CORPUS LUTEUM IN OVARY OF THE CHICKEN 7 



center (c) shows where the edges of the internal theca have drawn 

 together and obhterated the cavity. 



We have traced thus far the general histological changes 

 involved in the shrinking and lilling up of the discharged follicle. 

 We must consider next in more detail, the cytology of these par- 

 ticular cells involved. Figure 2 and figure A show them in 

 their original condition from a large undischarged follicle. We 

 have earlier in this paper pointed out their especial characteristics 

 in distinction to the interstitial cells. By the time they are 

 close enough together to cause the vacuolated appearance of the 

 whole inner part of the theca interna, the nuclei are somewhat 

 shrunken and pushed to the side of the cell, suggesting active 

 elaboration of secretion material (fig. 6 and fig. B). By the 

 time the closing in of the follicle has neared completion (figs. 

 8 and 9), the character of the cells is decidedly modified (fig. 

 C). The cell boundaries in any one small mass of cells are 

 indistinguishable. The cells seem to have melted together so 

 that the outlines of the vacuoles are the evidently visible lines 

 rather than the cell outlines. The vacuoles also are much 

 larger than previously. The nuclei are smaller and less regular 

 in outline, they stain darker, in fact, they look shrunken. These 

 figures show nicely the contrast between the cells which fill up 

 this discharged follicle and the interstitial cells. The interstitial 

 cells lie in the connective tissue of the external theca and of the 

 internal theca in between the masses of transformed epithelial 

 nest cells. They are entirely unchanged from their usual ap- 

 pearance. They show clearly because the granules with which 

 they are packed stain vividly with acid stains. A homologous 

 mass of cells from an older solidly filled follicle (fig. 10) is shown 

 in figure 11 and figure D. Here the nuclei show still further 

 signs of degeneration and the general network of the cytoplasm 

 contains clumps that look like secretion material. These secre- 

 tion particles are yellow in color. They look amorphous in 

 character, and they vary greatly in size (fig. 20). They can 

 not be fatty, for they have not dissolved in the clearing oils. 

 They cannot be of the protein nature of the secretion granules 

 of the interstitial cells, as they retain their distinct yellow color 



