consists of flagellum for propulsion.
13. Seminal Fluid
Produced by accessory sex organs.
The medium for survival of the
sperm.
Prostatic secretion- alkalinizes the
vaginal environment to prevent sperm
death.
15. Prostatic Disease
Common in dogs
Benign Prostatic Hyperplasia
Prostatic adenocarcinoma
Bacterial
All cause enlargement or
inflammation
16. Orchitis & Epididymitis
Acute-
Caused by trauma, infection, or
testicular torsion
Chronic-
Immune-mediated or neoplastic
Testicular atrophy and fibrosis
17. Phimosis
The inability to extrude the penis
through an abnormally small preputial
orifice
Congenital or it develops due to
inflammation, neoplasia, edema, or
fibrosis after trauma, irritation or
infection
18. Paraphimosis
The inability to completely retract
the penis
Usually occurs after an erection
The preputial orifice skin becomes
inverted and impairs venous drainage
A medical emergency!!!
19. Pathologies
Inguinal Hernia-
The protrusion of a loop of organ or
tissue through the inguinal canal.
Cryptorchidism-
Failure of one or both testicles to
descend into the scrotum.
The retained testicle can be anywhere
between the scrotum and the caudal
pole of the kidney.
21. Structures
Ovaries
Oviducts (uterine tubes)
Uterus- horns and body
Cervix- a heavy, smooth muscle sphincter
that is kept tightly closed except during
estrus and parturition.
Vagina- glandless mucosa located within
the pelvic canal.
Vulva- consists of the vestibule and labia.
23. Ovaries
Ovaries- both endocrine (hormone
producing) and cytogenic (cell
producing).
Medulla- vascular center of the ovary.
Cortex- where follicles can be found,
both developing and atrophying.
Functions-
To produce ova or eggs ready for
fertilization.
Acts as an endocrine gland.
24. Oviducts
Oviduct- the open end of the uterine
tube (fallopian tube)
Functions-
Collects ova as they are released.
Conveys ova from the ovaries to the
uterine horns.
Infundibulum- funnel-shaped ovarian
end of the oviduct.
26. Uterus
Highly expandable, tubular organ
where the embryo/fetus develops.
A hollow structure with 3 parts-
neck (where the cervix is located),
body, and horns.
Function-
Provides a receptacle for embryos to
develop.
Provides nutrients via the PLACENTA.
28. Vagina
The part of the reproductive tract
between the cervix and the vulva.
Along with the vestibule and vulva, it
is the females copulatory organ and
birth canal.
The hymen is the poorly developed,
vestigial, mucosal folds at the
junction of the vagina and vestibule.
29. Other Structures
Vulva- the external orifice that
terminates the genital tract.
Labia- the and lips of the vulva.
31. Types
Monestrous- usually one cycle per year,
usually seasonal breeders. (mink)
Polyestrous- more than one cycle per year,
continuous. (swine)
Seasonally Polyestrous- cycles
continuously in specific seasons.
Induced Ovulators- requires copulation to
ovulate.
Spontaneous Ovulators- ovulation occurs
naturally, with or without copulation.
32. Estrous Cycle
The onset of the estrous cycle begins at
puberty.
The purpose is to prepare the uterus to
receive fertilized ovum.
Sexual maturity brings about-
ovarian development, which includes the
production of ova,
ovulation,
and the production of the corpus luteum.
The estrous cycle is under the control of
hormones produced by the ovaries and the
pituitary gland.
Animals do not undergo menopause.
33. Estrous Cycle
At the beginning of each cycle, ova within
the follicles in the ovaries begin to
develop.
One or more follicles (depending on the
species) continue to develop until they
reach a ripened follicle
One or more follicles rupture, (ovulation,
usually occurs during estrus.)
Then the ovum is expelled from the ovary
to the oviduct (uterine tube).
34. Estrous Cycle
The ruptured follicle grows larger, filling
with a yellow, lipoid material and becomes
the CORPUS LUTEUM (yellow body).
The corpus luteum secretes progesterone.
If fertilization occurs, the corpus luteum
continues to secrete progesterone and
prevents future estrous cycles during
pregnancy.
