Parthenogenetic Development of Eggs in the Ovary of the Guinea Pig

Abstract

In 1905 I described, 1 in the ovary of the guinea pig, unusual structures which at first I interpreted as peculiar types of follicular atresia. Further experience, however, convinced me that these structures originated from parthenogenetically developing ova. 2 Since then, long continued study of the ovary of the guinea pig and its various structures has strengthened my conviction that my interpretation was correct. 3 However, a paper by Kampmeier 4 recently expressed the opinion that the structures described by me are not embryonic in character but represent abnormal corpora lutea.

In view of the great interest in this question and because a fuller publication, for which I had begun to prepare several years ago, has to be delayed, and to prevent the acceptance of erroneous interpretations, I here state briefly the principal reasons which led me to the conclusion (a) that we have to deal in the ovarian structures with embryonic formations and (b) that these embryonic structures owe their origin to parthenogenesis.

(a) The conclusion that we have to deal with embryonic structures is based on the following facts: (1) in 2 animals I observed, within ovaries, early embryos corresponding approximately to the neurula, and in a third case, remains of such structures. One should expect that in the circumscribed area of an ovarian follicle the embryonic development would be very defective; yet, in one case the compression exerted by the rigid wall of the follicle led to only very slight abnormalities, while they were somewhat greater in the second animal. Not only embryonic structures like a neural tube could be readily recognized but, also, the trophoblast was well developed. In more than 30 guinea pigs, we found in the ovary structures closely corresponding to the fetal placenta.