324 EDGAR ALLEN 
band which includes the basal sides of the epithelial cells and the 
superficial stroma. This is quite marked in the M, stage before 
leucocytosis has begun, which would indicate that the destruc- 
tion of the epithelium by leucocytosis is secondary to degenera- 
tive changes in that tissue. It is in this subepithelial zone that 
the leucocytes collect in greatest numbers and from which they 
further invade the epithelium. <A few places appear to be ex- 
empt, retaining their healthy appearance. Seldom is a region 
found entirely denuded of its epithelium, but this tissue becomes 
markedly degenerate (figs. 14 to 16). This material does not 
show greater numbers of mitoses in the uterine epithelium near 
the openings of the gland ducts than in other regions. 
5. Changes in the oviducts 
The oviducts apparently escape entirely the periodic leucocy- 
tosis, so extreme in the rest of the genital tract. They do exhibit — 
definite cyclic changes, however. Earlier in this paper the ovi- 
ducts have been divided into segments distinguishable by the 
presence or absence of cilia, the height of the folds of the mucosa, 
and the thickness of the muscle layers. The segment leading 
from the periovarian sac is ciliated, the remaining portion has 
simple non-ciliated columnar epithelium. 
During the P and O stages the nuclei of the ciliated portion are 
ranged in a quite regular row. As the M, phase of the cycle 
advances, some of them migrate to the free ends of the cells 
which loose their cilia and through which these nuclei are ex- 
truded. They may retain the appearance of normal nuclei 
or become pycnotic before they are extruded, but when lying 
on the free surface of the epithelium, are shrunken and dark 
staining. This process reaches its height during the M, and 
early D stages, at which time the epithelium may become greatly 
vacuolated. It is therefore of degenerative significance (figs. 
18 and 19). 
The non-ciliated portions of the uterine tubes also show vary- 
ing degrees of vacuolization, which seems to result from a hyper- 
secretion of this epithelium. As yet it has not been possible to 
correlate this with definite phases of the oestrous cycle. | 
a 
