HISTOLOGY OF THE) OVIDUCT OF THE) DOMESTIC H^N. 42I 



Turning now to the epithelium in the uterine region we find, 

 as in the anterior parts of the oviduct, both the ciliated cells and 

 the unicellular glands. These present practically the same 

 arrangement and appearance as in the previous sections. Ex- 

 cept at their distal ends the cell boundaries of these epithelial 

 cells are very difficult if not impossible to see. The basal por- 

 tion of the epithelium appears as a syncytium. This appearance 

 may be due to the technique employed. 



From the above description and figures it is clear that in the 

 uterus the cells of the tubular glands have a somewhat different 

 structure from the cells found in these glands in other regions 

 of the duct. This difference in structure is undoubtedly asso- 

 ciated with the particular function of shell secretion which is 

 confined to the uterus. 



Histology of thf Vagina. 



The posterior end of the uterus is marked by the strong 

 sphincter muscle. The contracted portion of the oviduct ex- 

 tending from this sphincter muscle to the cloacal wall is known 

 as the vagina. As shown in figure 456 its walls are much con- 

 tracted. The inner surface is thrown into rather low longi- 

 tudinal ridges which appear in general to be continuous with 

 the folds in the uterus (fig. 456). The length of the vagina is, 

 on the average, about 12 cm. in the laying hen. 



Figure 473 represents a cross section of the wall of the 

 vagina under low magnification. The most striking character 

 in this figure is the great development of the inner (circular) 

 muscular layer. In the vagina this layer is several times thirker 

 than in any other region of the oviduct. The great develop- 

 ment of this muscular layer is naturally associated with the 

 need of expelling the egg which has acquired its full size and 

 is now a firm object upon which the muscles can act. The outer 

 longitudinal muscular layer consists of bundles of fibers scat- 

 tered through the connective tissue. Compared with the circu- 

 lar layer the longitudinal muscles are but poorly developed. 

 The connective tissue layers are similar to those in other parts 

 of the duct. 



As shown in figure 473. the longitudinal ridges in the vagina 

 region are low and rather narrow. The cores of these ridges are 

 filled with connective tissue and no layer of tubular glands is 



