Morphologic and Quantitative Reaction of Ant. Pituitaries of Castrated Female Rats to Oestrin Injections. ∗

It is well established in the literature that castration in the female rat results in an increase in the basophiles and their development into castration cells. However, there is considerable disagreement concerning changes in the eosinophiles. In recent quantitative studies Ellison and Wolfe 1 reported that castration in the mature female rat resulted in an early increase in the size and the relative percentages of the basophiles in the anterior hypophysis which reached an apex approximately 30 days after castration (Table I). At this time a few signet-ring castration cells appeared. From the 30th day of castration there was an increase in the relative level of the castration cells, while the percentages of the basophiles decreased. There was also a moderate increase in the percentage of the eosinophiles in 30- and 60-day castrates (Table I).

It is equally well established that the injection of oestrin prevents the changes which ordinarily occur in the basophilic elements after castration. The experiments recorded below were carried out in order to obtain statistical data on the action of oestrin on the anterior lobes of female rats castrated for periods of 30 and 60 days.

Seventy-one mature female rats castrated for 30 days and 30 rats castrated for 60 days were used. Twenty-eight of the 30-day castrates received 25 units of oestrin† ‡ daily throughout the castration period while 12 of the 60-day castrates received similar injections for the last 30 days of the 60-day castration period. Vaginal smears were made throughout the injection period. Serial sections of the pituitaries were cut and cell counts made; their relative percentages were calculated and are presented statistically in Table I. For non-castrate control material previous studies on the pituitaries of 143 normal female rats were utilized.