Binding of 125I-HCG by rat testis homogenates in early neonatal period.

The binding of 125I-HCG by rat testis homogenates in early neonatal period was studied. The specificity of this binding was demonstrated by competition of unlabeled HCG and LH for binding sites and by failure of such binding to occur in specimens obtained from control tissues. FSH and ACTH were not able to compete significantly for 125I-HCG binding. The HCG-LH receptor is present in the testis during the whole postnatal period. The uptake of 125I-HCG by the testis of young rat does not differ during first two weeks of life and the rise of binding occurs at about the third postnatal week.