THE DEVELOPMENT OF THE MUCOUS MEMBRANE 



OF THE LARGE INTESTINE AND VERMIFORM 



PROCESS IN THE HUMAN EMBRYO 



FRANKLIN PARADISE JOHNSON 

 From The Harvard Medical School, Boston 



TWENTY-NINE FIGURES 



The following paper is the second of a series of studies con- 

 cerning the mucous membrane of the digestive tract. The 

 first (Johnson '10) dealt with the development of the oesopha- 

 gus, stomach and small intestine. The present paper is devoted 

 entirely to the large intestine, and includes all its parts except 

 the lower portion of the rectum. It is followed by an account 

 of the effects of distention upon the small and large intestines 

 of various animals. It is proposed to publish later an account 

 of the development of the anal portion of the rectum, work upon 

 which is nearly completed. The study of the mucous mem- 

 brane of the digestive tract was proposed to me by Dr. F. T. 

 Lewis in 1909, and as the work has progressed, I have received 

 from him many valuable suggestions. 



The development of the large intestine is of special interest 

 owing to the variety of pictures its mucosa presents. Relatively 

 simple in the beginning and again in the adult as compared with 

 other portions of the alimentary canal, the mucosa passes through 

 a number of complicated changes before it attains its full devel- 

 opment. To begin with, the smooth epithelial tube of the large 

 intestine develops more or less regular longitudinal folds. These 

 folds, as will be subsequently described, are later replaced by 

 villi. Still later the villi themselves disappear. Meanwhile, 

 glands are forming, and when the villi have entirely faded out, 



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