Definition:
Production of male sex gametes, or spermatozoa, through the process of meiosis.

Description:

During embryonic development, germs cells migrate from the yolk sac to the testes to become spermatogonia. Spermatogonia are dipolid cells (46 chromosomes) that give rise to haploid (23 chromosomes) gametes (sex cells) through the process of meiosis. In meiosis, each chromosome duplicates itself as in mitosis; however, the homologous chromosomes remain attached and lie alongside one another in pairs, producing a tetrad of four chromatids. Two matruation divisions are required to separate the tetrad into four spermatids, each with a hapoid number of chromosomes. EAch spermatid develops into a matrure spermatoozoon.
The seminiferous tubules contain sustentacular (Sertoli) cells which envelop the developing spermatoz providing them with nourishment. Sustentacular cells also contain FSH receptors and therefore mediate the effect of FSH uint the testis. If a male is healthy, spermatogenesis is continuous from puberty, although it lessens in old age. A healthy male produces several hundred million spermatozoa each day.

Clinical Information

Male infertility. The inability of the sperm to fertilize the ovum because of inadequate production of viable sperm. Possible causes include: alcoholism, dietary deficiencies, local injury, variococele, excessive heat, exposure to X rays, or hormonal imbalance.