Testosterone in the testes is under the pulsatile control of the pituitary luteinizing hormone. Leydig cells secrete this hormone. The cyclic nucleotide phosphodiesterase (PDE) is modulated by the response to LH. The presence of PDEs in Leydig cells is not fully defined. In Leydig cells, PDE8A is expressed and is a crucial regulator of LH signalling and steroidogenesis. In a Leydig cell isolated from PDE8A knockout mice, a four-fold increase in the sensitivity of LH for Testosterone production was detected. These cells are named after the great German anatomist Franz Leydig, who discovered them between 1850 and 1851.
During the 1930s, the male hormone was shown to be androgen or testosterone, its endocrine actions were studied extensively, and the role of the pituitary gland in regulating testicular function was demonstrated. From the 1931s through the 1951s, Leydig cells came back into favour as endocrine cells, although some uncertainty persisted, and there was still no direct evidence that Leydig cells produced androgen. The direct evidence came from histochemistry in 1957 and biochemistry in 1964.
Franz Leydig first described the testicular cells in 1851 that now bears his name. Their evidence seemed compelling at the time but was necessarily circumstantial because there was no direct proof that Leydig cells produced a male androgenic hormone. Over the following decades, workers found additional evidence that these cells had an endocrine function, but other findings cast doubt on the hypothesis, and increasing skepticism developed about the earlier evidence. Many influential reproductive biologists suspected that the seminiferous tubules were the actual source of male hormones.
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The interstitial cell of Leydig is stimulated by LH when it enters the testes to make and release testosterone into the testes and the blood. It appears in men during adolescence and stimulates spermatogenesis. Many external characteristics that grow in an individual due to the production of this hormone are deepening of the voice, facial hair growth, axillary and pubic hair growth.
To inhibit the release of GnRH, FSH, and LH, a negative feedback system occurs in males with levels of testosterone rising. It affects the hypothalamus and anterior pituitary for those releases. When the sperm count is too high, inhibit hormone is produced by sterling cells in the blood. To slow down spermatogenesis, GnRH and FSH are released. The release of sterling decreases if the sperm count becomes 23million/ml. This was how the interstitial cells of Leydig were responsible for the production and secretion of testosterone.
The table below precisely describes the difference between Sertoli cells and Leydig cells.
Leydig cells function was made easy to understand by the introduction of important methodology approaches of Larry Ewing. It first started in 1850 when rabbits' testicles were experimented on, and it led to the production of testosterone. Adult Leydig cells produce progesterone more than testosterone. They respond differently to gonadotropin treatments. Leydig cells respond very slowly to these gonadotropins and produce 20 to 30 times fewer steroids than adrenal cells. Leydig cell's function is well observed in uncompromising three-dimensional testis architecture. From 1850, it took over a century to discover the proper functions of Leydig cells.
The primary source of androgen and testosterone in males is Leydig cells. These cells are associated with decreased ratios of testicular hormones to gonadotropins and are more frequent in biopsies with impaired spermatogenesis. Thus micronodules are a marker of testicular failure in men and also in Leydig cells histology.
1. Define Leydig cells briefly in your words.
Leydig cells can be defined as cells situated in the interstitial testicular tissue whose primary function is to produce testosterone. Leydig cell secretes testosterone, androgen under the influence of luteinizing hormone. Luteinizing hormone is released from the pituitary gland under the reaction of the Gonadotropin-releasing hormone.
There are two types of Leydig cells: one is Fetal Leydig cells, and another is adult Leydig cells, and these Leydig cells function differently. Fetal Leydig cells function in the fetus but largely degenerate soon after birth, and the adult Leydig cells secrete testosterone which is needed for male reproduction. But Fetal and adult Leydig cells are different as they appear to have distinct gene expression profiles. Leydig cells secrete androgen, which is vital for the male reproductive role, and it develops in the fetal stage. In different living organisms like mice, cells exhibiting steroidogenic factors bring about the fetal Leydig cells.
2. What are the roles of Leydig Cells?
Leydig cells are cells that play an essential role in male reproduction. Some of the essential roles of Leydig cells are as follows.
Leydig cells secrete testosterone to upkeep spermatogenesis and extra testicular anabolic functions.
Leydig cells secrete androgen, which helps in the development and maintenance of the reproductive tract and assists an important function in male reproduction.
Leydig cells can proliferate the testis after their consumption via ethylene methanesulfonate, even in adults.
Leydig cells secrete paracrine factors that help to balance the function of Sertoli cells, which helps in the generation of germ cells and plays an important role in spermatogenesis.
Leydig cells function in order to develop masculinization in the male fetus and help to grow male genital parts.
Fetal Leydig cells function in the fetus, and after birth, they are placed in the interstitium of testis after sex determination.