On the Corpus Luteum of the Rabbit.

8 Figures (Plate XVIII-XIX).One of the most interesting subjects in studying the ovaries is the changes occuring in the theca interna cells of the Graafian follicle in the time of the development of the corpus luteum after its rupture.As to this point, many divergence of opinions have been published, and still there is no comformity among the authors.Therefore, it is my purpose to investigate more thoroughly on the rabbit on the same question in addition to my previously published paper " On the Origin of the Corpus Luteum of the Mouse."As described in my previous work, the investigators thought that these cells are in different stages of development of the connective tissue cells, and their theories could be summarized as follows :-1.The theca interna cells of the mature follicle, not maximal differentiated, retain yet their nature of reverting into the original connective tissue cells again, and can form the connective tissue reticul um among the lutein cells with mitotic divisions.This opinion was maintained am-ong the authors of the granulosa origin theory of the corpus luteum such as, Sobotta in the mouse, the rabbit and the guinea-pig Meyer in man Iok a and Adac hi in the rabbit.Cohn explained that these cells can, furthermore, form the capillary blood vessels.2. The theca interna cells can never be reverted into the fibroblasts, but invade among the granulosa lutein cells without any changes.This contention is maintained by Solomon and Gat e n by in man, the pig and the duck-billed platypus.3. When the theca interna cells are multiplied by mitotic divisions after ovulation, and converted into the lutein cells with their gradual hypertrophy, contrary to the granulosa degeneration, then the theca interna origin theory will be asserted.This theory was proved by Buehler in man Clark also Doering in the pig; Jankowski in