Abstract
1) Pituitaries of 36 matur evirgin mice were examined to determine if there exist cyclic variations in the secretory cells of the anterior pituitary during the oestrous cycle.
2) The "peculiar chromophobe cells" were frequently found during proestrum and oestrum, while in metoestrum and dioestrum these cells fairly decreased in number.
3) The secretory cells, except for the "peculiar chromophobe cells," did not reveal any significant cyclic variations in percentages at different stages of the oestrous cycle. Qualitatively, on the other 26 Masao Sano hand, there were frequently found degranulated acidophiles during proestrum and oestrum, while in metoestrum and dioestrum acidophiles were well-packed with secretory granules in general.
4) From the present data and those of previous works at our laboratory, the author arrived at the conclusion that the " peculiar chromophobe cell " of the mouse anterior pituitary represents an independent cell type which differentiates from ordinary chromophobes. In addition, it can be assumed that the cells probably secrete a certain hormone which seems to regulate an ovarian function, although for the solution of the question as to which hormone is secreted by these cells further studies are required. The author designated these cells " theta. cells " following the terminology of Romeis.
