Reproductory System Male reproductive system Male Anatomy • Male reproductive is made up of a pair of testicles, vas deferens, urethra and penis with its associated organs. Location of the male organs (bull) Scrotum The external sac that holds testicles outside of the body. • The scrotal skin is thin, pliable and relatively hairless. • Tunica Dartos-A layer of fibro-elastic tissue mixed with smooth muscle fibres that lies immediately below the skin of scrotum. It contracts in cold exposure to keep the testis close to the body. • Scrotal septum-Divides the scrotum into two compartments for each testis. • The testes descends into the scrotum in the embroyonic stage or later after birth. • Except in elephant and rooster. • Spermatic cord- It suspends testes within the scrotum. Contains blood vessels,nerves, lymphatics and ductus deference. • keep sperm at 4-5oF cooler than the body temperature for effective sperm production Testes The primary male organs of reproduction (testis is singular; testes is plural) • Vary in shape,size and location between species. • In horses- nearly horizontal and close to the abdominal wall. • In bulls and small ruminants-nearly vertical and pendulous. • In pigs-just ventral to the anus (perineal) Functions of the testicles: 1. To produce spermatozoa in the seminiferous tubules. 2. To secrete testosterone ; -male sex hormone that stimulates the development of the male sex characteristics. Semeniferous tubules Semineferous tubule • Mass of coiled tubule within the interstitial tissue. • Site of spermatogenesis • Many s. tubules deliver sperm into a netwrok of larger tubules known as rete testis. • Rete testis drains into efferent ductules that connect to the epididymis head. • The interstitial tissues between the s. tubules contains leydig cells that produces testosterone. The epithelium of s. tubules contains: 1. Sertoli cells/sustentaculer cells- nourishes the developing sperm cells. 2. Germ cells-precursors for spermatozoa. Epididymis Head Body Tail • Composed of a long, convoluted tube. • Connects efferent ductules with the ductus deferens • The common path sperm take after formation in the seminiferous tubules; sperm mature and accumulate here prior to ejaculation. • Divided into head, body and tail. Functions of the epididymis: 1. Provide passageway for sperm out of the seminiferous tubules. 2. Storage for sperm. 3. Fluid secretion to nourish sperm . 4. Place for sperm maturation . Ductus deferens • Tube connecting epididymis to urethra. • Muscular tissue - undergoes peristaltic contraction during ejaculation propelling the spermatazoa from epididymis to urethra. Urethra • long tube from bladder to penis • passageway for urine and sperm out of the body AAP/reproductivesystem/pj-03 17 Accessory sex glands • Produce the bulk of the semen. • Nutrition for spermatazoa • Buffer against the natural acidity of the female genital tract. A. Ampullae: • Glandular enlargements at the terminal end of the ductus deferens. • Absent in boars. • Secretion contributes to the volume of the semen. B. Seminal vesicles : • lobed organ near the end of the vas deferens • add fructose and citric acid to nourish the sperm C. Prostate Gland located at the neck of the bladder. • Cleans the urethra prior to and during ejaculation. • Provides minerals for spermatozoa. • Provides the medium for sperm transport. • Provides the characteristic odor of semen. D. Bulbourethral (Cowpers) gland • paired organs at neck of bladder. • To clean the urethra prior to semen passage. Penis • The male organ of copulation • Divided into: 1. Glans penis-free extremity. 2. Body- the main shaft. 3. Two crura-the roots. • The bulk of penile body is composed of erectile tissue-corpora cavernosa. • Corpora cavernosa contains blood sinusoids divided by connective tissue known as trabeculae. • Filling up of these sinusoids with blood-erection • Two types of penis 1. Fibroelastic –in ruminants and swine. • Trabeculae form the bulk of the penis. • Firm even when penis is not erect. 2. Musculocavernous penis-in horse, human. • Blood sinusoids forms the bulk of the penis. • Flaccid when not erect. Prepuce • Invaginated fold of skin sorrounding the free extremity of the penis. Clinical importance • Phimosis- inability of penis to protrude out of prepuce. • Paraphimosis-inability of penis to retract into the prepuce after protrusion. • Penile fracture seen in dogs because of presence of bone in penis-Os penis. • Scrotal hernia-migration of internal organs into scrotum. • Brucellosis-bacterial disease affecting testicles. • Cryptochid-A condition where the testis fails to descend into the scrotum. If both the testis are retained most likely the animal will be sterile. • Castration-removal of testes in male animal. However technically also for ovariectomy. FEMALE REPRODUCTIVE SYSTEM • Female reproductive system is