180 GEORGE W. CORNER 



CONCLUSIONS 



1. In swine the membrana granulosa is retained intact after 

 the rupture of the Graafian follicle. Its cells increase in size 

 without division, their cytoplasm becomes laden with lipoid 

 substances, and they become the larger elements commonly 

 called 'lutein cells' in the fully formed corpus luteum. 



2. The membrana granulosa is invaded by blood-capillaries 

 from the theca interna, which ramify to form an extensive vas- 

 cular plexus throughout the new structure. 



3. The large lipoid-laden cells of the theca interna are increased 

 in number by mitotic division, lose many or all of their fatty 

 inclusions, and pass into the corpus luteum to become lodged 

 between the granulosa cells throughout the whole structure. 



4. There is no evidence that cells of the theca interna are ever 

 converted into fibroblasts of the usual spindle-cell type or that 

 they lay down the fibrils of the close-meshed reticulum which is 

 present in the corpus luteum. 



5. There appears to be good evidence that some of the theca 

 interna cells persist throughout pregnancy as distinct elements of 

 the corpus luteum, but the exact fate of all of them cannot be 

 learned by present methods because of a confusing resemblance 

 between some of the theca and some of the granulosa derivatives. 



BIBLIOGRAPHY 



Assheton, R. 1899 The development of the pig during the first ten days. 



Quarterly Journal of Microscopical Science, vol. 41, p. 329. 

 von Baer, K. E. 1827 De ovi mammalium et hominis genesi. Leipzig. 



Quoted by Bischoff ('42). 

 Barry, M. 1839 Researches in embryology. Philosophical Transactions of 



the Royal Society of London, 1839, pt. 2, p. 307. 

 Benckiser, A. 1884 Zur Entwickelungsgeschichte des Corpus luteum. Arch. 



f. Gyn., Bd. 23, S. 350. 

 IIischoff, Th. L. \Y. 1842 Entwickelungsgeschichte des Kaninchen-Eies. 



Braunschweig. 



1878 Uber die Zeichcn dor Rcife dcr Saugethicreier. Arch. f. Ann I. 



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 Bonnet, R. 1891 Grundrissder Entwickelungsgeschichte der Haussaugcthicre 



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