Human Anatomy - H. I. Koliadenko 2009

The Doctrine of the Viscera (Splanchnology)
Urogenital System
Male Genital Organs

The Internal Male Genital Organs include the Gonads (Testes with their epididymides), the Ductus deferens, Seminal Vesicles, Prostate Gland, and Bulbourethral Glands (Figs. 114, 115, 116).

The Testis, or testicle (testis), is a paired reproductive gland located within the Scrotum. It is ellipsoidal in shape, measuring 4–4.5 cm in length, 3–3.5 cm in width, 2–2.5 cm in thickness, and weighing 25–30 g. The testis features anterior and posterior margins, upper and lower poles, and medial and lateral surfaces. The Epididymis lies adjacent to the posterior margin of the testis. Externally, the testis is encased in a tough Connective Tissue capsule known as the tunica albuginea.

At the posterior border of the testis, the tunica albuginea thickens in a wedge-like fashion to form the Mediastinum testis. Connective tissue septa extend from the mediastinum, dividing the testis into 100 to 250 lobules. These septa form a structural framework enclosing smaller, cone-shaped lobules whose apices point toward the mediastinum testis and whose bases face the tunica albuginea.

Each lobule contains 3 to 4 convoluted seminiferous tubules, each 70–100 cm in length. Spermatozoa are produced within these convoluted seminiferous tubules. The convoluted tubules of a single lobule converge at the apex of the lobule within the mediastinum testis to form straight seminiferous tubules (tubuli recti). These straight tubules anastomose to form the rete testis, from which 15 to 18 efferent ductules emerge and lead into the HEAD of the epididymis.

The epididymis lies along the posterior border of the testis and is divided into a head, body, and tail. Within the head, the efferent ductules merge to form a single convoluted duct of the epididymis, which courses through the body and tail before continuing as the ductus deferens.

The ductus deferens (vas deferens) is a paired organ in the form of a cylindrical tube up to 50 cm long and up to 3 mm in diameter. It originates from the tail of the epididymis, ascends as part of the Spermatic Cord, and enters the Inguinal Canal through its superficial ring. From the inguinal canal, it passes through the deep inguinal ring toward the Urinary Bladder, running along the lateral and subsequently the inferior wall of the pelvis. Approaching the urinary bladder and prostate gland, the ductus deferens dilates to form an ampulla, then joins the duct of the Seminal Vesicle to form the ejaculatory duct.

Class="center">

Fig. 114. Male Genital Organs:

1 — Abdominal Aorta; 2 — left common iliac artery; 3 — sacral promontory; 4 — left Ureter; 5 — rectum; 6 — seminal vesicle; 7 — prostate gland; 8 — anal sphincter; 9 — testis; 10 — scrotum; 11 — epididymis; 12 — prepuce of Penis; 13 — glans penis; 14, 20 — ductus deferens; 15 — corpus cavernosum of penis; 16 — corpus cavernosum of Urethra; 17 — spermatic cord; 18 — membranous urethra; 19 — pubic bone; 21 — Peritoneum; 22 — urinary bladder; 23 — external iliac artery and vein; 24 — left common iliac vein; 25 — right common iliac artery; 26 — INFERIOR VENA CAVA

Fig. 115. Sectioned testis with epididymis

1 — spermatic cord; 2 — ductus deferens; 3 — pampiniform plexus; 4 — mediastinum testis; 5 — testicular tunics; 6 — testicular septa; 7 — testicular lobules; 8 — sinus of epididymis; 9 — head of epididymis

The wall of the ductus deferens consists of three layers: an inner mucous membrane (mucosa), a middle muscular layer (muscularis), and an outer adventitial layer (adventitia). The mucosa is lined with columnar epithelium. The muscular layer is thick and robust, comprising inner and outer longitudinal layers of smooth Muscle enclosing a middle circular layer. The adventitia is composed of connective tissue interspersed with elastic fibers, housing Blood Vessels and nerve fibers.

The seminal vesicle is a paired organ situated posterior to the Cytology/practical/108.html">Fundus of the urinary bladder and anterior to the rectal ampulla. It is elongated in shape, 4–5 cm long and up to 2 cm wide, with a highly convoluted and compartmentalized Structure. The upper portion of the seminal vesicle is dilated, while the lower portion narrows into an excretory duct that merges with the ampulla of the ductus deferens to form the ejaculatory duct. The right and left ejaculatory ducts converge, penetrate the substance of the prostate gland, and open into the initial segment of the urethra.

The seminal vesicles serve as a reservoir for spermatozoa, which pass from them first into the ductus deferens, then into the ejaculatory duct, and subsequently into the urethra. The seminal vesicles are also filled with a secretion produced by the mucosal lining of their internal surface.

