584 



PHYSIOLOGY OF GONADS 



Repair 



Fig. 9.23. A diagram indicating correlated changes in ovary and endometrium during 

 an ovulatory cycle of rhesus monkey. Thickness of endometrium, density of stroma, gland 

 form, and three types of arteries are indicated. There is a gradual rise in thickness up to the 

 time of ovulation, and a brief decline followed by development of the luteal or progesta- 

 tional phase with accumulation of secretion in the glands due to relaxation of the 

 myometrium. This is followed by loss of ground substance from the stroma, which is the 

 primary factor in the premenstrual regression of the ischemic phase. This is a prelude to 

 extravasation and shedding of tissue. Incidentally, secretion is extruded and glands col- 

 lapse. There is further regression throughout the phase of menstruation. More than the 

 basal zone (coarse stipple) survives menstruation. During repair, thickening of the endo- 

 metrium is associated with increase in ground substance in the stroma and growth in the 

 glands. (From G. W. Bartelmez, 1957, Am. J. Obst. & Gynec, 74, 931-955, 1957, with 

 some modification of description.) 



flow, and is associated with leukocytosis in 

 the endometrium. (4) The portion of the 

 coiled arteries located adjacent to the mus- 

 cularis constricts 4 to 24 hours before the 

 onset of the flow. This vasoconstriction per- 

 sists throughout the menstrual period ex- 

 cept when individual coiled arteries relax 

 and blood circulates through them for a few 

 minutes. Markee postulated that the im- 

 mediate cause of menstruation under these 

 conditions was the injurious effect of anox- 

 emia upon the tissues of the endometrium 

 l)rought about by mechanical compression 

 and constriction of the coiled arteries. 

 Therefore, the coiled arteries and their mod- 

 ifications become the central feature upon 

 which the theory is based. 



Although this offers an explanation for 

 many of the facts, it falls short in that now 

 it is known that menstruation can occur in 

 the absence of coiled arteries. Kaiser (1947) 

 showed that no spiral arteries are present in 



the endometrium of three species of South 

 American monkeys known to menstruate. 

 He also found that the coiled vessels of the 

 endometrium could be destroyed almost 

 completely by giving large doses of estrogen 

 and yet bleeding followed estrogen with- 

 drawal. 



Several experimental conditions under 

 which the coiled vessels of the endometrium 

 are destroyed have been mentioned in the 

 present discussion and in each instance 

 bleeding invariably followed withdrawal of 

 the supporting stimulus. The extremely 

 atrophic endometrium present at the conclu- 

 sion of a prolonged treatment with proges- 

 terone (Fig. 9.8) will bleed when the 

 injections are stopped, and if estrogen in- 

 jections are started immediately thereafter 

 the endometrium that develops is normal 

 with the exception of the absence of coiled 

 arteries; even so, it also will bleed when 

 the treatment is stopped. Even a more 



