BY F. P. SANDES. 370 



long axis of the nucleus radially placed. This swelling of the 

 cytoplasm pushes the more centrally placed cells inwards, so that 

 tliey encroach upon the central cavity with its connective tissue 

 trabeculfe, and insinuate themselves between these trabeculse. 

 This cellular change is of the nature of an hypertrophy. No 

 multiplication of the cell nuclei by direct or indirect division can 

 bo made out, though carefully and often searched for in sections 

 treated with different stains. 



To sum up, the early corpus luteum is formed from the ruptured 

 follicle by two processes; first, an invasion of the ca^dty of the 

 follicle by vascular connective tissue sprouts of the theca folliculi, 

 it being impossible to distinguish between the part played by the 

 theca externa and the rudimentary theca interna; and secondly, 

 by an hypertrophy of the cells of the membrana granulosa. 



The Later Development of the Corpus Luteum. 



For the study of the later development of the corpus luteum, 

 serial sections w^ere made of ovaries corresponding to the stages 

 of ovum and embryo represented by closed blastodermic vesicles 

 up to the time of the formation of the primitive streak and head 

 process of the early embr3^o, that is the Stages E, F, F^, G and H, 

 previously described. The last of these stages of the embryo is 

 reached probably about the third day, though this point has not 

 yet been accurately determined, and represents approximately 

 the time when the formation of the corpus luteum is complete. 



The formation of the corpus luteum is carried on along the 

 lines already described. It has been shown how the connective 

 tissue invades the ca^■ity in the interior of the ruptured follicle. 

 The chief feature of the connective tissue during the later develop- 

 ment of the corpus luteum is the formation in connection with it 

 of blood vessels, so that the interior of the young corpus luteum 

 becomes filled with an angiomatous structure formed by branch- 

 ing blood vessels whose walls are composed of a single layer of 

 flattened endothelial cells. These vessels exist under usual 

 circumstances for some time previously to the filling of the spaces 



