Male Reproductive System
· The male reproductive organs include a pair of testes, a pair of the epididymis, a pair of vasa deferentia, urethra, penis and some accessory glands.A. Testes
· The paired testes are small, ovoid bodies of light pink colour.
· The paired testes are small, ovoid bodies of light pink colour.
· Each testis lies in scrotum which is located outside the abdominal cavity, ventrally in the pubic region. So-called extra-abdominal testis.
· In the foetus and newly born rabbit, the testes lie within the abdominal cavity near the kidneys where they were developed. But at puberty, they descend through inguinal canals into scrotal sacs.
· The outer protective covering of testis is called tunica albuginea, formed by white fibrous connective tissue, which projects the testis.
· In most species of mammals, the testes remain within scrotal sacs throughout life.
· In the foetus and newly born rabbit, the testes lie within the abdominal cavity near the kidneys where they were developed. But at puberty, they descend through inguinal canals into scrotal sacs.
· The outer protective covering of testis is called tunica albuginea, formed by white fibrous connective tissue, which projects the testis.
· In most species of mammals, the testes remain within scrotal sacs throughout life.
· But in rabbits, rats and other rodents, they are migratory.
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| Male reproductive system of Rabbit & L.S. of testis and epididymis showing structure and relationship. |
· They descend into the scrotum during the breeding season but withdraw into the abdominal cavity during non-breeding periods through inguinal canals which remain open throughout life.
· Histologically, the mammalian testis is composed of a number of cone-shaped compartments or lobules which are separated by interlobular septa.
· Each lobule contains long, slender, much convoluted microscopic seminiferous tubules bound together by connective tissue.
· The germinal epithelium lining of the seminiferous tubules is made of two kinds of cells:
A) Spermatogenic cells – It is found in numerous, the smaller which undergoes spermatogenesis to produce spermatozoa.
B) Sertoli cells – It is few in number, larger, tall, columnar supporting cells which nourish the developing sperms before they leave the tubule.
· Each sperm consists of a head composed mainly of the nucleus, and a long cytoplasmic tail.
· Interstitial cells or the cells of Leydig are scattered in the connective tissue between the seminiferous tubules which secrete testosterone hormone to produce secondary sexual characters.
· All the seminiferous tubules in each testis is opened into a network called rete testis. It opens by fine ductules lined by cilia, called vasa efferentia into the epididymis.
· The spermatozoa produced by testis are transferred through vasa efferentia into the epididymis.
B. Epididymis
· The epididymis is an irregular, narrow and highly convoluted tubule with great length.
· It forms a compact ridge-like along the inner surface of the testis.
· The epididymis has three distinct parts:
a) Caput epididymis or globus major:
· It is the head anterior part that is connected with the anterior end of the testis through vasa efferentia.
a) Caput epididymis or globus major:
· It is the head anterior part that is connected with the anterior end of the testis through vasa efferentia.
· It lies buried in the fat body.
· It is also connected with the abdominal wall by a spermatic cord consisting of connective tissue, spermatic artery, spermatic and a nerve.
· While posterior part of the testes is connected by elastic fibre with scrotal sac called gubernaculum.
· The vein forms an extensive network around the artery called the pampiniform plexus.
· The vein forms an extensive network around the artery called the pampiniform plexus.
b) Corpus epididymis:
· It is the body or middle part connecting the caput and cauda epididymis.
· The two epididymis serve to store and nourish the spermatozoa.
c) Cauda epididymis or globus minor:
· It is the tail posterior part that connects the posterior end testis to the scrotal sac by a thick elastic co connective tissue, called the gubernaculum.
· It is the tail posterior part that connects the posterior end testis to the scrotal sac by a thick elastic co connective tissue, called the gubernaculum.
· When it shortens, it draws the testis into the scrotal sac.
C. Vasa deferentia
· The cauda epididymis leads into a yellow, white, straight, muscular tube, the sperm duct or vas deferens.
· The cauda epididymis leads into a yellow, white, straight, muscular tube, the sperm duct or vas deferens.
· It runs forwards along the inner side of the scrotal sac, traverses the inguinal canal to enter the abdominal cavity, loops ventrally under the ureter and opens dorsally into the urethra immediately in front of the opening of the ureter.