made up of a pair of ovary, oviduct, uterus, cervix, vagina and vulva. Location of female reproductive organs Ovaries • Comparable to the male testes. • Primary organs of reproduction in female. • Found at the lumbar region of the abdominal cavity. • All species contain two functional ovaries except for the hen, which has only a left functioning ovary. • Site of gamete production (bovine animal has 20,000 potential eggs per ovary. • Ova are fully developed at puberty and are not continuously produced as in the male. The ovaries have three major functions: • To produce gametes. • Secrete estrogen. Estrogen is the hormone responsible for the secondary sex characteristics in the female: – Absence of muscle development – Development of mammary glands – Development of reproductive systems and external genitalia – Fat deposition on hips and stomach (source of energy) – Triggering of estrous cycle at puberty – Triggering of heat Corpus leutum (remnant after ovulation) • That releases progesterone, which is required for the maintenance of pregnancy if animal get pregnant. Infundibulum • the flared portion of the fallopian tube near the ovary that catches the ovulated egg. • Cilia movement and muscle contractions push the ovum into the fallopian tube. Fallopian Tubes (Oviducts) – • pair of small cilliated tubes leading from the ovaries to the horns of the uterus. • Fertilization occurs in the upper 1/3 of the oviduct. • The lining is much folded and its cells becomes actively secretory during heat. • Made up of connective tissue submucosa and muscular layer of smooth muscles. • Cilia and smooth muscles helps in movement of spermatozoa and ova. Uterus • The muscular sac connecting the fallopian tubes to the cervix. • Suspended from the body wall by broad ligament. • Broad ligaments are made up of-mesometrium, mesosalpinx and mesovarium. • Consists of body and horns. • Uterine Horn - the anterior, divided end of the uterus in cow, ewe, and mare. Sow has only 2 horns, no body; woman has no horns, only body. Uterine wall consists of: • Endometrium-mucosa lining of the uterus. Higly glandular tissue. Its thickness changes with estrus cycle and pregnancy. • Myometrium- muscular portion of the uterine wall. Consists of thick inner circular layer of smooth muscles and a thinner outer longitudinal layer of smooth muscles seperated by a vascular layer. The uterus has three major functions: • Sustains the sperm and aids in its transport to oviduct . • Supports embryo and fetus during gestation. • Expels fetus at parturition. Cervix • A heavy smooth muscle sphincter that is tightly closed located between the uterus and vagina. • Projects caudally into the vagina. • Cervix slightly relaxes during estrus and parturition. Vagina • The female organ of copulation. • Portion of reproductive tract between the uterus cranially and vulva caudally. Functions of the vagina: • Admits penis. • Receives semen. • Passageway for fetus at parturition. Vulva • External genitalia of the female. • Consists of left and right labia. • The labia meets at the dorsal and ventral commissures. Clitoris • Small pea-like enlargement at the ventral commissure. • Often concealed by labia. • Equivalent to penis in males. • Just like penis, it is composed of two crura, body and glans. • Only glans is visible and contains sensory nerve endings. Bladder - storage organ for urine. Urethra - opening of bladder into vagina. Ovulation Rates by Species cow • 1 egg per estrus ewe • 1 - 3 eggs per estrus sow • 10 - 20 eggs per estrus mare • 1 egg per estrus hen • ~ 28 eggs per month • At ovulation, the ruptured follicle, or corpus luteum, becomes a temporary endocrine organ, secreting progesterone • The infundibulum pushes the ovum into the fallopian tube If not, an ectopic pregnancy may occur. The egg is fertilized in the upper 1/3 of the oviduct and then moves to the uterus. Develop embryo in uterus from fertilization to parturition (this period is gestation) Expel fully developed young at birth (parturition) Clinical terms/importance Dystocia- Difficult birth. Process where normal delivery is not possible and requires intervention from external. Prolapse: Protrusion of organ out of natural opening. Example: Vaginal, uterine, anal prolapse. Retention of placenta: The plancenta is not expelled out after the birth. This can cause infection, metritis, toxaemia and death. • Under developed genital tract due to poor nutrition may result in late onset of estrus • Freemartin- Condition where the female twin is sterile when the other twin is male. This happens due to fusion of blood supply between the two twins during development. The hormones from the male fetus dominates/suppreses the normal development of female reproductive parts in the felmale twin. The female twin is therefore sterile. This is more common in cattle and rare in pigs, horses and goats.