Abstract
A fetal horse ovary at the 6th month of gestation and a fetal ovary and testis at the 9th month have been studied histochemically with special reference to the cytoplasmic lipids of the interstitial cells. At least two lipid fractions appeared to be present, one which was soluble in acetone and was mainly responsible for the positive "plasmal" reaction, and another, insoluble in acetone, which was responsible for the sudanophilic, Ashbel-Seligman and periodic acid-Schiff positive material remaining after acetone extraction. The interstitial cell lipids in the older ovary and testis were also autofluorescent both before and after acetone extraction. No birefringent material was noted in any of the specimens.
The tentative interpretation of the findings as indicative of possible sites of ketosteroid hormone synthesis or storage is discussed briefly and related to the problem of the hormonal interrelationships of mother and fetus in the horse.