Male Reproductive System PDF 2024-2025

Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th...

Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 MALE REPRODUCTIVE SYSTEM Embryological; the reproductive system is closely related to the urinary system, often both are considered together under the title "Urogenital System". The male reproductive system consists of: 1. Two testes (testicles) – are essential organs. 2. Duct system [epididymis and ductus deferens (vas deferens)]. 3. Accessory sex glands. 4. Male urethra and penis. The testes produce spermatozoa (the male sex cells also called sperm) and testosterone (the male sex hormone). The remaining structures assist the spermatozoa to reach their ultimate goal (the ovum of the female) in a conducive to fertilization of the ovum; these structures include the epididymis and ductus deferens for each testis, accessory sex glands [ampulla, seminal vesicles, prostate, and bulbourethral (Cowper's) glands], urethra and penis. 1 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 Figure 1 Reproductive organs of bull Scrotum The scrotum is a coetaneous (skin) sac; a layer of fibro-elastic tissue mixed with smooth muscle fibers called tunica dartos. The scrotum provides a favorable environment of a lower temperature for the reproduction of spermatozoa. The scrotum is present in all domestic animals, is an out-pouching of skin from the abdominal region, and encloses the testes. It is thin, pliable, and relatively hairless as in horse and camel or hairy as in bull. By the last third of gestation in domestic animals, the testes are normally located in the scrotum. 2 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 Failure of the testes to descend into the scrotum results in a condition known as cryptorchidism. If both testes fail to descend (Bilateral cryptorchidism), it results in sterility. (Unilateral cryptorchidism) has a single descended testis; they are fertile but there is a tendency for this condition to be inherited, and the males possessing this trait should not be used for breeding. The scrotum consists of five layers from outside to inside as follows: 1. The outer layer (the skin or epidermis): is heavily populated with sweat glands to assist in maintaining proper testicular temperature. 2. Tunica dartos: consists of fibro-elastic tissue and smooth muscle, which is connected closely with the tunica vaginalis at the bottom of the scrotum. The scrotum consists of two pouches, which contain a testicle. The tunica dartos acts as a thermoregulatory by contracting to draw the testes close to the abdomen when cold and relaxing when the testes are warm. 3. Stratum subdarticum: a loosely woven layer of connective tissue between the tunica dartos and tunica vaginalis-parietal layer. This tissue allows the testes very free mobility in an upward and downward direction. 4. Parietal tunica vaginalis: (lines the scrotum) is continuous with the peritoneum. 5. Visceral tunica vaginalis: (covers the testis) is continuous with the peritoneum. 3 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 Table 1 Age of testicles descend into the scrotum Species Time Of Testical Descend Bull 3.5 _ 4 months of gestation Ram 40 _75 days Stallion Between 9 months of gestation and a few days after birth Boar After 85 days of gestation Tomcat 2-5 days after birth Between the last few days of gestation and the first few Dog days after birth Testes The tests (testicles) vary somewhat from species to species as far as shape, size, and location are concerned, but the essential structure is the same. Each testis consists of a mass of seminiferous tubules surrounded by a heavy fibrous capsule called the tunica albuginea. Many fibrous septa, or trabeculae, pass inward from the tunica albuginea to form a framework or stroma for support of the seminiferous tubules. 4 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 Figure 2 Structure of testis In all domestic animals except the horse, these trabeculae unite near the center of the gland to form a fibrous cord (Mediastinum testis). The cells of Leydig, which secrete the male hormone (testosterone), are located in the connective tissue between seminiferous tubules. The temperature of the tests to make its function properly should be less than body temperature (2-4c◦). These temperatures regulate by:  Muscles of the scrotum.  Muscles that cover the spermatic cord.  Circulating blood in the spermatic cord. 5 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 =================================================================== Epididymis The spermatozoa pass from the seminiferous tubules by way of the vasa efferentia to the head of the epididymis. The epididymis is a very long convoluted tube that connects the vasa efferentia of the testis with the vas deference or ductus deferens (33-35 m in bull, 50 m in boar, and 6 m in man). The head of the epididymis attaches to the same end of the testis that the blood vessels and nerves enter. The body of the epididymis parallels the long axis of the testis, and the tail of the epididymis continues as the ductus deferens, which doubles back along the body of the epididymis to the region of the head, where it enters the spermatic cord. The epididymis serves as a place for spermatozoa to mature before the time they are expelled by ejaculation. Spermatozoa are immature when they leave the testicle and must undergo a period of maturation within the epididymis before they are capable of fertilizing ova. =========================================================== Ductus Deferens (vas deferens) The ductus deferens (vas deferens) is a muscular tube that, at the time of ejaculation, propels the spermatozoa from the epididymis to the ejaculatory duct in the prostatic urethra, it's long about 45 cm. The ductus deferens leaves the tail of the epididymis, passes through the inguinal canal as a part of the spermatic cord, and at the internal inguinal ring turns caudally, separating from the vascular and nervous parts of the cord. 6 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 =================================================================== Spermatic Cord As the testis descends from the region caudal to the kidney, it brings with it