1.
Reproductive System
VTT 235/245

2.
MALE ANATOMY

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.

5.
Structures
 The Spermatic Cord consists of-
 Vas deferens
 Testicular artery, vein, nerve, and
lymphatics

6.
Accessory Sex Glands
 Prostate
 Seminal vesicles
 Bulbourethral glands

7.
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.

8.
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

9.
MALE PHYSIOLOGY

10.
Testosterone
 Produced by the testes.
 Responsible for secondary sex
characteristics and sex drive.
 An androgen or anabolic steroid.
 Production is stimulated by LH.

11.
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.

12.
Seminal Fluid
 Produced by accessory sex organs.
 The medium for survival of the
sperm.
 Prostatic secretion- alkalinizes the
vaginal environment to prevent sperm
death.

13.
MALE PATHOLOGY

14.
Prostatic Disease
 Common in dogs
 Benign Prostatic Hyperplasia
 Prostatic adenocarcinoma
 Bacterial
 All cause enlargement or
inflammation

15.
Orchitis & Epididymitis
 Acute-
 Caused by trauma, infection, or
testicular torsion
 Chronic-
 Immune-mediated or neoplastic
 Testicular atrophy and fibrosis

16.
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

17.
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!!!

18.
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.

19.
FEMALE ANATOMY
Structures

20.
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.

21.
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.

22.
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.

23.
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.

24.
Uterus
 Uterine Walls- 3 layers

25.
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.

26.
Other Structures…
 Vulva- the external orifice that
terminates the genital tract.
 Labia- the Ⓡ and Ⓛ lips of the vulva.

27.
FEMALE PHYSIOLOGY

28.
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.

29.
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.

30.
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).

31.
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.

32.
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.

33.
Stages of the Estrous Cycle

34.
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.

35.
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.

36.
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.

37.
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.

38.
4. Anestrus
 Periods of no estrous cycles
 a. Pregnancy
 b. Nursing
 c. Season of year
 d. Poor Nutrition
 e. Pathological Conditions

39.
PREGNANCY

40.
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

41.
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.

42.
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.

43.
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.

44.
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.

45.
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.

46.
FEMALE PATHOLOGY

47.
Uterine Infection
 Infection of the uterus.
 Endometritis- inflammation of the
endometrium.
 Metritis- inflammation of all layers.
 Pyometra- accumulation of pus in the
uterus.

48.
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.

49.
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.

50.
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

51.
LABORATORY ANALYSIS
VAGINAL CYTOLOGY
Hendrix p. 327

52.
Anestrus
 Predominantly
non-cornified
squamous
epithelial cells
 Lg nucleus
and rounded
edges

53.
Proestrus
 Above- early
proestrus, below-
late proestrus
 Cornified
squamous
epithelial cells
 Angular with
jagged borders
 Segs(neutraphils)
decrease, RBC’s
increase

54.
Estrus
 All squamous cells
are cornified
 Segs- absent,
RBC’s present

55.
Diestrus
 Non-cornified
squamous and
abundant cytologic
debris
 Segs increase,
RBC’s are absent
 Similar to anestrus

56.
LABORATORY ANALYSIS
SEMEN ANALYSIS

57.
Semen Collection

58.
Semen Analysis
 Sample Handling-
 Avoid exposure to marked changes in
temperature
 Supplies-
 Slides, coverslips, pipettes, stains and
diluents

59.
Semen Analysis
 Evaluation-  Morphology-
 Volume  Head
 Appearance  Midpiece
 Motility  Tail
 Concentration
 Live:Dead Ratio

60.
Primary Abnormalities

61.
Primary Abnormalities

62.
Secondary Abnormalities

63.
Semen Analysis

64.
The End!!