siittiötuotannon

Siittiötuotanto, also known as spermatogenesis, is the biological process by which sperm cells are produced. This complex process occurs in the seminiferous tubules of the testes in males. It begins during puberty and continues throughout a man's life, although the rate of production may decline with age.

The process starts with diploid germ cells called spermatogonia. These cells undergo mitosis to produce more spermatogonia and also differentiate into primary spermatocytes. Primary spermatocytes then enter meiosis I, a type of cell division that reduces the chromosome number by half, resulting in two haploid secondary spermatocytes. Each secondary spermatocyte then undergoes meiosis II, producing two haploid spermatids.

Spermatids are immature sperm cells that are not yet capable of fertilization. They undergo a further differentiation process called spermiogenesis, where they develop a head containing the genetic material, a midpiece packed with mitochondria for energy, and a tail or flagellum for motility. The mature, motile cells are then called spermatozoa, or sperm.

Spermatogenesis is tightly regulated by hormones, primarily follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland, which in turn are influenced by gonadotropin-releasing hormone (GnRH) from the hypothalamus. Testosterone, produced by the Leydig cells in the testes, also plays a crucial role in supporting spermatogenesis. The entire process, from spermatogonium to mature sperm, takes approximately 64 to 74 days in humans.