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Leydig's interstitial cells and hormonal regulation

Between the seminal canals lie Leydig's interstitial cells. These are endocrine cells that mainly produce testosterone, the male sexual hormone, and release it into the blood and into the neighboring tissues. An initial active stage of these cells occurs during the embryonic development of the testis. Later in juvenile life, due to the influence of the LH (luteinizing hormone) secreted by the anterior hypophysis (pituitary gland), Leydig's interstitial cells enter a second, long lasting stage of activity. Together with the hormones secreted by the adrenal cortex, testosterone initiates puberty and thus the maturation of the sperm cells.

Fig. 17 - Leydig's interstitial cells

  1. Leydig's interstitial cells
  2. Crystalloids of Reinke

Fig. 17

Group of large cells in the interstice between tubules. Leydig's interstitial cells characteristically contain large protein crystals (crystalloids of Reinke), the importance of which is unknown. The crystals are uncolored and stand out as light structures against the red cytoplasm of Leydig's interstitial cells.


Testosterone production is directed by LH (luteinizing hormone), secreted by the anterior lobe of the hypophysis. Pronounced cycles in hormone production, as are present in women, do not exist.
The second hormone secreted by the anterior hypophysis, FSH (follicle-stimulating hormone) affects Sertoli's cells, in that it triggers the formation of a testosterone-binding protein. Thereby testosterone can be transported by Sertoli's cells into the luminal compartment and there be concentrated. Testosterone is decisive for spermatogenesis.
Testosterone is also carried away via blood and lymph fluid. Testosterone has effects on all tissues, especially also on the brain during development as well as on the sexual organs.