CYCLIC CHANGES IN THE OVARIES AND UTERUS OF THE SOW, ETC. 139 



dimension of 15 to 20 micra. This enlargement of the gland cells is due to an 

 increase in the relative amount of cytoplasm, so that they also gain an appearance 

 as of active serious secretion. It should be mentioned here that at no time are 

 there any marked changes in the morphology of the glands like those described in 

 the human uterus by Hitschmann and Adler (1908) and others. 



STAGE OF THE TENTH TO THE FIFTEENTH DAY. 



(Figure 22, plate 3; 29, plate 4.) 



The stage of high columnar epithelium is succeeded about the tenth day after 



ovulation by another phase, which is characterized by a further modification of the 



surface epithelium. This consists of a reduction of the cells 



No ova in the uterus; to a ^ ow columnar form, measuring from 15 to 20 micra, and 



had they been fertilized by the extrusion (from the surface of each cell) of cytoplasmic 



gtL^aCrintTthe processes ranging from 3 to 8 micra in height, which will be 



uterus. Corpora lutea in more readily comprehended by study of the illustrations than 



a fully developed stage ,. i_ i j j. T v j ji 



until degeneration sets in from Verbal descriptions. In SOme preparations the appear- 

 on the fifteenth day. ance j s as if the free ends of the cells were frayed and eroded; 

 in others the processes are rounded or pointed, and sometimes 

 they might almost be taken for poorly fixed or agglutinated cilia, except for the 

 absence of the basal granules which mark all true cilia in the uterine glands. (Com- 

 pare fig. 29, pi. 4, with fig. 17, pi. 2.) 



We shall have occasion to return, in a later section, to the consideration of this 

 very peculiar change of the epithelium. There appear to be no similar observa- 

 tions on record except those of Hitschmann and Adler (1908), who describe (in 

 the late-interval and premenstrual stage of the human uterus) epithelial cells 

 with frayed-out surfaces, and of Geist (1913), who illustrates, also in the human 

 premenstrual stage, rounded protuberances very much like those of the pig. Geist 

 considers that the protuberances consist of a secreted substance passing out of the 

 cells into the lumen; but as far as our specimens are concerned there seems to be 

 no reason for thinking them other than a modification of the superficial cytoplasm. 



Coincident with the lowering of the height of the epithelial cells, there is a 

 disappearance of the complex hillocky arrangement of the surface. The gland 

 epithelium now returns to its usual size and the excess of eosinophil leucocytes 

 disappears from the subepithelial stroma. 



STAGE OF THE FIFTEENTH TO THE TWENTIETH DAY. 

 (Figure 23, plate 3; 30, plate 4.) 



During the few days previous to a new ovulation the surface epithelial cells 



become so low (15 to 20 micra) that in some preparations they are 



During the latter part f cuboidal form, hardly higher than their own nuclei. The sur- 



of this stage a new group f ac e protuberances diminish in height and finally disappear as 



of follicles is prepared for ,, ,, , . , j-j. j J.-G J 



ovulation. The corpora the cells once more begin to be arranged into a pseudostratmed 

 lutea are degenerating. epithelium. This stage marks what might be called the comple- 

 tion of the cycle; in the pig it is of brief duration, but in the sheep, 

 where there is a long anoestrous period, the uterine mucosa apparently remains in 

 such a resting stage during the 10 months or more of interval. 



