It has been shown (Lane, '35 a ) that the ovaries of normal immature rats treated with purified follicle stimulating hormone (F.S.13.) possess a greater number of follicles than control ovaries from untreated rats of the same age. There is no clisturbaiice in the proportion of vesicular, that is, antrum-containing, follicles. The luteinizing hormone (L.H.) produces no increase in the total follicle content, but the percentage of vesicular follicles is increased approximately 50 per cent over the normal.
It also has been shown (Lane, '35 b) that injection of oestrin results in the production, by the pituitary, of increased amounts of luteinizing hormone or of something else, which acts in a similar way upon the ovary. The results of Wolfe ( ' 3 5 ) who injected oestrin into mature female rats and found that the corpora lutea were 'definitely and consistently larger' than controls, and that the cytology of the pituitaries was characteristically changed lends some confirmation to this con- ception of the action of oestrin.
The pituitary then, is definitely influenced by the functional activity of the ovary and can, in its turn, cause measurable changes in the follicular apparatus of the gonad. Faced with this very real possibility of vitiation of the ovarian results of Aided bp a grant from the National Research Counc4, Committee on Problems of Sex, administered by F. L. Hisaw.