W. S. VINCENT 



Growth of the Starfish Oocyte 



In order to relate some of the chemical changes observed in the 

 nucleolus to oocyte growth, it was necessary to determine the 

 size relationships of the nucleolus, nucleus, and cytoplasm of 

 the starfish oocyte. The relationship between nucleus and cyto- 

 plasm in the starfish oocyte follows a rigid pattern during growth. 



125 r 



Fig. 1. Diameter of Asterias ruhens nuclei (large dots) and nucleoli 

 (small dots) plotted against oocyte diameter. Ordinate: diameter of nucleo- 

 lus or nucleus; abscissa: oocyte diameter in microns. 



Since I have been unable to determine an exact time scale for the 

 growth of the oocyte, changes in size of the nucleus and nucleo- 

 lus are plotted against oocyte diameter ( Fig. 1 ) . The relationship 

 shown here seems to be a general one for oocytes, as similar 

 gi'owth curves are found in amphibians (Gall, 1955) and in rats 

 (Vincent, unpublished data). The volume of nucleus and cyto- 

 plasm increases proportionately until the oocyte reaches about 

 one-half its mature size (Fig. 2). At this time the rate of cyto- 



