[Quantitative histo-enzymological study of delta 5-3 beta-hydroxysteroid dehydrogenase activity in rat testis during the perinatal period. Relation with testicular crisis in the newborn rat].

The purpose of the present work was to determine if the neonatal testosterone surge in the rat (between 0 and 6 h after birth) was coincident with the histological and histochemical changes in the neonatal period. The histological study shows a decrease in the number of gonocytes and cells in mitosis. These observations are in good agreement with the results obtained by other authors. The critical period of birth does not reveal histological changes, between 0 and 6 h. By contrast, the histochemical analysis, based on the quantitative study of the delta 5-3 beta-hydroxysteroid deshydrogenase (key enzyme of the testosterone biosynthesis) demonstrated a regular enzymatic activity decreasing, from the foetal stage of 20.5 days to the birth, following a drastic increasing, from 0 to 2 h. The enzyme activity decreases gradually until 1 day after birth. The surge has been observed also if the foetus is removed by cesarean. These results demonstrated that the testicular crisis of the newborn Rat is simultaneous with an increased synthesis of testosterone in the testis.