On the Occurrence of the Oestrous Cycle after X-Ray Sterilisation. Part III.--The Periodicity of Oestrus after Sterilisation of the Adult

In Parts I and II (2, 3, 10, 11) of these series it has been shown that the destruction of the Graafian follicles in the young female mouse by exposure to X-rays does not inhibit the appearance of œstrous symptoms when the animals subsequently become mature. The conclusions arrived at were briefly as follows :— ( a ) After irradiation of the young animal the follicles disintegrate and are re-absorbed, this process being accompanied in its later stages by the proliferation of new tissue from the germinal epithelium. ( b ) When the animal becomes adult the ovary contains neither organised follicles nor corpora lutea vera, and consists largely of post-irradiation proliferation of the germinal epithelium. In spite of this, however, the cyclic phenomena of œstrus still appear.