Question

State the main function of seminiferous tubules.

Answer 1

Hint: In humans each testis weighs about 25 grams and is 4–5 cm long and 2–3 cm in diameter. Each is roofed by a fibrous capsule called the tunica albuginea and is split by partitions of fibrous tissue from the tunica albuginea into 200 to 400 wedge-shaped sections, or lobes.

Complete answer:
Within each lobe are 3 to 10 coiled tubules, called seminiferous tubules, which produce the sperm cells. The partitions between the lobes and also the seminiferous tubules both converge in one area near the anal side of every testis to make what's called the mediastinum testis.

The testes contain germ cells that differentiate into mature spermatozoa, supporting cells called Sertoli cells, and testosterone-producing cells called Leydig cells. The germ cells migrate to the fetal testes from the embryonic yolk sac. The Sertoli cells, which are interspersed between the germinal epithelial cells within the seminiferous tubules, are analogous to the granulosa cells within the ovary, and also the Leydig cells, which are located beneath the tunica albuginea, within the septal walls, and between the tubules, are analogous to the hormone-secreting interstitial cells of the ovary. The Leydig cells are irregularly shaped and commonly have quite one nucleus. Frequently they contain fat droplets, pigment granules, and crystalline structures; the Leydig cells vary greatly in number and appearance among the assorted animal species. They're surrounded by numerous blood and lymphatic vessels, similarly as by nerve fibres.

The seminiferous tubules, during which the sperm are produced, constitute about 90 percent of the testicular mass. Within the young male the tubules are simple and composed of undeveloped sperm-producing cells (spermatogonia) and also the Sertoli cells. Within the older male the tubules become branched, and spermatogonia become the fertile sperm cells after a series of transformations called spermatogenesis. The Sertoli cells found in both young and adult males mechanically support and protect the spermatogonia.

Note: Each tubule of the adult testis encompasses a central lumen, or cavity, which is connected to the epididymis and spermatic duct. Sperm cells originate as spermatogonia along the walls of the seminiferous tubules. The spermatogonia mature into spermatocytes, which mature into spermatids that mature into spermatozoa as they go in the central lumen of the tubule. The spermatozoa migrate, by short contractions of the tubule, to the mediastinum testis; they're then transported through a complex network of canals to the epididymis for temporary storage. The spermatozoa move through the epididymis and also the spermatic duct to be stored within the seminal vesicles for eventual ejaculation with the seminal fluid. Normal men produce about a million spermatozoa daily.