ITS STRUCTURE AND DEVELOPMENT. 51 



on the subject, Paterson, Lee, Ritchie, Raciborski, Deschamps, and Renaud 

 maintain, at all events as regards the human female, that a true and fully 

 formed corpus luteum is met with only where an ovum has been impreg- 

 nated ; and, consequently, that such a body is a sure evidence of previous 

 impregnation. Most of these writers lay great stress on the distinction to 

 be drawn between true and false corpora lutea. 



In order the better to judge of the value and correctness of their views 

 it will be well in the first place to inquire what is the structure and mode 

 of growth of a corpus luteum formed during pregnancy in mammiferous 

 animals as well as in man. 



The corpus luteum of mammiferous animals when fully formed is a 

 roundish solid body, of a yellow or orange colour, and composed of a 

 number of lobules which surround, sometimes a small cavity, but more 

 frequently a small stellifonn mass of white substance ; the delicate pro- 

 cesses given off by this white mass passing as septa between the different 

 lobules of the yellow body. Very often in the cow and sheep, there is no 

 white substance in the centre of the corpus luteum ; and the lobules 

 projecting from the opposite walls of the Graafian follicle, appear in a 

 section to be separated by the thinnest possible lamina of semi-transparent 

 tissue. 



It is an important fact, that the development of the corpus luteum 

 commences before the rupture of the Graafian follicle. The follicle 

 which is about to burst and expel the ovum, becomes highly vascular and 

 also opaque ; and immediately * before the rupture takes place, its walls 

 appear thickened on their interior by a reddish, glutinous or fleshy sub- 

 stance. Immediately after the rupture the inner layer of the wall of 

 the follicle appears pulpy and flocculent. It is thrown into wrinkles by 

 the contraction of the outer layer, and soon red fleshy mammillary pro- 

 cesses grow from it, and gradually enlarge till they nearly fill the follicle, 

 and even protrude from the orifice in the external covering of the ovary. 

 Subsequently this orifice closes, but the fleshy growth within still increases 

 during the earlier period of pregnancy, the colour of the substance 

 gradually changing from red to yellow, and its consistence becoming 

 firmer. 



The corpus luteum of the human female differs from that of the do- 

 mestic quadruped, in being of a firmer texture and having more frequently 

 a persistent cavity at its centre, and in the stelliform cicatrix which remains 

 in the cases where the cavity is obliterated, being proportionally of much 

 larger bulk. 



The following are the more obvious phenomena of its formation:- 

 First, the Graafian follicle which is about to discharge its contents, be- 

 comes very vascular, then its walls lose their transparency and a very thin 



* The time, according to Bischoff's observation, (Entwickelungs-geschichte, p. 32,) must 

 be very short. 



