1. Spermatogonia: The process starts with spermatogonia, which are diploid germ cells that undergo mitotic divisions to increase their number and form a pool of undifferentiated cells.
2. Primary Spermatocytes: Spermatogonia enter the first phase of meiosis, resulting in primary spermatocytes, which are still diploid.
3. Meiosis I: Primary spermatocytes undergo the first meiotic division, separating homologous chromosomes. It leads to the formation of two secondary spermatocytes, each carrying a haploid set of chromosomes (23 unpaired chromosomes in humans).
4. Secondary Spermatocytes: These haploid cells enter the second phase of meiosis.
5. Meiosis II: The second meiotic division of secondary spermatocytes results in four haploid spermatids. Each spermatid receives a unique combination of maternal and paternal chromosomes due to genetic recombination during meiosis.
6. Spermiogenesis: This final phase of spermatogenesis involves cellular changes and modifications that transform spermatids into mature spermatozoa. The spermatids develop an elongated head containing a condensed haploid nucleus and a long tail, enabling motility.
7. Mature Spermatozoa (Sperm): After spermiogenesis, the spermatozoa are released into the lumen of the seminiferous tubules and further transported through the epididymis, where they mature, gain the ability to swim (become motile), and are stored.
During ejaculation, mature sperm are expelled through the male reproductive tract, mixed with seminal fluid from various accessory glands, and form semen. Ejaculation delivers sperm into the female reproductive tract during mating or sexual intercourse, increasing the chances of fertilization by reaching the female gamete (egg).