Question No.  3104 :
How are sperm produced and how long do they take to become mature? Roughly, how many sperm are there per ejaculation?

Spermatogenesis begins at puberty and the undifferentiated germ cells, which are termed spermatogonia, begin to divide mitotically. The daughter cells of this first division then divide, and so on for a specified number of division cycles so that a clone of spermatogonia is produced from each original spermatogonium. The cells that result from the final mitotic division and differentiation in the series are called primary spermatocytes, and these are the cells that will undergo the first meiotic division of spermatogenesis. Each primary spermatocyte increases markedly in size and undergoes the first meitotic division to form two secondary spermatocytes, each of which in turn undergoes the second meitotic division into spermatids. The final phase of spermatogenesis is the differentiation of the spermatids into spermatozoa (sperm). The entire process, from primary spermatocyte to mature sperm, takes approximately 64 days. After formation within the testes, the sperm move through its tubules to a nearby long, coiled tube called the epdidymis that sits on the back side of the testes. Here the sperm undergo further development and may be stores for 18 hours to 10 days, becoming capable of propelling themselves and penetrating an oocyte. The sperm then move toward a connecting tube, the vas deferens, a long tube that ascends from the epididymis into the pelvic cavity, looping over the side of the urinary bladder. Stored in the epididymis and the very beginning of the vas deferens, sperm retain their ability to fertilise an oocyte for a short while. If they are not ejaculated, "old" sperm are reabsorbed by the body to make room for "new" sperm. The normal human male produces approximately 300 million mature sperm per day. Once ejaculation has occurred, there is a latent period before the second one could occur. The latent period is quite variable but may last from minutes to hours. The volume and sperm content of the ejaculate depend on the length of time between ejaculation. An average human ejaculate contains about 180 million sperm. For a summary of mammalian spermatogenesis, please refer to the following Web page: http://www.path.cam.ac.uk/~na/sperm.html Question Asked By:

Name: tiffany

Age Group: 13 to 20

Occupation Type: Sales and Marketing

Education Level: Diploma