The production of @entity251 in the adult testis is mainly regulated by LH. @entity251 is essential for normal development of the male fetus. The regulation of @entity251 production in the fetal testis is less clear than in the adult testis, and there are indications that at least the onset of @entity342 production in the fetal testis takes place in an LH-independent way. The aim of the present study was to compare the onset of synthesis and pattern of expression of LH receptors and two important steroidogenic enzymes, @entity1816 dehydrogenase (3beta-HSD) and 17alpha-hydroxylase/17,20-lyase ( @entity31018 ), in fetal @entity35 gonads. Whole fetuses (13.5 and 14.0 postcoitum (p.c.), testes, and ovaries dissected from fetuses on Days 14.5 p.c. to 20.5 p.c. and testes obtained on Days 3, 5, and 7 postpartum were fixed in Bouin's solution and processed for immunocytochemistry. In all samples of fetal testis, 3beta-HSD was detected on Day 14.5 p.c., and immunoexpression of @entity31018 appeared one day later on Day 15.5 p.c. Thereafter, immunoexpression of both enzymes remained intense throughout gestation and postnatally. In contrast, immunoexpression of LH receptors was detectable only from Day 16.5, when a few weakly positive cells were present, but it became more intense one and two days later. Similar to the immunostaining for 3beta-HSD and @entity31018 , immunostaining for @entity7813 remained strong throughout gestation and during the first 7 days of postnatal life. No immunoexpression of any of the three proteins studied was detected in the fetal ovary at any age. These data show very early immunoexpression of 3beta-HSD, which was detected one day before the reported start of @entity134 production by the fetal Leydig cells. In contrast, immunoexpression of LH receptors was evident only after immunoexpression of both the steroidogenic enzymes studied had became apparent and after the reported start of steroidogenesis, which is consistent with the theory that onset of steroidogenesis in the fetal @entity35 testis is an LH-independent process.

Immunoexpression of the steroidogenic enzymes 3-beta hydroxysteroid dehydrogenase and 17 alpha-hydroxylase, C17,20 lyase and the receptor for luteinizing hormone (LH) in the fetal XXXX testis suggests that the onset of Leydig cell steroid production is independent of LH action.

@entity251 :: ('MESH:D013739', 'Chemical') :: ['testosterone', 'Testosterone'] @entity1816 :: ('CHEBI:36836', 'Chemical') :: ['3beta-hydroxysteroid'] @entity7813 :: ('25477(Tax:10116)', 'Gene') :: ['LH receptor'] @entity134 :: ('CHEBI:35341', 'Chemical') :: ['steroid'] @entity342 :: ('CHEBI:50113', 'Chemical') :: ['androgen'] @entity31018 :: ('25146(Tax:10116)', 'Gene') :: ['P450c17'] @entity35 :: ('10116', 'Species') :: ['rat']
@entity35 :: (10116,Species) :: ['rat']
