How Do Leydig Cells Influence Male Hormones and Reproductive Health?
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.
Leydig Cells Histology
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.
Difference Between Sertoli cells and Leydig cells
The table below precisely describes the difference between Sertoli cells and Leydig cells.
Leydig Cells Function
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.
FAQs on Leydig Cells: Histology, Functions & Significance
1. What are Leydig cells and where are they located in the human body?
Leydig cells, also known as interstitial cells, are specialised endocrine cells found in the male testes. They are located in the soft connective tissue present in the spaces between the seminiferous tubules. Their strategic position allows them to release hormones directly into the bloodstream.
2. What is the main function of Leydig cells in the male reproductive system?
The primary function of Leydig cells is the synthesis and secretion of male sex hormones called androgens, with testosterone being the most important one. This hormonal production is crucial for spermatogenesis (sperm production) and the development of male secondary sexual characteristics.
3. Which hormone stimulates Leydig cells, and how is their function regulated?
Leydig cells are stimulated by the Luteinizing Hormone (LH), which is secreted by the anterior pituitary gland. Their function is regulated by a negative feedback loop. When testosterone levels are high, it signals the hypothalamus and pituitary gland to reduce the secretion of GnRH and LH, respectively, thereby decreasing testosterone production and maintaining hormonal balance.
4. What are the key histological features of a Leydig cell?
Under a microscope, Leydig cells are typically large, polygonal-shaped cells with a prominent nucleus. Their cytoplasm is characteristically eosinophilic (stains pink) and appears granular due to an abundance of smooth endoplasmic reticulum (SER) and mitochondria, which are cellular organelles essential for producing steroid hormones like testosterone.
5. How do the functions of Leydig cells and Sertoli cells differ?
While both cells are vital for male fertility, they have distinct roles:
- Leydig Cells: Located outside the seminiferous tubules, they produce testosterone under the influence of LH. Their function is primarily hormonal.
- Sertoli Cells: Located inside the seminiferous tubules, they provide nourishment to developing sperm, form the blood-testis barrier, and are influenced by FSH. Their function is primarily supportive and structural.
6. Why are Leydig cells so significant for male development and fertility?
The testosterone produced by Leydig cells is fundamental for male life. Its significance includes:
- Embryonic Development: Directing the formation of male reproductive organs.
- Puberty: Triggering the development of secondary sexual traits like a deeper voice, muscle growth, and body hair.
- Adulthood: Maintaining libido, bone density, muscle mass, and supporting the continuous process of spermatogenesis.
7. Do females have Leydig cells?
No, females do not have Leydig cells, as these are exclusive to the male testes. The analogous cells in the female ovaries are the theca cells. Similar to Leydig cells, theca cells are stimulated by LH to produce androgens, which are then converted into estrogens by the nearby granulosa cells.
