MALE REPRODUCTIVE SYSTEM

      

            The male reproductive system consists of the testes, epididymides, ductus deferentia, urethra, seminal vesicles, prostate gland, bulbourethral glands, scrotum, and penis. Scrotum contains the testes and is divided into two internal compartments by a connective tissue septum. The outer layer of the scrotum includes the layer of superficial fascia consisting of loose connective tissue and two kinds of muscles, they are dartos muscle and cremaster muscle, their work is influenced by temperature. Perineum is the area between the thighs, it is divided into two triangles, they are the anterior or urogenital triangle contains the base of the penis and scrotum, and the small posterior or anal triangle contains the anal open.

Testes

The testes are develop as retroperitoneal organs in the abdominopelvic cavity and are connected to the scrotum by a fibromuscular cord called the tubernaculum. The testes move from the abdominal cavity through the inguinal canal to the scrotum.  As they move into the scrotum, the testes are preceded by out -pocketing of the peritoneum called the process vaginalis. The inferior part of  process vaginalis remains as a small, closed sac, the tunica vaginalis which covers most of the testis.The testes are the small ovoid organs within the scrotum act as exocrine (secrete sperm) and endocrine (secrete testosterone) glands. The outer part of each testis is a thick, white cap called the tunica albugenia. Incomplete septa divides each testis into about 300-400 lobules. The substance of testis between the septa include two types of tissue; seminiferous tubules in which sperm cells develop; and a loose connective tissue stroma that surrounds tubules and contains clusters of endocrine cells called interstitial cells or Leydig cells, which secrete testosterone. The seminiferous tubules empty in tubular network called the rete testis. The rete testis empties into 15-20 tubules called efferent ductules which then help move sperm cells out of testis with their ciliated pseudostratified columnar epithelium.

Epididymis

The efferent ductules from each testis become extremely convoluted and form a comma-shaped structure on the posterior side of the testes called the epididymis (plural, epididymides). The epididymis has a pesudostratified columnar epithelium with microvili called stereocilia which functions to increase the surface area of epithelial cells to absorb fluid from the ductus epididymis. Each epididymis consists of: a head that contains convoluted efferent which empty into a single convoluted ductus epididymis; a body contains of  ductus epididymis; and a long tail which is located in the inferior border of testis. The final maturation of the sperm cells occurs within the ductules of epididymides.

Ductus deferens

The ductus deferens has a pesudostratified columnal epithelium and is surrounded by smooth muscle that helps propel the sperm cells through the ductus deferens by its peristaltic movement. Ductus deferens or vas deferens emerges from the tail of the epididymis and associated with the blood vessels and nerves that supply the testis. These structures and their coverings constitute the spermatic cord which consists of the ductus deferens, testicular artery and venous plexus, lymph vessels, nerves, fibrous remnantsof the process vaginalis, and three coats (external spermatic fascia, the cremaster muscle, and the internal spermatic fascia). The spermatic cord passes obliquely through the inferior abdominal wall by way of the inguinal canal. The end of ductus deferens enlarges to form ampulla.

Ejaculatory duct

Adjacent to the ampulla of each ductus deferens is a sac-shaped gland that is called seminal vesicle. A short duct from the seminal vesicle joins the ductus deferens to form the ejaculatory duct. These ducts project into the prostate gland and end by opening into the urethra. The male urethra extends from the urinary bladder to the distal end of the penis and it is the passageway of both urine and male reproductive fluids. The urethra can be divided into three parts: the prostatic urethra closest to the bladder and passes through the prostate gland, it is where the ejaculatory duct and prostate gland empty their contents, it is mostly lined by transitional epithelium; the membranous urethra is the shortest part of urethra and extends from the prostatic urethra through the urogenital diapraghm which is part of the muscular floor of the pelvis; the spongy urethra (penile urethra) is the longest part of the urethra and extends from the membranous urethra through the length of the penis, near its opening is lined by stratified squamous epithelium. Urethral glands secrete several mucous into urethra.

Penis

The penis is the male organ of copulation and transfers sperm cells from the male to the female. Penis consists of three columns of erectile tissue, two of the erectile columns are called the corpora cavernosa, that expands to form a crus of the penis; the third column called corpus spongiosum, expands over the distal end of the penis to form the glans penis, the spongy urethra passes through corpus spongiosum and opens as the external urethral orifice and at the base of the penis forms the penis bulb. Together these structures constitute the root of the penis and attach penis to the coxae. Engorgement of this erectile tissue with blood causes the penis to enlarge and become firm, a process called erection.

The shaft of the penis is covered by skin that is loosely attached to the connective tissue surrounding the penis but firmly attached at the base of the glans penis, and a thinner skin layer tightly covers the glans penis. The skin of the penis especially the glans penis is well supplied with sensory receptors. A loose fold of skin called the prepuce (foreskin) covers the glans penis. A single midline dorsal vein is flanked on each side by dorsal arteries with dorsal nerves lateral to them. Additional deep arteries lie within the corpora cavernosa.

Accessory glands

The seminal vesicles are sac-shaped glands located next to the ampullae of the ductus deferens. Each gland tapers into a short duct that joins the ductus deferens to form the ejaculatory duct. The prostate gland consists of both glandular and muscular tissue and is about the shape and size of a walnut. The prostate gland is dorsal to the symphysis pubis at the base of the bladder, where ut surrounds the prostatic urethra and the two ejaculatory ducts. The gland is composed of an indistinct smooth muscle capsule and numerous smooth muscle partitions that radiate inward toward the urethra. Covering these muscular partitions is a layer of columnar epithelial cells that form saccular dialtions into which the cells secrete prostatic fluids; 20-30 small prostatic ducts transport these secretions into the prostatic urethra. The bulbourethral glands are a pair of small glands located near the membranous part of the urethra. In young males each is about the size of a pea, but they decrease in size with age. Each gland is a compound mucous gland. The small duct of each gland unites to form a single duct and then enters the spongy urethra at the base of the penis.