Sertoli cells provide nutrition for germ cells at all levels and play a role in maintaining and supporting them. It provides a suitable microenvironment for the differentiation and development of spermatogenic cells, supports the blood-testis barrier formed by cells, and prevents the antigens of spermatogenic cells from entering the blood circulation and causing immune response.
The production of sperm needs a suitable temperature. The temperature in scrotum is about 2℃ lower than that in abdominal cavity, which is suitable for the production of sperm. In the process of embryonic development, for some reason, the testis does not descend into the scrotum and stays in the abdominal cavity or groin, which is called cryptorchidism, so the seminiferous tubules cannot develop normally and do not produce sperm. If the testis of mature animals is heated or experimental cryptorchidism is carried out, the degeneration and atrophy of spermatogenic cells can be observed.
Newborn sperm is released into the curved vas deferens, which has no movement ability, but is transported to epididymis through the contraction of myoid cells around tubules and the movement of lumen fluid. In epididymis, sperm further mature and gain motor ability. A small amount of sperm can be stored in epididymis, and a large amount of sperm can be stored in vas deferens and its ampulla. During sexual activity, sperm is transported to the urethra through the peristalsis of the vas deferens. Sperm is mixed with the secretions of epididymis, seminal vesicle gland, prostate and urethral ball gland to form semen, which is ejected at orgasm. Normal men ejaculate about 3-6 ml of semen at a time, and each ml of semen contains about 20 million to 400 million sperm, less than 20 million sperm, which makes it difficult for eggs to fertilize.