Leánsejtek

Leánsejtek, also known as Leydig cells or interstitial cells of the testes, are endocrine cells found in the interstitial tissue of the testes. Their primary function is to produce and secrete androgens, the most important of which is testosterone. These cells are crucial for the development and maintenance of male reproductive tissues, as well as for the appearance of secondary male sex characteristics.

Leydig cells originate from mesenchymal stem cells in the embryonic gonad. During fetal development, they are stimulated by human chorionic gonadotropin (hCG) to produce testosterone, which is essential for the differentiation of male internal and external genitalia. After birth, testosterone production by Leydig cells significantly decreases until puberty.

At puberty, luteinizing hormone (LH), secreted by the anterior pituitary gland, stimulates Leydig cells to resume robust testosterone production. This surge in testosterone drives the maturation of the male reproductive system and the development of secondary sexual characteristics such as deepened voice, facial hair, and increased muscle mass. Leydig cells also play a role in spermatogenesis, the process of sperm production, by providing an adequate local concentration of testosterone within the seminiferous tubules.

The activity of Leydig cells is regulated by a negative feedback loop. High levels of testosterone inhibit the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus and LH from the pituitary, thus reducing further testosterone production. Conversely, low testosterone levels stimulate GnRH and LH release. Leydig cells are also influenced by other hormones and local factors.