468 



PHYSIOLOGY OF GONADS 



irf^'t'H-'^ 



. 7.'.). Aii< ^lioii.-. ral)l)U. J^aigc lulliclf^ lUulcifioinK ati< Ma Iiilcr^l il luui i,> \i>ilil<- only 

 as the narrow wedge of granular tissue extending from the cortex into the intrafollit-u- 

 lar septum. (Courtesy of Dr. J. T. Bradbiuy.) 



and can (ledift'erentiate to form connective 

 tissue cells (Esaki, 1928; Williams, 1950). 

 The role of Leydig cells as secretors of 

 testicular androgen or a precursor is not 

 (juestioned. In the ovary it is also presumed 

 that undifferentiated connective tissue ele- 

 ments exist, indeed much of the stroma must 

 be composed of such cells. It is believed 

 rather generally, although unequivocal proof 

 has not been given, that the theca interna is 

 derived from connective tissue elements and 

 that, as a component of the Graafian follicle, 

 it secretes estrogen and possibly androgen 

 Hoc. cit.). After ovulation and corpus lu- 

 teura formation, and after atresia in the case 

 of follicles not rui)turing, the cells of the 

 theca interna may pcrhajjs I'csuinc their 

 place as connective tissue cells or they may 

 become interstitial cells (Mossman, 1937; 

 Dawson and McCabe, 1955; Rennels, 1951 ; 

 Nishizuka, 1954; Williams, 1956). The 

 |)rominence of interstitial tissue varies from 

 species to species and also with stages of the 



rei)roductive cycle. Whether it is functional 

 in i^roducing hormones has been controver- 

 sial, but most contemporary investigators 

 seem to feel that internal secretory capacity 

 has been demonstrated. In all the work that 

 has been done, supporting evidence is var- 

 ied; in some cases it is circumstantial, but in 

 others it is quite substantial. 



Interstitial tissue is deficient in the anes- 

 trous rabbit, and even though there may be 

 considerable follicular development, there 

 seems to be little or no estrogen production 

 (Claesson and Hillarp, 1947a) (Fig. 7.9).^ 

 The liypei'ti'opliied iiitei'stitium of the es- 

 troiis i;il)l)it (Fig. 7.10) undergoes further 

 de\-el()pnicnt (hii'ing prc'gnancy and seems 

 almost as luteinized as th(^ corpora lutea 



' Rogr('ssi\-e changes in tlic rciirodiictixe tract 

 and accessory structures following ovariectomy of 

 the anestrous opossimi were taken to indicate that 

 these parts receive estrogenic stimidation of ovar- 

 ian origin during th(^ anestnun (Morgan, 1946; 

 Risman. 1946). 



