MOUSE EMBRYO 



463 



*^.-/;J- 







hf'-- '^ 



3 









PHASES OF ESTRUS IN THE MOUSE 



1 . Diestnis - almost exclusively leukocytes. 



2. Pre-estrus showing both leukocytes and nucleated epithelial cells in approximately equal numbers. 



3. Early estrus - showing clearly defined epithelia cells, some with distinct nuclei. 



4. Estrus - large, squamous type epithelial cells without clearly defined nuclei. Many folds, thin 

 and transparent. 



5. Post-estrus showing again approximately equal numbers of leukocytes and epithelial cells, but the 

 latter are large, folded, and with translucent nuclei. 



(Mating occurs at stages 2 to 4 above, but these occur rather rapidly. The major part of the 5 day 

 cycle is spent in diestrus) 



