Bernhard Zondek 680 



hypophysectomized rats. Plate i, figure 2, shows an ovum tousisiing of five seg- 

 ments in a follicle of a rat (forty-seven days old, hypophysectomized twenty 

 days earlier). Cell no. 1 contains a nucleus, cell no. 2 a nuclear spindle; in cell 

 no. 3 only a suggestion of the small nucleus is recognizable in the photograph; 

 cell no. 4 contains no nucleus; cell no. 5 shows cytolysis. Plate 1, figure 3, shows 

 three segments of the ovum in a follicle of medium size of an infantile hy- 

 pophysectomized rat. Two of the segments contain nuclear spindles, the third a 

 polyaster. This may possibly indicate that subdivision has taken place. In the 

 segments, vacuoles are clearly seen, as a sign of the early stages of degeneration. 

 Ovular segmentation is, therefore, not a consequence of follicular atresia 

 since it occurs in the ripening as well as in the rupturing follicle. We are 

 inclined to assume that this phenomenon must be considered a degeneration 

 on parthenogenetic lines. The ovum which very early (even in the infantile 

 ovary) displays its ripening tendency may continue its development even with- 

 out fertilization. This parthogenetic impulse ends in an abortive effect, since 

 very soon degeneration sets in and the ovum dies with signs of cytolysis. The 

 constructive process is, therefore, very soon replaced by a degenerative one. 



Theory of Cyclic Menstruation 



In the foregoing we have seen that the ovum leads its own life in the ovary 

 and is of no significance to the cyclic process and the initiation of menstrua- 

 tion. In the following lines a brief account will be given of how the cycle and 

 the appearance of menstruation can be imagined to be brought about:'" Men- 

 struation is a complex process initiated by the functional, harmonious coop- 

 eration of the anterior lobe of the pituitary gland on the one hand, and ovarian 

 hormones and uterine mucosa on the other. The regulating factor of the en- 

 tire cycle is the estrogenic hormone— the estrogenic hormone level operating 

 similarly to the mercury level in the regulator of the thermostat. 



The cycle can be imagined to run as follows: In the theca cells, constantly 

 increasing amounts of estrogenic hormone are elaborated, the peak produc- 

 tion being in the middle of the cycle. The high estrone level cuts off prolan A 

 and this initiates the activity of prolan B. This hormone brings about follicular 

 rupture, corpus luteum formation, and progesterone production. Since now. 

 however, prolan A is no longer active, the estrone level is lowered, and this 

 lowering starts again the activity of prolan A, so that estrogenic hormone is 

 again produced. At the peak of production, that is, when the corpus luteum 

 is fully developed, the very high estrone level cuts off both gonadotrophic 

 factors (A and B) in the anterior pituitary. The gonadotrophic hormone can 

 no longer enter the blood stream, and in this way both progesterone and es- 

 terone levels are lowered. Some days later the bleeding sets in. With the lower- 

 ing of the estrone level, prolan A automatically comes again into activity, 

 previous to and during the hemorrhage, and the cycle of follicular maturation 

 is again begun. In brief: (1) lowering of the estrogenic hormone level brings 

 prolan A into activity, (2) high estrogenic hormone level cuts off prolan A, 



