334 EDGAR ALLEN 
following ovulation are brought about by a disintegration of 
some of the epithelial cells.”” Stockard and Papanicolaou (717), 
also working with the guinea-pig, say: ‘“‘Large vacuoles are 
to be seen between the epithelial cells, and these are probably 
produced by the dissolving power of the leucocytes.’”’ Long and 
Evans (’20) state that destruction in the uterine epithelium in 
the rat is due to ‘vacuolar’ degeneration. <A closely timed series 
of material in the mouse shows distinct degenerative changes 
evident in the substitution for the basement membrane of a 
light staining zone before leucocytosis begins. It seems more 
probable that these vacuoles in the uterine epithelium are com- 
parable to those in the oviducts (where no leucocytosis occurs) 
and are evidences of degeneration which may be the cause of 
the leucocytosis. The evidence from the mouse indicates that 
epithelial degeneration is a primary, and the leucocytosis a 
secondary, phenomenon. 
4. Regenerative changes. Many regions of the surface uterine 
epithelium as well as the glands escape destruction during a 
single metoestrum in the mouse. Also when active mitosis 
begins it does not appear to be restricted to regions adjacent to 
the openings of the gland ducts. 
5. The distribution of glands. The distribution of glands 
throughout the uterine mucosa seems possibly to be of some 
significance in the consideration of the implantation of the 
blastocysts. Huber (15), in his contribution to the embryology 
of the albino rat, calls attention to the even spacing of the im- 
plantation sites which are ranged along the sides of the cornua 
adjacent to the attachment of the uterine ligaments. In the 
mouse, in all the animals studied, glands were distributed every- 
where throughout the mucosa except along this line. That 
this is the future site of placentae is interesting. 
c. Cyclic changes in the oviducts. 1. The oviducts seem to 
have been overlooked by most investigators in considering 
degenerative changes during the oestrous cycle. So far as I 
have been able to find, no cyclic degenerative changes have been 
reported in them in the lower mammals. In summarizing the 
discussion of the question in man, Novak (’21) disposes of the 
fs 