Fig. 116. Male genital organs:

1 — muscular coat of urinary bladder; 2 — submucosa of urinary bladder; 3 — trigone of bladder; 4 — internal urethral orifice; 5 — prostate gland; 6 — urethral gland; 7 — Bulbourethral gland; 8 — corpus cavernosum of penis; 9 — tunica albuginea; 10 — glans penis; 11 — prepuce; 12 — external urethral orifice; 13 — corpus spongiosum of urethra; 14 — crus of penis; 15 — membranous urethra; 16 — prostatic ducts; 17 — right ureteral orifice; 18 — fold of urinary bladder mucosa; 19 — right ureter

The prostate gland (prostata) is an unpaired muscular-glandular organ shaped like a chestnut and weighing approximately 20 g. Located in the lesser pelvis, the gland completely encircles the initial portion of the urethra. Anteriorly, it lies adjacent to the Pubic Symphysis, and posteriorly, to the rectal ampulla. The prostate consists of two lobes connected by an isthmus. Its mass and dimensions vary with age: it is small in children and reaches full development by the age of 17, but in old age it may enlarge to the size of a chicken egg.

The glandular tissue of the prostate surrounds the prostatic urethra and comprises 30 to 50 branching ducts that open into the posterior wall of the urethra. At this site, the URINARY AND REPRODUCTIVE tracts converge. The prostatic secretion, produced by the glandular mucosa, enhances sperm motility.

The bulbourethral gland is a paired, yellowish-brown, pea-sized organ located posterior to the membranous urethra. The excretory ducts of these glands are up to 6 cm long and open into the urethral lumen. The secretion of these glands, a viscous mucous fluid, mixes with seminal fluid within the ejaculatory duct.

External Male Genital organs

The penis (penis) is an unpaired cylindrical organ.

The penis is anatomically divided into a ROOT, body (shaft), and glans. The root of the penis is externally covered by the Skin of the scrotum and anchored to the anterior surface of the pubic bones. The body of the penis presents an anterior surface, known as the dorsum of the penis, and a posterior urethral surface.

The glans forms the free, cone-shaped terminal end of the penis, at the apex of which opens the external urethral orifice. The glans is separated from the body of the penis by a shallow sulcus (neck). It represents the continuation and distal expansion of the corpus spongiosum of the urethra.

The structure of the penis is primarily based on two paired corpora cavernosa and one corpus spongiosum. The two upper corpora cavernosa are joined together, forming a groove on their lower surface that houses the corpus spongiosum of the urethra. All three penile structures (the corpora cavernosa and the corpus spongiosum) are enclosed externally by deep and superficial fasciae, over which lies a thin, easily movable skin. Only on the glans penis is the skin firmly fused with the tunica albuginea and immobile. In the region of the glans, the skin forms a free fold known as the prepuce, or foreskin. On the lower surface of the glans, the anterior skin fold is connected to the skin of the glans by the frenulum.

The corpora cavernosa consist of numerous connective tissue septa containing smooth muscle fibers. These fibers surround the cavernous spaces (caverns), within the walls of which blood vessels branch out. During an erection, the caverns of the corpora cavernosa fill with blood, while its outflow through the Veins ceases due to their constriction and compression by the Muscles. The corpora cavernosa and the urethra straighten, facilitating the discharge of seminal fluid and urine.

The scrotum is a cutaneous sac-like structure divided by a connective tissue septum into two chambers—one for the right and one for the left testis. The scrotal skin is covered with sparse Hair, which transitions into dense hair in the pubic region. The skin contains numerous sweat and Sebaceous Glands, while beneath it lies a layer composed of a network of smooth muscle fibers. It fuses with the skin via numerous septa, and its contraction causes The formation of folds on the scrotum.

Embryogenesis OF THE Male Genital Organs

The reproductive organs develop from the primitive Kidney. In the second month of embryonic development, on the medial surfaces of the primitive Kidneys—known as the Wolffian bodies—gonadal primordia emerge as oval-shaped ridges called genital folds. Initially, they are indifferent, as it is impossible to determine the sex from them.

At the end of the 2nd month of embryonic development, sexual Differentiation of the gonadal primordia begins. In a male embryo, the epithelial cords derived from the germinal epithelium elongate significantly and transform into convoluted seminiferous tubules. The seminiferous tubules connect with the urinary tubules of the primitive kidney, and through them, with the mesonephric duct, which develops into the duct of the epididymis, the vas deferens, and the seminal vesicles.

The testis forms from the germinal epithelium anterior to the kidneys, passing through the anterior abdominal wall beneath the skin and pushing ahead of it all the layers of the abdominal wall. These subsequently form the Tunics of the testis, while the skin sac transforms into the scrotum. The genital tubercle gives rise to the penis.

Age-Related Structural Features of the Male Genital Organs

In newborns, the reproductive organs are in a developing state. Until Puberty, the testis and its epididymis develop very slowly. In a newborn child, the mass of the testis is 0.2 g, at 1 year — 1 g, at 13–14 years — 2 g, at 16 years — 7–8 g, and in an adult — 20–30 g.

The prostate gland in a newborn is small and consists predominantly of muscular and connective tissue, with almost no glandular tissue. Accelerated growth of the prostate occurs during puberty due to the proliferation of its glandular component. The gland begins to perform its secretory function at age ten; during puberty, the penis grows rapidly.

After the age of 50–55, Atrophy of the glandular portion of the prostate is observed, and by 55–60 years, the secretion of its fluid decreases. The mass of the prostate diminishes to 12–15 g due to the atrophy of glandular tissue. Frequently in elderly individuals, the prostate enlarges As a result of connective tissue proliferation.