35. Estrous Cycle
Without fertilization, the corpus
luteum and its secretions diminish,
forming a CORPUS ALBICANS
(white body).
The reduced levels of hormone
production lead to a new estrous
cycle.
37. 1. Proestrus
Period of preparation.
**FSH & LH cause the development
of the follicle.
The follicle starts producing
ESTROGEN.
Estrogen stimulates the vagina and
uterus for copulation and pregnancy.
38. 2. Estrus
Period of female sexual receptivity.
Uterus and uterine horns are ready
to receive an embryo.
Release of LH causes ovulation.
Dogs may have bloody discharge, cats
may exhibit behavioral changes.
39. 3. Diestrus & Metestrus
Post-ovulating phase.
Each ruptured follicle develops into a
corpus luteum (CL).
The CL starts to secrete
PROGESTERONE which inhibits the
development of new follicles.
The CL is also responsible for
maintaining the uterine lining to
support the fetus during pregnancy.
40. 3. Diestrus & Metestrus
If pregnancy does not occur, the CL
degenerates.
If pregnancy occurs, the corpus luteum is
maintained and continues to secrete
hormones for:
The entire pregnancy or,
Until the placenta develops.
Depends on the species.
41. 4. Anestrus
Periods of no estrous cycles
a. Pregnancy
b. Nursing
c. Season of year
d. Poor Nutrition
e. Pathological Conditions
43. Gestation Periods
**Dog- Pig-
57-63 days 114 days
**Cat- Sheep & Goats-
65 days 150 days
Horse- Mice-
330 days 19-21 days
Cow- Rats-
283 days 21-23 days
Rabbits- Hamsters-
30-33 days 15-18 days
Guinea pigs- Gerbils-
59-72 days 23-26 days
44. Terms
Gestation- the interval between
fertilization of the ovum and the birth of
the offspring.
Mitosis- cell division, one cell divides into
2, 2 into 4
Zygote- fertilized ovum
Embryo- stage at which major organs are
developing.
Fetus- stage where formation of major
internal and external structures is
complete until the time of parturition.
45. Fertilization & Cell Division
Ova enter the infundibulum and are
transported down by muscular
contractions.
Sperm travels up the female tract and
fertilization takes place in the upper part
of the uterine tube.
Each ovum is penetrated by one sperm
which results in a fertilization reaction
(preventing fertilization by any other
sperm).
The fertilized ovum is now a zygote, and
cell division begins via mitosis.
46. The Placenta
A membranous structure that obtains
nutrients and oxygen from the mother to
deliver to the fetus.
Attaches to the endometrial lining of the
uterus.
Chorion- outer layer in contact with the
maternal uterus.
Amnion- innermost membrane closest to the
fetus.
Amnionic Sac- sac in which the fetus is
located.
47. Hormones
Oxytocin-
**Produced by the Posterior pituitary
Stimulates milk let-down.
In the presence of Estrogen, it
stimulates uterine contractions during
parturition.
Stimulates the oviducts to help move
spermatozoa.
48. Hormones
Prolactin-
**From the Anterior pituitary
Helps maintain the CL during pregnancy.
Stimulates the mammary glands to fill
with milk at parturition.
Stimulates the replenishment of milk via
neonatal suckling.
50. Uterine Infection
Infection of the uterus.
Endometritis- inflammation of the
endometrium.
Metritis- inflammation of all layers.
Pyometra- accumulation of pus in the
uterus.
51. Pyometra
A hormonally mediated disorder.
An abnormal uterine endometrium
combined with a secondary bacterial
infection.
Often occurs when progestational
compounds are administered to delay
or suppress estrus.
52. Uterine Prolapse
The turning inside-out of the uterus
and vagina causing it to project
through the vulva.
Most common in the cow and sow.
The prolapsed uterus can often be
pushed back in and sutured in place
until it heals.
53. Pseudocyesis
False pregnancy
Common in dogs
Occurs at the end of diestrus,
characterized by hyperplasia of the
mammary glands, lactation, and
behavioral changes
Falling progesterone and increasing
prolactin are believed to be the
cause