FSH (follicle – stimulating hormone) and LH (luteinizing hormone) are the hormones which are stimulated by hypothalamic gonadotrophin – releasing hormones (GnRH) and produced by anterior pituitary. FSH stimulates Stertoli cell (also known as the nurse cell) to stimulate spermatogenesis while LH acts on the Leydig cell to produce testosterones - the major androgen, and also one of two main hormones control the spermatogenesis. Before puberty, especially during the fetal development, testosterone is produced for the development of male sex organs but it is secreted in the low levels and FSH is inhibited by Inhibin to prevent spermatogenesis. During puberty, testosterones level is rising and enter to spermatogenesis to complete the meiosis division and prepare for the mature of spermatids. After that, at the maturation stage of spermatids to form spermatozoa, FSH acts on Stertoli cell to initiate the spermatogenesis together with testosterones. After the puberty, FSH is not needed for continuation of spermatogenesis any more.
Image from: Widmaier, Eric.P, Raff, Hershel & Strang, Kevin T. (2008) Vander’s human physiology: Mechanisms of body function, Eleventh Edition, America, New York: McGraw – Hill, pp611
Apart from two hormones above, there are some hormones, which do not direct affect to spermatogenesis, but have certain affects on process of secreting FSH and testosterones. These are GnRH (hypothalamic gonadotrophin – releasing hormones), LH (luteinizing hormone), Inhibin and the protein called androgen – binding protein. GnRH is the hormones synthesized in the hypothalamus and the first hormones in the chain of the hormonal controls of all male reproductive system. Through the hypothalamo – pituitary portal vessels, in the anterior pituitary, GnRH stimulates the release of the anterior pituitary to secrete FSH and LH. While FSH has a function is stimulating spermatogenesis, LH acts primary on the Leydig cell (also called interstitial cells) to synthesize and release testosterone. Both GnRH and LH secretions are inhibited by negative feedback effects of testosterones. When the level of testosterones is rising (the normal level of testosterones in male is 300 -1,200 ng/dL = nanograms per deciliter), GnRH production from hypothalamus will decrease, make the reduction of LH, or the negative feedback will affect directly in anterior pituitary, reduce the secretion of LH and then, testosterones secretion is decreasing. Conversely, testosterone level decreases will stimulate the hormones secretion in hypothalamus and anterior pituitary; make the production of GnRH and LH increase. About FSH secretion, this hormones level is controlled by Inhibin. Inhibin is the protein hormones, which is secreted by Stertoli cell, have a negative feedback for anterior pituitary glands to inhibit FSH release. One of the most important role of Inhibin is inhibit FSH releasing and maintain FSH level at 0 - 5.0 mIU/ml (milli international units per milliliter) before puberty to prevent spermatogenesis. After puberty, the FSH level is maintaining at 1.5 - 12.4 mIU/ml. If this level is rising or reducing, FSH will stimulate or inhibits the Stertoli to release more or less Inhibin to control FSH secretion. Final chemicals can affects the two hormones which controls spermatogenesis is Androgen – binding protein (ABP). This is the protein produced by Stertoli cell to binding all testosterone secretion from the Leydig cell to maintain the concentration of testosterones high enough in lumen to initiate and stimulate spermatogenesis (can be higher than in blood 20-25 times).
The hormonal controls of spermatogenesis play important role in male reproductive system. By secreting specialized hormones for stimulating spermatogenesis with different levels of different hormones in different periods of life, the hormonal controls the function of male reproductive system and produce spermatozoa. From that point, scientists find out the way to cure disorders of male reproductive system, such as Genital functional disorders in male, spermatogenesis disorders, or more important, is Childless in male (especially in the case which LH level is the main reason for Childless). Furthermore, we may have hormones test to find out which hormones is in abnormal-level, thence with drugs and function foods, we can prevent or cure the disease as soon as possible, before the illness become too serious.
(816 words)
Reference list:
Fox, Stuart Ira (2002) Human Physiology, Seventh Edition, America, New York: McGraw – Hill
Katz, VL, Lentz, GM., Lobo, RA & Gershenson, DM. (2007) Comprehensive Gynecology, Fifth Edition, Philadelphia: Mosby Elsevier.
Martini, Frederic H., Bartholomew, Edwin F (2010) Essentials of ANATOMY & PHYSIOLOGY, Fifth Edition, San Francisco: Pearson Education, Inc.
McPherson, RA and Pincus, MR. (2006) Henry's Clinical Diagnosis and Management by Laboratory Methods, 21st Edition, Philadelphia: Saunders Elsevier.
Widmaier, Eric.P, Raff, Hershel & Strang, Kevin T. (2008) Vander’s human physiology: Mechanisms of body function, Eleventh Edition, America, New York: McGraw – Hill.
