64 INTERNAL SECRETIONS OF THE OVARY 



very greatly in different individuals. Subsequently, the 

 endometrium re-forms and returns to the resting stage. 



The uterine changes in monkeys, as described by Heape, 

 Corner, and other writers, are essentially similar. Heape 

 divided the whole cycle into eight stages: i. resting stage, 2. 

 growth of stroma, 3. increase of vessels, 4. breakdown of vessels, 

 5. formation of lacunae, 6. rupture of lacunae, 7. formation of 

 menstrual clot, 8. recuperation stage. Corner gives the following 

 description of the menstruating uterus of Macacus: ' In general 

 the menstrual process consists of an extravasation of blood in 

 the more superficial part of the endometrium. This leads to the 

 necrosis and collapse of the stroma and glands in the affected 

 region, and here and there to the lifting away of small sheets of 

 epithelium by formation of haematomata under them. It 

 appears that most of the surface is denuded of epithelium; that 

 portions of the glands may be lost, and that the stroma is 

 necrosed and cast off to a depth of roughly one-fourth of the 

 entire thickness of the endometrium. ... As far as can be made 

 out in these specimens regeneration of the epithelium is by 

 growth from the glands and perhaps from the undisturbed islets 

 of epithelium. The result is a smooth healing of the wound- 

 surface with a single layer of very low epithelium.' 



Information as to the time relations of the various phases of 

 the uterine cycle in monkeys does not seem to be available, 

 though the actual duration of menstruation (four to six days) is 

 similar to that of the human, as is the total length of cycle. 



The ovarian cycle. The difficulties in the way of obtaining 

 suitable human material of known history, together with the 

 untrustworthiness of the methods employed, led many of the 

 earlier workers, such as Steinhaus (597), Jackson (314), Leopold 

 (360) and Aveling (52), to doubt the existence of a regular 

 ovarian cycle in man. This conclusion was supported by the 

 erratic behaviour of the ovaries of Heape's monkeys. More 

 recent work, however, and our general knowledge of mammalian 

 reproduction, makes it necessary to suppose that a regular 

 ovarian cycle exists in the normal human, as in lower mammals. 

 In monkeys, on the other hand, under conditions of captivity in 

 temperate climates, the ovarian cycle very often appears to be 

 in abeyance. In both cases information as to the details of the 



