682 Ovum, Cycle, and Menstruation 



tion of the ovum after fertilization. Nevertheless, the anterior pituitary is the 

 superior factor in this process. Without the anterior lobe, without gonado- 

 trophic hormone, no follicular rupture would be possible, and the ovum could 

 not migrate through the tube to fulfill its natural function, fertilization. The 

 ovum itself, therefore, is of no significance for the process of hormonal pro- 

 duction in the ovary nor for the growth and breakdown of the uterine mucosa. 

 It has no bearing on cyclic changes. 



Segmentation of Ovum 



Although this problem is not directly related to the menstrual cycle, we are 

 taking the opportunity of referring briefly to our experiments concerning the 

 segmentation of the ovum. The subject usually employed for the study of this 

 phenomenon is the pregnant animal, since in its ovary follicular atresia is 

 particularly marked, and segmented ova are preponderantly met with in 

 atresic follicles. Spuler^'' holds the view that, in the degenerated granulosa 

 cells, substances may be formed which induce segmentation in the ovum. 

 L. Loeb"'^^ holds changed chemical and inechanical conditions in the atresic 

 follicle responsible for this event, while Haggstrom" takes changed osmotic 

 pressure or difficult supply of nutritional factors to the follicle into considera- 

 tion. Is segmentation actually nothing but the consequence of follicular atre- 

 sia? In order to study this question (ref. 7, p. 329) it was necessary to produce 

 artificial follicular maturation in the rat by means of prolan injections, in 

 order to find out whether in these ripening follicles segmentation might also 

 be discovered. A total of eighteen infantile rats were treated with prolan, and 

 serial sections of their ovaries were examined microscopically. In thirteen of 

 the animals segmented ova were in fact encountered. It seems to me note- 

 worthy that these segmented ova were present not only in atresic follicles but 

 also in the ripening ones as well as in those that had already reached the stage 

 of vascularization and, in part, luteinization. In one rat which had been treated 

 with prolan a segmented ovum was found on its way through one of the tubes 

 after follicular rupture (pi. 1, fig. 1). This tubal ovum consisted of five segments 

 of different size containing altogether ten chromatic bodies. Some granulosa 

 cells were still adhering to the ovum. It may thus be assumed that segmentation 

 is not a consequence of atresia. 



Is the segmentation of the ovum to be considered a regressive process? We 

 do not think that this is the case. Two separate processes have to be taken into 

 account: (a) Since the ovum shows signs of maturation, and, moreover, seg- 

 ments of equal size with perfect nuclei and mitoses are present, a mitotic divi- 

 sion of the ovum must be assumed; (b) even more frequently than this division 

 another picture presents itself which, in our opinion, is due to the chromo- 

 somes being drawn apart and secondarily enveloped in plasma so that seg- 

 ments with irregularly distributed chromatic bodies are formed. 



That segmentation of the ovum does not depend on the anterior hypophysis 

 is shown by the fact that a similar occurrence is also met with in infantile 



