456 THE HUMAN EMBRYO. 



luteum spurium, as it is then called, increases slightly in size for 

 a few days ; but ten or twelve days after the discharge of the 

 ovum, commences to shrink, and disappears completely in a few 

 weeks' time. 



If, however, the ovum that has escaped from the follicle is- 

 fertilised, and gives rise to an embryo, the corpus luteum. now 

 spoken of as corpus luteum verum, or corpus luteum of pregnancy, 

 does not reach its full development until two or three months 

 after the discharge of the ovum. It persists throughout the greater 

 part, or the whole, of pregnancy, contracting towards the close of 

 the period to a small white stellate cicatrix, the corpus albicans, 

 which may persist for some months after delivery. 



The fully developed corpus luteum verum, or corpus luteum 

 of pregnancy, is a firm body, larger than the original follicle, 

 and attaining one-fourth, or even one-third, the size of the 

 entire ovary (Fig. 255). 



The presence of a corpus luteum verum in one of the ovaries 

 is a matter of considerable medico-legal importance, inasmuch 

 as it has been appealed to as positive evidence of pregnancy 

 having occurred ; but the best authorities now agree that there 

 is no infallible sign by which the corpus luteum of pregnancy 

 can be distinguished from that of the non-fertilised ovum. The 

 differences between the two are chiefly those of size, and length 

 of duration, and cannot always be relied on in determining 

 disputed cases. The terms ' true ' and ' false,' as applied to the 

 two kinds of corpora lutea, appear, indeed, to be erroneous ; as 

 the two structures are essentially similar, and in many cases 

 indistinguishable from each other. 



3. Ovulation. 



From the time of puberty, and throughout the whole of the 

 child-bearing period of life, i.e. from about the fifteenth to about 

 the forty-fifth year, the gradual maturation of the Graafian 

 follicles, ending in rupture of the follicles and discharge of the 

 ova, is continually going on ; and in the healthy condition this 

 discharge of ova occurs, not in an indefinite manner, but at 

 regular, and usually monthly intervals, one or more ova being 

 set free at each period. 



This periodical maturation and discharge of ova is spoken of 

 as ovulation. It goes 011 independently of sexual intercourse. 



