Human Anatomy - Kotsan I. Ya. 2009

Urogenital System
Genitals - Male Genitals
Testis

The testis (orchis in Greek) is a paired male reproductive gland classified as a gland of mixed secretion. The exocrine function of the testis is The production of male Gametes (spermatozoa), while its endocrine function involves the Synthesis of male Sex Hormones, which enter the bloodstream and influence The Development of Primary and secondary sex characteristics, The Musculoskeletal System, and human psychological development.

The Testes are located in the perineal region within a specialized sac known as the Scrotum. Typically, the left testis hangs slightly lower than the right. The testes are separated by the scrotal septum and enclosed within tunics. On average, a testis measures approximately 4 cm in length, 3 cm in width, and 2 cm in thickness, with a mass of 20–30 g. It has a firm consistency, an oval shape, and is slightly flattened laterally. It presents two surfaces—the lateral surface (facies lateralis) and the medial surface (facies medialis); two borders—the anterior border (margo anterior) and the posterior border (margo posterior); and two extremities—the superior extremity (extremitas superior) and the inferior extremity (extremitas inferior). A small appendage, the Appendix of testis (appendix testis), is frequently found at the upper pole of the testis, representing a remnant of the cranial end of the paramesonephric duct.

Class="center">

Fig. 173. Male pelvic Organs (after R. D. Sinelnikov)

1 — mesocolon of the sigmoid colon; 2 — rectum; 3 — rectouterine pouch; 4 — ampulla of rectum; 5 — ampulla of Ductus deferens; 6 — Seminal Vesicle; 7 — transverse rectal fold; 8 — coccyx; 9 — levator ani Muscle (pelvic Diaphragm); 10 — middle lobe of prostate; 11 — posterior part of right lobe of prostate; 12 — ejaculatory duct; 13 — external anal sphincter; 14 — internal anal sphincter; 15 — anus; 16 — sphincter urethrae muscle; 17 — bulbospongiosus muscle; 18 — bulb of Penis; 19 — scrotal septum; 20 — prepuce of penis; 21 — external urethral orifice; 22 — navicular fossa of Urethra; 23 — glans penis; 24 — corona of glans; 25 — corpus cavernosum of penis; 26 — spongy urethra; 27 — membranous urethra; 28 — deep transverse perineal muscle; 29 — seminal colliculus; 30 — anterior part of right lobe of prostate; 31 — internal urethral orifice; 32 — mucous membrane of Urinary Bladder; 33 — muscular coat of urinary bladder; 34 — lateral umbilical fold; 35 — Peritoneum; 36 — ductus deferens (relief); 37 — external iliac artery and vein (relief); 38 — sacral promontory; 39 — fifth lumbar vertebra; 40 — Ureter (relief); 41 — sacrum

Structure OF THE testis. Externally, the testis is covered by a dense, thick whitish Connective Tissue capsule known as the tunica albuginea (Fig. 174). Beneath this capsule lies the parenchyma of the organ (parenchyma testis). From the inner surface of the posterior border of the tunica albuginea, a roller-shaped connective tissue projection extends into the parenchyma—the Mediastinum testis—from which connective tissue septa (septula testis) radiate in all directions. These septa reach the tunica albuginea on the opposite side of the testis, dividing the organ's parenchyma into testicular lobules (lobuli testis). The lobules are conical in shape, with their apices directed toward the mediastinum and their bases toward the tunica albuginea. Each testis contains between 250 and 300 lobules.

Fig. 174. Diagram of The structure of the testis and Epididymis

1 — ductus deferens; 2 — efferent ductules of testis; 3 — duct of epididymis; 4 — mediastinum testis; 5 — rete testis; 6 — straight seminiferous tubules; 7 — testicular septa; 8 — convoluted seminiferous tubules; 9 — anastomoses between seminiferous tubules of different lobules; 10 — tunica albuginea; 11 — lobules of epididymis

Each testicular lobule consists of 2–3 convoluted seminiferous tubules (tubuli seminiferi contorti) and interstitial tissue, which is densely vascularized by Blood and Lymphatic capillaries and Functions as an endocrine gland, producing Male Sex Hormones (androgens). Within the convoluted tubules, whose walls contain spermatogenic epithelium, the proliferation, growth, and maturation of Male Germ Cells (spermatozoa) take place. Each tubule measures 50–80 cm in length, with the total length of all tubules in a single testis reaching approximately 300–400 m. As they course toward the mediastinum testis, the convoluted seminiferous tubules converge at the apices of the lobules to form short straight seminiferous tubules (tubuli seminiferi recti). The straight tubules empty into the rete testis, located within the substance of the mediastinum testis. From the rete testis, 12–15 efferent ductules of the testis (ductuli efferentes testis) emerge, extending toward the epididymis and opening into the duct of the epididymis.