400 INTERNAL SECRETION 



that structures genetically and morphologically analogous to the 

 interstitial gland of animals are present in man. Seitz does not, 

 however, believe that these cells possess an internal secretion. 



In later investigations, conducted with the utmost care, Wal- 

 lart found that more or less well-developed interstitial tissue was 

 invariably present in the human ovary when growing vesicles 

 were also present. Similar cells are observed in new-born infants, 

 but there are no fatty enclosures in the protoplasm of the elements 

 of the theca interna. These fatty enclosures are invariably present 

 in older individuals, except such as have died from serious ex- 

 hausting diseases. The interstitial tissue continues to increase up 

 to puberty and even until the end of the second decade, but its 

 development is most marked and the cell agglomerations are 

 thickest during the period between infancy and puberty. At a 

 later stage, the development of this tissue is less marked than that 

 of the other parts of the ovary. The interstitial gland attains its 

 highest development during pregnancy. In many cases of patho- 

 logical pregnancy (hydatid mole, chorionic epithelioma), the 

 maximal development is attained. During menstruation an en- 

 largement of the gland takes place which is reminiscent of the 

 conditions during pregnancy. At the climacteric, the gland ceases 

 to develop, and remnants only are found in the ovaries, though 

 these persist for some time. According to Wallart, the situation 

 which is most favourable to the conversion of the theca interna 

 into the interstitial gland, is the portion of the ovary immediately 

 below the cortex, and it is here that the atretic follicles chiefly 

 undergo development. 



Frankel was the first to assume a functional interrelationship 

 between the interstitial tissue and the corpus luteum ; he suggested 

 that the function of the corpus luteum might, under certain con- 

 ditions, be replaced by that of the tissue which is formed from 

 the atretic follicles. This assumption rests upon the presence of 

 a cell form, the lutein cell, which is apparently identical in both 

 tissues ; the theory is negatived, however, by the histogenetic 

 differentiation between the corpus luteum and the interstitial 

 gland a point upon which Seitz laid special emphasis. 



Seitz gave expression to his view in a new and eminently 

 appropriate form of nomenclature. He calls the lutein cells of 

 the interstitial tissue, which are formed from the theca interna, 

 theca lutein cells, in contradistinction to the granulosa lutein cells 

 of the corpus luteum, which, according to Sobotta's exact in- 

 vestigations with mice, are formed from the hypertrophic follicular 

 epithelium. 



From the results of very careful observation of human ovaries, 

 Cohn recently settled the vexed question of the origin of the lutein 

 cells. According to Cohn, the development of the corpus luteum 

 and that of the atretic follicles are two essentially different pro- 

 cesses. Histogenetically, the lutein cell is not homogeneous. 



