THE NUMBERS OF NORMAL AND ATRETIC OVA IN THE MATURE RAT

Abstract

There is no consensus about the part played by the germinal epithelium in oogenesis, nor is it established beyond dispute that oocytes continue to be produced throughout the reproductive life of an animal. Those, and to-day they are in the majority, who hold this latter view and who may, or may not, believe that germ cells are produced by the germinal epithelium, also as a rule maintain that oogenesis varies in intensity with the phases of the oestrous cycle. Allen [1923] made this point on the basis of counts of mitoses in the germinal epithelium of mice, and came to the same conclusion in further experiments [Allen & Creadick, 1937], in which the animals were injected with colchicine before death—a procedure which arrests mitoses at the metaphase stage. Similar experiments and similar observations have been reported by Bullough [1942a]. Neither of these authors, however, estimated the total number of