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



roughly guess that in this region one-fourth of the gland cells are ciliated. In the 

 basal zone the ciliated cells seem fewer and the cilia are slighter and less obvious 

 because packed into a narrow lumen (fig. 18, pi. 2, a) ; but when by chance a dilated 

 gland is found they can be seen to good advantage (fig. 18, pi. 2, 6). If a small 

 piece of the fresh uterine mucosa is snipped off and flattened under a cover-slip, the 

 cilia may be seen beating within the glands. It was by this method, and in 

 fact with tissue from a sow, that the cilia of the uterine glands were first discovered 

 by Nylander in Leydig's classroom (Leydig, 1852). 



There is no evidence to indicate that there is other than a serous secretion 

 from either glands or surface epithelium. There are no goblet cells in the uterine 

 epithelia of the sow, and careful microchemical tests for mucin in smaller masses 

 give negative results. Equally negative were the results of an effort to demonstrate 

 unsaturated neutral fats by means of osmium tetroxide. The statements of 

 Wegelin (1911), that there is a cyclic variation in the amount of glycogen demon- 

 strable in the human uterine mucosa, suggested a similar study of the sow's uterus, 

 especially since we had already observed glycogen in the fetal membranes in early 

 pregnancy; but no glycogen could be demonstrated, either by Best's carmine method 

 or by iodine after alcohol fixation, in any part of the uterine mucosa of the non- 

 pregnant sow at any stage of the cycle. 



The stroma of the uterine mucosa is no more nor less than a rather gelatinous 

 or fluid-infiltrated areolar connective-tissue, through which course the glands, 

 blood-vessels, lymph-vessels, and nerves, and which contains in the meshes of its 

 fibers the various cells of areolar tissue, namely, fibroblasts, macrophages ("clas- 

 matocytes"), plasma cells (often very numerous, but varying without reference 

 to the cycle), and the various leucocytes. There is a slight condensation of the 

 stroma just under the surface epithelium, forming a narrow subepithelial connec- 

 tive-tissue zone, of which the most superficial fibroblasts are flattened against the 

 epithelium to form a basement membrane. 



The blood-vessels (fig. 19, pi. 3) pass through the muscularis, giving off branches 

 to plexuses in and between the muscular layers, and then form a network of large 

 channels near the base of the stroma. From this network long loops ascend toward 

 the lumen, to end in a delicate capillary plexus in the subepithelial tissue, just 

 below the epithelial cells. 



THE UTERUS DURING OESTRUS. 



(Figure 20, plate 3; 25, 26, plate 4.) 



During the days of oestrus the uterine epithelium has a total thickness of 25 to 



30 micra. As shown in the figures, it is not obviously columnar, but presents an 



arrangement which is deceptively suggestive of stratification. 



Ova maturing in the The cells are so closely compressed together laterally, and at 



Graafitm follicles, or dis- , . , . , , . , 



charged and in passage the same time have attained so low a form, that they are 

 through the tubes. Ear- ra ther irregularly packed and the nuclei thus appear to be 



liest stages of the corpora 11 /-, 



lutea. arranged in several layers. On careful study many of the cells 



appear to extend from base to surface of the epithelium, but 



