THE OESTROUS CYCLE IN THE MOUSE 303 
Cut surfaces were oriented so that the same regions in different 
animals could be compared (text fig. 1). 
3. POINTS OF IMPORTANCE IN THE ANATOMY OF THE GENITAL 
ORGANS OF THE MOUSE 
There are some points in the anatomy of the genital organs of 
the mouse which need emphasis since they have an important 
bearing on certain aspects of this work. 
Text fig. 1 Genital organs before fixation, showing the planes of histologica 
sections. A, body of uterus; B, vagina; C, middle of left cornu of uterus; D 
middle of right cornu; EH, left ovary and oviduct; F, right ovary and oviduct 
H, sagittal section of phallus and lower vagina. 
The vagina in the mouse opens directly on the vulva without 
the protection of any structures homologous to the labia minora. 
Its stratified epithelium is devoid of glands. The phallus is 
large and prominent and is traversed in its entire length by the 
urethra. The cervix is relatively short, the division into the 
lumina of the uterine cornua occurring 1 to 3 mm. above the 
opening of the external os. A stratified epithelium, similar, 
