THE OESTROUS CYCLE IN THE MOUSE 313 
during the D stage. The gland ducts are distended and their 
cell outlines are clearly defined. Mitoses are absent, which indi- 
cates little growth activity in the glands during hyperfunction. 
Glands are distributed evenly throughout the mucosa except 
opposite the line of the attachment of the broad ligament. 
The nuclei in the stroma are densely packed, possibly because 
of distention of the lumen. 
The oviducts are slightly distended. Their epithelium is in 
good condition in the non-ciliated portions. In the ciliated seg- 
ment, all stages in the process of extrusion of nuclei are apparent, 
but to a less degree than in the D’stage animal previously de- 
scribed. No leucocytes are present. 
There are no ova to be found in either oviduct. Therefore, 
if ovulation occurred at the last O period, that should have 
been at least four days before death. 
Sections of the ovaries show a marked hyperemia. ‘There 
are two sets of follicles containing liquor, the first one composed 
of ten follicles, which are large and distended with considerable 
amounts of liquor. They are all superficially located. The 
cumuli are intact and still solid masses of cells. The nuclei of the 
ova are in a resting condition. The second set of follicles is 
less mature, being medium sized, with the liquor still confined 
to small pools at the poles of the follicles. 
There are several medium-sized atretic follicles in which the 
cells of the cumuli have entirely degenerated, leaving the ova 
free in the liquor. The granulosa cells also show marked signs 
of atresia. 
The ovaries of this animal are unusually large, which may be 
partly accounted for by their hyperemia, but the unusual num- 
ber of corpora lutea is probably the main reason. At first glance 
the ovaries appear to be just large masses of corpora lutea. 
Three sets are easily distinguishable. Those of the first set are 
superficial, medium sized, and stain dark blue. Their central 
lakes are completely ingrown, but two of them show small patches 
of red blood corpuscles at their centers. They are at least four 
days old. : 
THE AMERICAN JOURNAL OF ANATOMY, VOL. 30, NO. 3 
