DEVELOPMENT OF THE LH-RESPONSE IN FETAL GUINEA-PIG TESTES

The influence of LH on testosterone secretion by testes from 25-30-day-old guinea pig fetuses cultured in vitro was investigated. Testosterone secretion by testes from 30-day-old fetuses could be stimulated by LH during the first 24 h in organ culture. Testosterone secretion by testes from 25-29-day-old fetuses could not be stimulated by LH during 5 days in organ culture. Development of testosterone and androstenedione synthesis by testes from fetuses of 25 days was observed during 5 days in organ culture. A stimulation of testosterone and androstenedione production by LH at that fetal age, however, could not be measured. Testosterone synthesis by fetal guinea pig testes explanted at 25 days could be stimulated by LH when they were precultured for 6 days. Similarly [125I]-hCG binding by gonads from fetuses of 25 days could be detected only after organ culture of these gonads for at least 6 days. These results indicate that in early guinea pig fetuses development of testosterone synthesis precedes the development of LH responsiveness.