138 CYCLIC CHANGES IN THE OVARIES AND UTERUS OP THE SOW, ETC. 



There is also a wave of mitotic division in the gland cells, which does not begin, 

 however, until the ova are about to pass into the uterus (3 or 4 days after ovulation) . 

 In the superficial gland tubules the mitoses cease simultaneously with those of the 

 surface epithelium, about the sixth or seventh day, but in the basal glands a few 

 mitotic divisions may be seen a day or two longer, even after degeneration of the 

 ova and establishment of the high columnar surface epithelium. 



Eosinophil poly morphonu clear leucocytes, which are always present in small 

 numbers in the uterine stroma, especially in the more superficial portions, undergo 

 a great increase in number during the first week after ovulation. Unlike the neu- 

 trophils of the cestrous stage, the eosinophils do not invade the epithelium, but 

 remain in groups about the vessels and glands of the superficial zone. 



There is a marked reduction of the edema of the stroma at the conclusion 

 of cestrus, so that the connective tissue and the structures passing through it are 

 again condensed into somewhat smaller compass. 



STAGE OF EIGHT TO TEN DAYS AFTER OVULATION. 



(Figures 21, 24, plate 3; 28, plate 4.) 



The surface epithelium now presents a striking contrast to its former appear- 

 ance, for its cellular elements are tall and narrow and ranged in simple columnar 

 form. The relative proportion of cytoplasm to nucleus is 

 The ova have degen- g rea % increased and the nuclei generally occupy a central 

 erated and disappeared, position. The cells vary in height from 20 to as much as 



Had they been fertilized , e j j i j.i_ j_i e 



they would now be large 4 ^ nucra, and are arranged in such a way that the surface 

 biastodermic vesicles, not formed by their free ends is not smooth but wavy, giving rise to 



yet fixed to the uterine ,. , , . , , ... 



mucosa. Corpora lutea little hillocks, between which are depressions or pseudocrypts 

 fully organized. (fi g- 21, pi. 3). As we shall see, this arrangement aids in 



giving the mucosa, in the gross specimen, a soft and velvety 

 texture. The whole appearance is now that of an actively secreting epithelium. 



At this stage one notes particularly well a detail which has often been com- 

 mented upon by observers of other species, including the human, and which is seen 

 at all stages of the cycle, namely, the presence between the normal epithelial cells 

 of others which are compressed laterally, have darker-staining cytoplasm, and 

 usually compressed pycnotic nuclei (fig. 28, pi. 4, i. c.}. They have been called 

 "Stiftchenzellen," "cells with pycnotic nuclei," "intercalar cells," etc., and have 

 been variously interpreted. I can see no reason to doubt that view which holds 

 them to be degenerated cells in the act of extinction. Here and there one also sees 

 small cells of uncertain provenance, with dense, round nuclei, which seem to have 

 intruded themselves into angles at the bases of the tall epithelial cells upon the 

 basement membrane. 



At this time the invasion of the more superficial parts of the stroma by eosinophil 

 leucocytes (described in last section) is at its height, as shown in figure 24, plate 3. 



The cells of the superficial gland tubules now undergo a slight enlargement. 

 From the seventh to the tenth day of the cycle they measure from 18 to 30 micra, at 

 all other times from 15 to 20 micra. Likewise, the cells of the basal glands gain 

 a little in height, exceeding their usual limit of 10 to 15 micra and gaining a 



