1 86 ANATOMY OF THE DOMESTIC FOWL 



It is probable that the secretion of albumin is not confined to the 

 cells of the second division; yet we are safe in saying that the major 

 portion is formed here. The folds of mucous membrane in this di- 

 vision are thicker and higher than in the funnel, due to their con- 

 taining cells of the high columnar type, and to the fuller development 

 of the glands which are of the tubular variety. The muscular layer 

 is heavier, and therefore the muscular power to force along the 

 tubes' contents is greater. In the formation of the mucous folds we 

 find, in transverse sections, that the central core is made up of con- 

 nective tissue which carries blood-vessels and nerve filaments, as 

 in other similar glandular structure. The epithelium contains glan- 

 dular cells of two varieties, namely, the ciliated, columnar variety, 

 and the unicellular, goblet variety (Fig. 36, No. B, 2). These two 

 kinds of glandular cells are rather evenly distributed throughout the 

 epithelium of this section of the oviduct. The unicellular gland cells 

 are more numerous at the mouths of the ducts leading from the tu- 

 bular glands. The nuclei of the ciliated cells are oval and lie near 

 the middle of the cells or a trifle toward the base from the middle. 

 The protoplasm of the cells is finely granular. Strong cilia in con- 

 siderable number surmount each cell. In some cases the goblet or 

 mucous cells have pushed apart the ciliated cells, and their prolon- 

 gations extend farther than the surface of the ciliated cells. The 

 nuclei of the goblet cells are round, and lie nearer the proximal 

 end than those of the ciliated cells. 



The third division of the oviduct, the isthmus, continues from the 

 albumin-secreting portion and terminates in the expanded portion 

 called by some anatomists, the uterus. Toward the posterior 

 end of the albumin-secreting portion the longitudinal folds of mu- 

 cous membrane become lower, making, at the juncture of this and 

 the isthmus, a clear line of demarcation. For a distance of 2 

 or 3 centimeters the folds are low, after which they gradually 

 become higher, but never reach the height or thickness of those in 

 the albumin-secreting portion. 



The clear-cut line between the albumin-secreting portion and 

 the isthmus is partly due to a zone in which the long tubular glands 

 are lacking. The core of the folds of mucous membrane in this 

 zone contain much more connective tissue. The cells are both 

 ciliated and unicellular. The rest of the histological structure of 

 the isthmus is the same as that of the albumin-secreting portion. 



