244 MICROSCOPIC ANATOMY OF THE ORGAXS. 



licular epithelium making up the membrana granulosa i. e., 

 from the epithelium. There are many adherents to each of 

 these views, but the balance of evidence seems to be in favor 

 of v. Baer's theory. Other theories have been advanced, but 

 have gradually been abandoned. J. G. Clark has studied 

 the subject, and believes that the lutein cells are specialized 

 connective-tissue cells derived from the theca interna. Accord- 

 ing to him, they appear in the inner layers of the follicle wall 

 when a differentiation into theca interna and externa is 

 beginning. 



Whatever the origin of the lutein cells may be, it is certain 

 that the corpus haemorrhagicum is invaded on all sides by large 

 yellow cells containing fatty granules (lutein) ; and that by this 

 invasion the blood-clot is replaced by a definite cellular tissue, 

 the whole making up the corpus luteum (Fig. 186). The lutein 

 cells give to the body a yellowish color, and often there are 

 found orange-red hsematoidin crystals, which are the remains 

 of the blood-clot. 



According to Clark, the lutein cells in the growing follicle 

 increase at the expense of the cells of the theca interna, and 

 there is also present a network of true reticulum stretching 

 from the theca externa among the lutein cells and collected into 

 a membrane next the tunica granulosa to form the membrana 

 propria folliculi. When the follicle ruptures, this membrane is 

 broken through by the growth of lutein cells and blood-vessels. 

 As soon as the corpus luteum has reached its highest develop- 

 ment, certain changes take place in the cells and the retro- 

 gression begins. Fatty degeneration in the lutein cells is fol- 

 lowed by an increase in the connective tissue. The septa 

 become thicker and all the connective tissue of the corpus 

 luteum shrinks to form a firm, compact body, which is known 

 as the corpus albicans or c.fibrosum. This becomes always 

 more contracted, like scar tissue, and finally undergoes hyaline 

 degeneration and is lost in the ovarian stroma. 



We distinguish corpora lutea vera and corpora lutea spuria 

 according to whether they arise from follicles whose eggs have 

 become fertilized or not. There is no difference in the intimate 



