222 INTERNAL SECRETIONS 



stroma of the ovary. Robert Meyer (1921) declared that there 

 are never nests of interstitial cells in the ovary of the non- 

 pregnant woman independently of the follicular tissue, and 

 that the "interstitial gland" is only a "phantasy" of some 

 authors. On the contrary, Seitz (1921) claims that it would be 

 "nonsense" to deny that the gland exists in the guinea pig or 

 in the rabbit, and that the interstitial gland is present also in 

 the woman. This tissue is absent or rudim.entary in the woman 

 only after she has attained maturity; it is then replaced by the 

 corpus luteum. 



The want of agreement between the statements of various 

 observers may be explained partly by the fact that whereas 

 some restrict the term interstitial "tissue" to cells which exist 

 outside the walls of the follicles, as in the rabbit, others denote 

 the mass of the atretic folHcles undergoing degeneration in the 

 ovaries of man and mammals as interstitial tissue, and identify 

 it with the parenchymatous tissue in the ovary of the rabbit. 

 It will be shown in the following section that the interstitial 

 tissue of the ovary, even when really present, as, for instance, 

 in the rabbit, is derived in general /row the follicle; the inter- 

 stitial cells originating from the cells of the stroma play quan- 

 titatively a very minor role. Further, interstitial tissue is not 

 necessarily the same as interstitial gland. There is no justifica- 

 tion for confounding a purely histological question with a 

 physiological one. The confusion which has arisen in regard 

 to this question is unfortunate. 



2. The Origin of the Interstitial Cells of the Ovary. 

 Limon (1901) was the first to undertake a full investigation 

 of this question. He stated in accordance with a suggestion of 

 former authors that the development of interstitial cells is 

 related to follicular obliteration, as seen especially in the rat 

 and in the rabbit (Figs. 102, 103). The formation of the inter- 

 stitial tissue begins in the rat soon after birth, whereas in the 

 rabbit it does not begin until an age of four months, or, as we 

 foimd, sometimes even later. The whole process begins with 

 the transformation of the irregular or spindle-shaped connective 

 cells of the theca interna, which become spherical and increase 

 in volume. Fat droplets appear in the protoplasm of the cells. 

 At the same time, a degeneration occurs in other cells of the 

 follicle, in the cells of the granulosa and in the ovum itself. 



