Gonadotropic Hormones in the Hereditary Dwarf Mouse

Snell 1 described dwarfism in the mouse which was inherited as a recessive character. Smith and MacDowell 2 later showed that, in these mice, the eosinophiles were missing from the anterior lobe of the pituitary and that the growth hormone was either not present at all, or else was produced in amounts much less than in the normal. Transplantation experiments 3 were interpreted as indicating that pituitaries of the dwarfs contained a higher concentration of gonadotropic hormone than the normal. Nevertheless, sexual development was markedly retarded in both male and female, copulation and reproduction being impossible unless normal pituitary lobe was supplied by implantation or injection. Thus, it was difficult to understand why the gonadotropic hormone of the dwarf did not give the proper stimulus to its own gonads and accessory sex glands unless a synergistic action of the growth hormone was involved. These experiments were performed with relatively young mice and another interpretation seems possible from observations on older dwarfs which are to be described below.

Heterozygous parents were obtained from Snell in 1933 and dwarfs bred from these. In addition 2 dwarf males and 6 dwarf females were obtained from MacDowell in 1936. In all of 6 males observed after they had reached an age of a year or more priapism had developed. One such animal was given 2 injections of a Suspension of beef anterior lobe at 2-day intervals and the priapism disappeared within a week after the first injection. In 2 animals which were kept untreated for 17 months, the priapism was maintained constantly for the last 6 months. These untreated dwarfs were then sacrificed and were found to have very strikingly enlarged seminal vesicles. Microscopic examination showed that the enlargement was due to retained secretion.