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(From the Huxley Research Laboratory, Royal College of Science, London. ^ 



Some Points in the Spermatogenesis of Mammalia 



by 

 J. E. S. M r e , A. R. C. S. 



(With plates VII a. VIII.) 



Introductory. 

 It is now customary to regard the testicular cells of mammals 

 as consisting* of two quite distinct types, each performing its allotted 

 role in spermatogenesis independently of the other. In the adult 

 organ these two types are represented by the foot-cells, (supporting- 

 cells, giant-cells, cells of Sertoli) on the one hand, and by the senieni- 

 ferous elements, (or those which are either themselves directly, or 

 through their descendants indirectly, converted into spermatozoa), on 

 the other. The differentiation of these two kinds of cells from the 

 elements of the undifferentiated genital ridge is believed to occur 

 comparatively early during embryonic development, it is presumably one 

 of the first of the changes through which these cells pass while en 

 route towards the formation of the adult organ. However this may 

 be, it is by no means easy to find any adequate authority for tlie 

 belief; in fact, it seems to rest at present almost entirely on its own 

 inherent probability, and on the apparent analogy which certain in- 

 vertebrate spermatogeneses appear to offer notably those described by 

 La Villette St. George, who showed that the mulberry-shaped masses 

 in the spermatocytes, in tyjies like Blatta, arose from a single cell 

 the undivided moiety of which remaining behind as an undifferen- 

 tiated "cyst -cell". From these facts it is not unnatural to conclude 



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