title: Studies of the human testis. XI. Leydig cell clusters and levels of intratesticular testosterone and 20 alpha-dihydroprogesterone.
abstract: Testosterone concentration in testes of 23 men, ages 51 to 90, was determined as 490 +/- 172 ng/g tissue (M +/- S.D.) and 20 alpha-dihydroprogesterone concentration as 10.0 +/- 2.3 ng/g tissue (M +/- S.D.) in 18 men of the same patient group. Leydig cells were estimated by the number of Leydig cell clusters per tubule. There was a high correlation (r = 0.88, p less than .001) of the Leydig cell index with intratesticular testosterone. It is proposed that the Leydig cell cluster index provides a direct index of steroid biosynthetic activity in the human testis as reflected in intratesticular testosterone levels. Although there was no significant correlation of 20 alpha-dihydroprogesterone levels in the testis with either the Leydig cell index or intratesticular testosterone, the high level of 20 alpha-dihydroprogesterone compared to peripheral levels suggests its production by the testis.
mesh_terms: D004092:20-alpha-Dihydroprogesterone / Q000097:blood / Q000378:metabolism*; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000378:metabolism; D006801:Humans; D007985:Leydig Cells / Q000166:cytology*; D008297:Male; D008875:Middle Aged; D011374:Progesterone / Q000031:analogs & derivatives*; D011471:Prostatic Neoplasms / Q000378:metabolism; D013737:Testis / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism*
chemical_list: D004092:20-alpha-Dihydroprogesterone; D013739:Testosterone; D011374:Progesterone