· A small, slightly bifurcated blind sac the uterus masculinus or seminal vesicle, opens dorsally into the urethra just dorsal to the openings of vasa deferentia.
· A small, slightly bifurcated blind sac the uterus masculinus or seminal vesicle, opens dorsally into the urethra just dorsal to the openings of vasa deferentia.
D. Urethra
· The neck of the urinary bladder and the vasa deferentia open into a thick-walled muscular duct called the urethra.
· It is the common passage for both urine and semen and called the urinogenital duct which traverses and opens at the tip of the penis as the male urinogenital aperture.
· The neck of the urinary bladder and the vasa deferentia open into a thick-walled muscular duct called the urethra.
· It is the common passage for both urine and semen and called the urinogenital duct which traverses and opens at the tip of the penis as the male urinogenital aperture.
E. Penis
· The copulatory organ or penis is a small, cylindrical and erectile organ that serves to transmit sperms into the vagina of the female during sexual intercourse.
· It is composed of three longitudinal columns of spongy erectile tissues two corpora cavernosa and the corpus spongiosum.
· These tissues become filled with blood during sexual excitement to produce an erection of the penis.
· The copulatory organ or penis is a small, cylindrical and erectile organ that serves to transmit sperms into the vagina of the female during sexual intercourse.
· It is composed of three longitudinal columns of spongy erectile tissues two corpora cavernosa and the corpus spongiosum.
· These tissues become filled with blood during sexual excitement to produce an erection of the penis.
· The penis is enclosed in a sheath of skin which hangs loosely as a fold-over its cap-like tip or glans penis as prepuce.
· The operation of circumcision is the removal of the prepuce.
· The operation of circumcision is the removal of the prepuce.
F. Accessory Sex glands:
· Several accessory glands open into the urethra of males.
· Several accessory glands open into the urethra of males.
· Their secretions, together with those of epididymis and masculinus, constitute the seminal fluid or semen.
a. Prostate gland
· A large prostate gland lies dorsally around the base of the uterus masculinus.
· A large prostate gland lies dorsally around the base of the uterus masculinus.
· It opens into the urethra by several small ducts. Its whitish alkaline secretion activates the passive spermatozoa.
b. Cowper’s glands
· A pair of bulbourethral or Cowper’s glands lie posteriorly to the prostate dorsally at the base of the penis.
· Their secretion neutralizes acidity for the protection of spermatozoa.
· A pair of bulbourethral or Cowper’s glands lie posteriorly to the prostate dorsally at the base of the penis.
· Their secretion neutralizes acidity for the protection of spermatozoa.
c. Perineal glands
· These are a pair of dark elongated scent glands lying behind the Cowper’s glands.
· These are a pair of dark elongated scent glands lying behind the Cowper’s glands.
· They open into the hairless perineal depressions one on either side of the anus.
· Their odorous secretion gives the rabbit its characteristic smell.
d. Rectal glands
· A pair of rectal glands are situated dorsally on the rectum.
· Its secretion encourages the rabbit to copulate.
· A pair of rectal glands are situated dorsally on the rectum.
· Its secretion encourages the rabbit to copulate.
Female Reproductive System
· The female reproductive organs include a pair of ovaries, a pair of oviducts, a pair of uteri, vagina, vestibule, clitoris and some accessory glands.A. Ovaries
· The two ovaries are small, whitish, oval bodies, about 2 cm long.
· The two ovaries are small, whitish, oval bodies, about 2 cm long.
· Each ovary is attached to the dorsal abdominal wall by a double fold of peritoneum called mesovarium behind each kidney.
· Surface of ovaries contains many small, rounded, semitransparent projections called Ovarian or Graafian follicles, each containing a developing ovum.
· Surface of ovaries contains many small, rounded, semitransparent projections called Ovarian or Graafian follicles, each containing a developing ovum.
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| Rabbit. L.S. of Ovary |
· Histologically, the ovary has a peripheral layer of germinal epithelial cells surrounding a dense mass of connective tissue fibres, called stroma which contains blood and lymph vessels and nerves.
