i84 



ANATOMY OF THE DOMESTIC FOWL 



ridges (Fig. 60, A). The fimbriae are continuous with the dorsal 

 and the ventral ligament of the oviduct; and from this point, 

 where the ridges of the mucous membrane are almost nil, they 

 gradually increase in height as they extend down the tube. These 

 ridges are continued in those of the second, or albumin-secreting 

 portion (Fig. 60, D). At this point they increase in height very 

 rapidly. Here the bundles of muscular fibers of the middle coat 

 are thin and distributed among bundles of connective tissue. The 

 muscular fibers consist of two layers, an outer longitudinal and an 



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Fig. 60. — The mucous lining of the oviduct. 



A. Transverse section of the oviduct wall in the region of the neck of the- 

 funnel showing primary and secondary folding of the epithelium (after Surface). 



B. Showing the type of gland cells of the funnel region. 



C. Transverse section through the wall of the uterus showing the deep folds.. 



D. Section from the albumin-secreting portion showing the opening of a. 

 tubular gland and also showing the character of the cells. 



inner circular. At places in this portion the inner bundles may 

 be noted to extend longitudinally. In embryological development 

 the epithelial layer has an origin different from the outer layers of 

 the oviduct. In the fetal development the Miillerian duct arises- 

 as a thickening along the Wolffian body just ventral to the gonad. 

 This Miillerian duct is at first a solid cord of cells. It later develops- 

 a lumen, and grows posteriorly until it connects with the cloaca. 

 At the time of this posterior growth, mesenchyme cells migrate 

 in from the surrounding tissue and form a layer about the duct. 

 From this layer of mesenchyme cells there are developed the outer 



