Spermatogenesis is a very complex process of cell division and differentiation that is accomplished in the male gonads, the testes, which are the site of spermatogenesis, and the epididymis, which is the organ of sperm maturation. Spermatogenesis requires several steps: prepubertal testicular development, puberty initiation, and the process of spermatogenesis Prepubertal testicular development: The gonads are not yet sexually differentiated in the sixth week of the human embryo, but by the seventh week the gonads begin to sexually differentiate and the male individual gradually differentiates to form the testes. In the second month of the human embryo, the testes descend about 10 body segments, and by the beginning of the third month, the testes are positioned near the superior inguinal canal and remain there until the 28th week of the human embryo, and most human embryos enter the scrotum only at 7-8 months. After the testes descend into the scrotum, the channel between the peritoneal cavity and the sheath cavity is gradually occluded and usually disappears at birth or shortly after birth; if it fails to occlude, it causes congenital inguinal hernia. If one or both testicles still do not descend into the scrotum within 3~5 months after birth, it is called cryptorchidism. Initiation of puberty: There is no strict boundary for male pubertal development, which usually lasts for 2 to 4 years from the age of 10 to 14. At the beginning of puberty, the testes develop and enlarge rapidly, and the spermatogenesis process is initiated. Regulation of puberty initiation by the hypothalamic-pituitary-gonadal axis. Spermatogenesis process: Spermatogenic cells during spermatogenesis can be divided into the following stages: primitive A spermatogonia, A spermatogonia, B spermatogonia, primary spermatocytes (pre-fine line stage spermatocytes, fine line stage spermatocytes, even line stage spermatocytes and coarse line stage spermatocytes) secondary spermatocytes, round spermatocytes, condensed stage spermatocytes and spermatozoa, and spermatogenesis culminating in the formation of spermatozoa. After developing into complete spermatozoa in the testes, they still need to undergo a period of maturation and development in the epididymis before reaching a truly mature spermatozoon with motility.