The Structure of the Mammalian Césophagus. 11 
cells. ‘There are no intracellular ductules. The crescents in the 
glands of the lower portion of the esophagus are not confined to the 
mucous portion of the gland, but occur also in groups along the ducts, 
alternating with the non-secreting cubical epithelium of the ducts, 
as shown in Fig. 4. 
The ducts of the glands are lined at their point of origin from 
the gland-tubule by a double layer of cuboidal cells. As they 
approach the surface the number of layers increases, there being a 
gradual transition to a stratified squamous epithelium. The majority 
of the ducts pass into the gland about the level of the deep border 
of the muscularis mucose. Frequently, however, they branch before 
penetrating the muscularis mucosee, and occasionally they receive 
a small group of mucous tubules in the lamina propria or in the 
muscularis mucose. There are no aggregations of lymphoid tissue 
around the ducts nor are the latter enlarged to form ampulle, as in 
the pig. 
The ducts of the superficial glands at the lower end of the cesoph- 
agus are more numerous and the glandular masses are less com- 
plex. The ducts here open into the depressions formed by the sec- 
ondary network of ridges on the surface of the folds and also at 
various points into the deep grooves between the principal folds. 
_ The glandular tubules are supported by a thin basement membrane 
of reticulum, between which and the bases of the cell fine fibres 
resembling myofibrille may be seen. The latter stain red in Mal 
lory’s reticulum stain, and probably belong to stellate cells (Korb- 
zellen), although this could not be demonstrated by the technique 
employed. 
The tunica muscularis consists in the upper third of the cesophagus 
of striated muscle. At the middle of the esophagus a few striated 
fibres are still to be found, but below this point it is all unstriated. 
RopeENTIA. 
The literature of this subject contains so many references to the 
structure of the cesophagus in Rodentia that it is unnecessary to 
describe in detail the conditions found in the different rodents exam- 
ined. It will suffice to discuss those structures which may be con- 
