DEVELOP.\Ip]NT OP^ THE RECTUM 



25 



villi which are similar to those found in other parts of the large in- 

 testine. Intestinal glands are distinctly seen in the figure but the 

 villi are in most places quite low. The epithelium lining this 

 portion of the rectum is simple columnar, composed of cells with 

 a clear ]irotoi)lasm, many of which are goblet cells. At the basal 



Ir.coI.ep 



str.col.ep. 



sir. sq. ep. 

 'uqW. pill. 



Fis- 2 A, Reconstruction of the lower part of the rectum of an embryo of 1.3") 

 mm. X •'). /:?, '''. Z>, E. F . Successive sections taken at the levels as shown in .1 . 

 X lo. /"//. /'//''. hair follicle; tjLitd., intestinal gland; s.col.cp., simple columnar 

 epitheliimi; slr.i-Dl.ep., stratified coUunnar epithelium; str.sij.ep., stratifie<l scjua- 

 mous epithelium. 



ends of the glands a thin zone of develoi)ing muscle fibers, the 

 muscularis mucosae, (0.018 mm. in thickness) is apparent. The 

 muscularis proper is well developed, both layers forming contin- 

 uous rings around the epithelial tube (together 0.117 mm. thick). 

 Between the two layers of the nuiscularis are seen numerous ner\e 



