THE MENSTRUAL CYCLE 353 



4. Stage of Repair. — Lasting about seven days, this stage 

 consists iu a regeneration of the mucosa, contraction of 

 blood-vessels and reabsorption of blood which has not 

 been discharged. 



It is clear from what has been said above that the 

 menstrual cycle is but a form of the oestrous cycle. We 

 may thus synchronise the process as it occurs in women 

 with the general type appertaining to all mammals. 



Stage of Quiescence Anoestrum. 



Constructive Stage \ ppn-oestrum 



Destructive Stage {Menstruation) J 



Stage of Repair | Metoestrum 



In civihsed mankind oestrus has practically disappeared, 

 but it still persists in primitive races. 



The significance of menstruation and its correlation 

 with the changes which occur in the ovary will be discussed 

 later. 



The Ovary 



The ovary consists of a stroma of fibrous tissue with 

 unstriped muscle-fibres and blood-vessels. It is covered 

 by a single layer of epithehal cells — the germinal epithe- 

 lium. Lying in the stroma are a large number of vesicles 

 of varying size — these are the Graafian follicles in different 

 stages of development. Each follicle contains an ovum. 

 There occur also the corpora lutea, or discharged follicles. 



Ovulation and Maturation 



During sexual hfe the ovary undergoes a cycle of changes 

 concurrent with those occurring in the uterus. Those 

 consist in the hypertrophy of one or more folHcles. At 

 an early stage the folhcle consists of the ovum surrounded 

 by a single layer of epithehal cells. Immediately around 

 it the stroma is condensed to form a sheath. The growth 

 23 



