Mucous Membrane in the Human Embryo. 529 
6, from an embryo of 55 mm., shows one half of a model viewed 
from its inner surface. The stippled areas represent those covered 
with cilia. As can be seen, the larger areas of ciliated cells are 
on the folds and these areas include but few islands of polygonal 
cells. Between the folds there is a preponderance of squamous 
cells, which are interrupted by a few small ciliated patches. In 
the upper part of the cesophagus the ciliated areas are slightly 
larger than in the region modelled. A similar reconstruction was 
made of the epithelium of the cesophagus at 99 mm. (fig. 7). It 
shows that the amount of ciliated surface has actually and rela- 
tively increased and there are now more islands of polygonal cells 
on the folds. 
In embryos of 120 mm., 134 mm., and 187 mm., ciliated cells 
in the cesophagus are observed to be distributed in about the same 
proportions as at 99 mm. At eight months the upper part of the — 
cesophagus shows only a few small patches of ciliated cells. In 
a specimen at birth the areas are abundant but proportionately 
smaller than in the earlier stages, and the islands are now more 
widely separated. The islands consist of distorted columnar cil- 
iated cells, the distortion probably being due to the pressure of 
the rapidly increasing polygonal cells, which are seen crowded 
closely against the islands and in places partly undermining them. 
In a child of two weeks (7 months premature birth) no ciliated 
cells can be found in any part of the cesophagus. Jahrmaerker 
and Schridde were unable to find ciliated cells at birth. 
Glands. In regard to the glands of the cesophagus, there are 
two distinct types to be considered; the true or deep cesophageal 
glands, and the cardiac or superficial cesophageal glands. The 
former are found in the adult all along the cesophagus, with the 
exception of the lower 2 to 4 mm. of its length; the latter in the 
lower 2 to 4 mm. and also (70 per cent of cases examined by Schaf- 
fer) in that portion of the upper part of the cesophagus which lies 
between the level of the cricoid cartilage and the 11th tracheal 
ring. 
In an embryo of 78 mm. (incomplete series 723 and 724) small 
patches or islands of glandular epithelium are found in both the 
upper and lower ends of the cesophagus. Schaffer (’04) described 
