THE HUMAN CELLS OF SERTOLI. 



live ultimate spermatogonia there is necessarily one to every 

 twenty-four spermatozoa; accord ingly. in man the number of 

 -permaio/oa, spermatic bundle, associated with one Sertoli cell 

 cannot be "8 or 16" as Bugnion states. 



But the point oi the greatest interest with regard to the dif- 

 ferentiation of the human Sertoli cell. i- thai it is determined by 

 the inclusion of a peculiar cytoplasmic rod, thi- rod tir-t .iri-inu 

 in the antepenultimate -pennatogonia. No such "Sertoli cell 

 determinant" ha- been made km>\\ n in any other object. In the 

 e of the dili n niiati-in of tin- oo-onia from the nur-e cell- in 

 the ovary <>i the beetle />v//.v</fv, SO \\ell de-cribed by ('liardina 

 r O] , and corroborateil by I >ebai-ieii\ '> i . there is a remarkable 

 met hani-m of differentiation of the nur-e cells: here the cell-; that 



are io become oocytes receive a cast-ofl n-ticular pan of the 



inn It ii-, \\hile the cell-, \\hich lack thi- extruded mass become 



nur-e cell- I \\ill be seen that thi- i- an entirely-different 

 pro. ess from that described In me for man. for in man the Sertoli 

 (ell- are tho-e that contain the differential in:; body. 



The de\e|opment of the human Sertoli cell is dearly a very 



beautiful case of -omatic differentiation. In fact, one may re- 

 gard the m u It ice] hi lar oivaiii-m a- ha\ in^ I \\ o period-; of -omaiic 



diiii n niiation: the first \\hen tin- ti ue cell- become differen- 

 tiated from the germ cells, and the second, when in the early mass 



n ( elK the primordial ^onad. the Sertoli cell- become dif- 

 ferentiated from the germ cell- proper. For the Sertoli cell- 

 ma\ piopeiK be classed as the soma of the testis. 



Nothing like the rod that differentiate- the human Sertoli cells 

 from the other ultimate spermatogonia -< em- to be known in any 



other case of somatic differentiation. In the classical case <>f 



. di-co\ered b>' lio\eri, pm-pecti\e bod\ cell- ca-t off into 

 the c\ topla-m the end- of their chn>mo-ome-. In cn|e|)od- and 

 insects, acconlin- to I lacker and >il\ e-lri n>pecti\ ely. a nucleolu- 

 or a mass "I nucleolar substance thro\\n out from the -erminal 

 V( icle of tin 'ine> ultimateK to lie in cell- of the germinal 



cycle. The origin of the rod of the human S.-rtoh cell- I c.iild 

 not determine, be\ olid that it i- lir-t apparent in the c\ topla-m 

 of the antepenultimate -permatogonia, and that it probably 

 form- then- during the re-i -tage of the cell-. It conn-, to 

 dc\elop in all antepenultimate -permatogonia, theref-ire. before 



