Morphological and functional development of the ovary of the mouse. I. Morphology and histochemistry of the developing ovary in normal conditions and after FSH treatment.

M A T U R A T I O N and maintenance of ovarian function are under the control of the pituitary gonadotrophins. The capacity of the ovary to respond to FSH stimulation develops gradually with age, and is most pronounced when the animal approaches sexual maturity. In very young animals reactivity to gonadotrophins is found to be lacking, and up to a certain age, which is characteristic for each species, sexual maturity cannot be accelerated by exogenous gonadotrophic stimulation (for references see Price & Ortize, 1944). However, in transplantation experiments of young ovarian tissue into adult spayed hosts, the grafted ovary reaches maturity much earlier than in its normal surroundings (Goodman, 1934; Dunham, Watts & Adair, 1941). In an attempt to clarify further the influence of the adult host on the development and maturation of the ovary, the normal growth of the mouse ovary and its reactivity to FSH from birth to maturity has been compared with the development of these young ovaries transplanted into adult hosts. In this first part, dealing with normal growth the correlation between differentiation of ovarian tissue and its sensitivity to FSH is considered; morphological observations of the developing ovary are supplemented by histochemical data which could be instrumental in revealing tissue-differentiation. In the second part of the investigation (in preparation) the development of the