n6 THE PHYSIOLOGY OF REPRODUCTION 



which chiefly concern the chromatin of the nucleus may be 

 summarised as follows: 



I. Early changes : () 1'rotobroquc cells, Variety a. The nuclei 

 are granular in appearance, the chromatin is arranged irregularly, 

 and there is no reticulum. These are the original germinal epithelial 

 nuclei. (6) 1'rotobroque cells, Variety /'.The cells belonging to 



Early ovojjcnetic .-t;iu r >'. 



I .< I (tut on if s 



Fn.. I'M. I >rv..-li.|iing ova from ovary two days before birth. (After 

 Lane-Clay ]>"i i. 



variety a divide, and give rise to mure cells of the same kind, as 

 well as to protobroque cells of the 1> variety. In the latter the 

 nuclei are Irs- granular, and contain a certain number of fine 

 chromatin filaments. (>) I >eutobroque cells. The protobroque cells 



Syn;i|>t'HK stage. /,'/<. 



KH.. 30. -Developing ova from nvary alx.ut one day before birth. 



(Aftoi I.aii.--( 'la\ IK>II.) 



<>f the 1> variety likewise dividr, and give rise to more protobroque 

 cells, similar to themselves and also to deutobroque cells. These 

 latter are larger in si/e, and contain nuclei with the chromatin 

 arranged in the form of a reticulum. 



II. Later changes: (//) Leptotenic stage. Certain of the 

 deutoliro.pie nuclei become gradually differentiated, the cliromatin 

 during the lej>totenic stage passing through a process in which it 

 breaks up into fine filaments; these are distributed over the nuclear 

 region. <M Syiuptenie sta^e. The filaments become congregated 



