CORPUS LUTEUM IN OVARY OF THE CHICKEN 6 



from a number of other Ijirds was used in the study of special 

 points. These are some of the same birds used in Study IX. 

 The ovaries were fixed in Gilson and McC'lendon. In the 

 Barred Plymouth Rock ovary the different discharged follicles 

 were sectioned separately and arranged in a series, according 

 to size and consequent order of age since ovulation. After the 

 study of this series, it was easy to judge of the condition of 

 various follicles in pieces of the other ovaries cut at random. 

 Various stains were tried, iron haematoxylin and Delafield's 

 haematoxyhn for general histology and Mallory's and Mann's 

 stains for secretion granule tests. 



II. UNDISCHARGED FOLLICLES OF THE HEN'S OVARY 



A study of the follicles of large undischarged oocytes shows 

 them to consist of an epithelial layer, the granulosa, and two 

 connective tissue layers, the inner and the outer theca folliculi 

 (fig. 1). In the inner theca are located groups or nests of epi- 

 thehal cells {I, figs. 1 and 2). They have been described by 

 many authors, notably Ganfini, Sonnenbrodt and Poll, but 

 have been called interstitial cells. Poll calls them Kornzellen 

 at first, describes their collection into the internal theca and 

 then implies their function by saying that the biological role 

 of the theca interna in the formation of the corpus luteum still 

 needs to be worked out. That he also confuses them with 

 interstitial cells is shown by his statement that the theca interna 

 fills up the atretic follicle with groups of Kornzellen, which is 

 the same thing as an interstitial gland. These nests of cells in 

 the bird are not anything like the usual glandular interstitial 

 cells of the ovary in structure. They are about three times 

 as large (compare fig. A and C). The nucleus is bigger and 

 plumper, the cytoplasm is usually clear and vacuolated in ap- 

 pearance, only occasionally containing a few acidophile gran- 

 ules which stain with the fuchsin in Mallory's stain or the eosin 

 in Mann's stain; while the real interstitial cells are crowded 

 with granules. These large clear cells are seldom found alone, 

 but are usually grouped into nests of various shapes, as already 

 mentioned. The cytoplasm of these cells usually will not take 



