452 ANATOMY FOR NURSES [Chap. XXI 



the age at which girls usually attain puberty is about foiuteen 

 years. In southern countries it is somewhat earlier, and in the 

 arctic regions, a year or two later. However, no fixed rule can be 

 given, as the time of arrival at puberty varies with every individual, 

 depending on race, temperament, hygiene, and general surround- 

 ings. 



The period preceding puberty, during which the physical changes 

 are occurring, is known as the period of adolescence. 



Ovulation. — Ovulation includes the process of the develop- 

 ment and maturation of the follicle and its ovum, and the rupture 

 of the follicle. 



The commonly accepted theory is that about or shortly before 

 the age of puberty the Graafian follicles begin to discharge their 

 ova, and that this process continues until the menopause. The 

 frequency with which well-developed ova are discharged is the 

 subject of much dispute. The most conservative view is that 

 there is one mature ovum discharged for each menstrual epoch, 

 probably some days before the period occurs. 



Menstruation. — Menstruation consists of the periodical discharge 

 of bloody fluid from the uterine cavity, "\^^len once established 

 it occurs on the average every twenty-eight days from the time of 

 puberty to the menopause, with the exception of the periods of 

 pregnancy and lactation. The average duration is from four to 

 five days and the amount of blood lost is about six ounces. The 

 menstrual fluid consists of mucus, epithelial cells, and blood. 

 Some authorities are of the opinion that the mucous membrane of 

 the uterus is normally shed during this process, others do not 

 share this opinion. 



The menopause or climacteric. — By menopause or climacteric is 

 meant the physiological cessation of the menstrual flow, and the 

 end of the period during which the Graafian follicles develop in 

 the ovaries, and consequently the end of the child-bearing period. 

 It is marked by atrophy of the breasts, uterus, tubes, and ovaries. 

 The age of menopause varies as does the age of puberty ; in general, 

 we may say the earlier the puberty the later the menopause, and 

 vice versa. In temperate climates the average period tor the arrival 

 of the menopause is at the age of forty-five years. 



Changes in the generative organs in connection with menstrua- 

 tion. — At the beginning of menstruation there is a general con- 



