Summary. The interaction of 125I-labelled hFSH with primate testicular tissue from 4 species of adult monkeys (Macaca mulatta, M. nemestrina, M. fascicularis and Papio cynocephalus) was investigated. 125I-labelled hFSH binding to a particulate fraction (P1, 40 000 g) of frozen testes was highly specific and saturable. Displacement curves generated using the P1 fraction of testes from the 4 species and 125 I-labelled hFSH and unlabelled FSH were very similar. The binding of FSH to the monkey testicular receptor was not species specific because purified FSH from heterologous species such as horse, sheep, pig and rat were very effective in competing with 125I-labelled hFSH for binding. The equine FSH was about 10 times more active than hFSH in this respect. Similarly, 125I-labelled ovine FSH bound as well as labelled hFSH to the testes fractions of all 4 monkey species. In marked contrast to the high binding of 125I-labelled hFSH, binding of 125I-labelled hCG with rhesus monkey testis homogenates and P1 fractions was very low. The FSH receptor in the adult rhesus monkey testis was present in much larger quantity than the LH receptor and was more readily detectable. Our studies show that frozen primate testis can be utilized for investigating testicular– FSH interactions.
M. I. Berman and M. R. Sairam
H. G. MADHWA RAJ, M. R. SAIRAM and N. R. MOUDGAL
The use of specific anti-fsh and anti-lh substances has shown that lh is the only pituitary gonadotrophin involved in the implantation process. Using different dosages of lh antiserum at different time intervals, it has been possible to arrive at a minimum effective dose (0·05 ml) which, when given on the 4th day at 10.00 hours, results in inhibition of implantation on the 8th day. We have shown that, at this dose, the antiserum is mainly inhibiting the oestrogen surge. It is proposed that an lh surge precedes an oestrogen surge on Day 4 of pregnancy.