· The stroma contains groups of actively dividing germinal cells, called follicles.
· In each follicle, a single cell, destined to become an oocyte or ovum, enlarges while other cells surround and form a protective mass called discus proligerus which is attached to one side of the follicle.
· In each follicle, a single cell, destined to become an oocyte or ovum, enlarges while other cells surround and form a protective mass called discus proligerus which is attached to one side of the follicle.
· When ripe, the follicles are known as Graafian.
· Each follicle contains a large fluid-filled follicular cavity.
· The cells lining the follicular cavity are membrana granulosa.
· The cells lining the follicular cavity are membrana granulosa.
· The fully mature surrounded by a thick transparent membrane zona pellucida containing yolk and fat is covered by another striated layer of cells, called corona radiata.
· In the stroma, groups of interstitial cells are present which secrete sex hormones (oestrogen).
· Finally each mature follicle bursts to release the oocyte into a body cavity, a process known as ovulation.
· The follicular cells remaining divide rapidly to form yellowish solid cells called corpus luteum.
· In the stroma, groups of interstitial cells are present which secrete sex hormones (oestrogen).
· Finally each mature follicle bursts to release the oocyte into a body cavity, a process known as ovulation.
· The follicular cells remaining divide rapidly to form yellowish solid cells called corpus luteum.
· It also serves as a temporary endocrine gland because it secretes hormone (progesterone) which causes the uterus to enlarge to receive the growing foetus and stimulates lactation.
· If the ovum is not fertilized, the corpus luteum gradually disappears leaving a scar called Corpus Albicans.
· If the ovum is not fertilized, the corpus luteum gradually disappears leaving a scar called Corpus Albicans.
B. Oviducts
· It is a long and coiled tube that is divisible into two parts:
1. Fallopian or oviducal funnel
· Each oviduct opens anteriorly close to the outer border of the ovary of its side by a wide funnel called the oviducal funnel.
· Opening of funnel is ostium, which is ciliated to receive ovum released from the ovary.
2. Fallopian tube
· It is a short, narrow, coiled internally ciliated duct. It conducts ovum by ciliary action and provides the platform for fertilization.
· It is a short, narrow, coiled internally ciliated duct. It conducts ovum by ciliary action and provides the platform for fertilization.
3. Uterus
· The fallopian tube is followed by a much wider, vascular, longer convoluted, thick-walled tube the uterus. It is highly distensible and attached to the abdominal wall by a mesentery.
· It provides the platform for the implantation of fertilized ova zygotes to develop into embryos or foetuses, each attached to the placenta by an umbilical cord.
· The fallopian tube is followed by a much wider, vascular, longer convoluted, thick-walled tube the uterus. It is highly distensible and attached to the abdominal wall by a mesentery.
· It provides the platform for the implantation of fertilized ova zygotes to develop into embryos or foetuses, each attached to the placenta by an umbilical cord.
4. Vagina and Vestibule
· It is formed by the union of two uteri as a long wide, median duct which lies dorsally upon the urinary bladder.
· It opens posteriorly into the neck of the bladder to join the urethra forming a short narrow common urinogenital canal or vestibule.
· It is formed by the union of two uteri as a long wide, median duct which lies dorsally upon the urinary bladder.
· It opens posteriorly into the neck of the bladder to join the urethra forming a short narrow common urinogenital canal or vestibule.
· It runs backwards ventral to the rectum and opens to the exterior by a slit-like aperture, the vulva.
· The vagina serves to receive the penis of the male during copulation.
· The vagina serves to receive the penis of the male during copulation.
5. Clitoris
· It develops from the anterior wall of the vulva as a small erectile organ of the female.
· It develops from the anterior wall of the vulva as a small erectile organ of the female.
· It is homologous with the male penis.
6. Accessory Sex Glands
· In the female, there is no prostate gland.
· In the female, there is no prostate gland.
· A pair of small Bartholin's glands or Cowper's glands lie embedded in the wall of the vestibule.
· Their viscid secretion lubricates the vaginal passage.
· Their viscid secretion lubricates the vaginal passage.
· They are reduced in size or absent.
· The perineal and rectal glands are similar to the male.
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