THE MITOTIC CYCLE 



Growth in interphase 



One of the factors which influence the nuclear size in rapidly growing 

 tissues is the stage which a nucleus has reached in its period of growth 

 in interphase. According to Conklin,^^* in the embryo of the mollusc 



Figure i8. Various sizes of spermatocyte nuclei in Arvelius albopunctatus (a, c and 



d) all form chromosomes of the same number and size (b and e). Diakinesis and 



metaphase I in 4th lobe of testis (a and b) ; in 5th lobe (c, d and e) X 1500. From 



Schrader182 {By courtesy, Chromosoma). 



Crepidula the interphase nucleus enlarges most rapidly as the next 

 mitosis approaches, while in cells of the mouse spleen in tissue culture 

 (Fell and Hughes^^^) two-thirds of the full interphase size is reached 

 within three hours of telophase (Figure 19). A number of authors 

 believe that the growth of resting nuclei is discontinuous and rhythmic. 



56 