the same blood, nerve, and lymphatic supply present in the embryo. These structures, the testicular vessels, and nerves, make up a large part of the spermatic cord that connects the testis with the rest of the body. The spermatic cord also includes the ductus deferens, which connect the tail of the epididymis with the prostatic urethra. =================================================================== Inguinal Canal The inguinal canal is a passage from the abdominal cavity to the exterior that extends from the internal inguinal ring to the external inguinal ring. The inguinal canal is potentially very extensive; it normally is only large enough to permit passage of the spermatic cord and inguinal vessels and nerves. If the internal ring and canal are too relaxed, a loop of the intestine may pass through the canal into the scrotum producing an inguinal hernia. =========================================================== Accessory Sex Glands The male accessory sex glands produce the bulk of the ejaculate or semen (the medium for transport of sperm). Semen provides favorable conditions for the nutrition of sperm and acts as a buffer against the natural acidity of the female genital tract. The accessory sex glands include the ampulla, seminal vesicles, prostate, and the bulbourethral (cowper's) glands. 7 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 1. Ampulla The ampulla is a glandular enlargement of the terminal parts of the ductus deferens. They are well developed in the stallion, bull, and ram; small in the dog; and absent in boar. The ampulla empties into the ductus deference and contributes fluid to the semen. 2. Seminal Vesicles (vesicular glands) The seminal vesicles formerly called (vesicular glands) are paired glands associated with the genital fold. They are lobulated (grapes-like) in bull, ram, and boar, but it is hollow (pear-shaped) sacks in the stallion. Each vesicular gland merges with the ipsilateral ductus deferens, creating the short ejaculatory duct, which empties into the pelvic urethra. The secretion of seminal vesicles form (20- 30%) contains a high concentration of fructose and sorbitol to nourish the sperms, and its gelatinous assist to lubricant urethra before ejaculation. 3. Prostate Gland The prostate gland is an unpaired gland that more or less surrounds the pelvic urethra, its shape was singly shaped like a walnut in dog and stallion. The prostate gland comprises various combinations of diffuse and compact parts extending along the pelvic urethra under the cover of the urethral muscles. The prostate produces an alkaline secretion, milky color contains phosphate lipids, Ca, Mg, and Na that gives semen its characteristic odor and form about (30-40%) of semen. In older intact animals, the prostate may become enlarged and interfere with urination. 8 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 4. Bulbourethral Glands The bulbourethral (formerly called Cowper's) glands are paired, bean-shaped, and placed on either side of the pelvic urethra just cranial to the ischial arch but caudal to the other accessory glands. Cowper’s glands secrete a viscous gelatinous secretion act to clean the urethra from urine remains and lubricant the penis before copulation. Table 2 the male sex accessory glands Species Prostate Seminal Vesicles Cowper's glands Ampulla Horse + + + + Ruminants + + + + Camel + + + + Pig + + + - Dog + - - + Cat + - + - + = present - = absent Penis The penis is the male organ of copulation that is composed essentially of erectile tissue. It is long, cylindrical a very much smaller in diameter. Sigmoid flexure just behind the scrotum forms an S-shaped curve, and its position is affected during erection. The penis presents three main parts: 1. Root: attached to the lateral parts of the ischial tuberosity. 2. Body: constitutes the bulk of the organ. 3. Glans Penis: the terminal part and free end of the organ. 9 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 Muscles of the penis: 1. Ischia Cavernous: Short but strong-paired muscle attaches the root of the penis to the ischial arch. Action: pulls the penis against the pelvis. 2. Corpus Cavernous penis: it forms the greater part of the bulk of the penis. 3. Corpus Cavernous urethra: it is also termed Corpus Spongiosum, and forms a tube around the urethra. 4. Bulbo Cavernous: present in a circular fashion around the proceeding muscle in a cross-sectional view. 5. Retractor Penis: comprises two strips that are the continuation of the suspensory ligament. Action: to withdraw the penis into the sheath/prepuce after erection. =========================================================== Prepuce The prepuce (or sheath) is an invaginated fold of skin surrounding the free extremity of the penis. The outer surface is typical skin, while the inner mucous membrane consists of a preputial layer lining the prepuce and a penile layer covering the surface of the free extremity of the penis. Male Urethra The male urethra is a long mucous tube, which extends from the urinary bladder to the glans penis. The urethra lies in a groove on the ventral surface of the corpus cavernous penis muscle. The urethra passes caudally on the floor of the pelvis, 10 Dr. Hussein Abbas Khamees, PhD. Theriogenology Department of Surgery and Theriogenology, College of Veterinary Medicine University of Al-Muthanna, Samawa, Iraq [email protected] 1 Male Fertility and Artificial Insemination | 1st semester | 5th year ‫نظري‬ 2024-2025 turns around the ischial arch, forming a sharp bend, and passes forward as a part of the penis, enclosed in the corpus cavernous urethra. =========================================================== Castration Castration is a term usually applied to the removal of the testis of the male, although technically it can apply to ovariectomy (removal of the ovaries) of the female animal as well. Early castration also improves the quality of meat animals by inhibiting undesirable secondary sex characteristics (notably the failure to develop marbling of muscle). Table 3 common terms for intact and castrated male animals Species Intact Adult Male Castrated Male Horse Stallion Gelding Ox Bull Steer Sheep Ram Wether Goat Buck Wether Pig Boar Barrow Chicken Rooster Capon 11