Effects of Methallibure (ICI 33,828) on the pars distalis of pituitary,testis and thumb pad of the green frog,Rana esculenta L.

Summary The influence of ICI compound 33,828 (1--methylallylthiocarbamoyl-2-methylthiocarbamoylhydrazine = Methallibure) on the pars distalis of pituitary, testes and thumb pads was investigated in the intact adult male green frog, Rana esculenta. Methallibure affected the gonadotropic basophils (particularly the B2 cells) of the pars distalis, which showed varying degrees of degranulation and underwent a notable decrease in their percentage. Within the testis this compound caused the arrest of spermatogenesis. The most uniform effect of Methallibure was observed in the thumb pads, which invariably showed regression of the epidermis and glandular epithelium. No histological changes occurred in the thyroid and adrenal glands and the B1 and A1 cells of the pars distalis remained unchanged cytologically. It is concluded, in concordance with the available data, that Methallibure is a non-steroidal antigonadotropic compound. The important question about its mode of action has been brought into discussion.Work supported by the National Research Council of Italy, and the Population Council (Grant No. M70.082 C) of New York.