DEVELOPMENT OF THE RECTUM 11 



Bii-mingham states that both the columns of Morgagni and the 

 rectal valves are distinct in embryos of four to five, six and nine 

 months. 



Glands 



Gsij (71) describes an elliptical ring of glands in the form of a 

 wreath around the anus. The ring he states is 1.25 to 1.5 cm. 

 broad and the inner border of the zone 1 to 1.5 cm. from the anal 

 opening. These 'circum-anal' glands have the structure of 

 sweat glands but they are considerably larger, being even larger 

 than the axillary glands. They are entirely absent in between 

 the ring and the anus where only sebaceous glands are to be found. 



Robin and Cadiat ('74) describe the manner in which the intes- 

 tinal glands leave ofT at the lower extremity of the rectum. When 

 seen in longitudinal section, the last four to six intestinal glands 

 are more closely packed together and their cells stain more 

 intensely. They emphasize the fact that there is a smooth zone 

 (the zone cutanee lisse) below the ano-cutaneous line which has a 

 stratified squamous epithelium, but which is lacking in hairs and 

 glands. As soon as the sebaceous glands begin, they are relative- 

 ly large. 



Herrmann and Defosses ('80) describe another type of gland 

 in the anal mucosa. They assert that at the bottoms of the 

 sinuses limited by the semilunar valves, the epithelium prolongs 

 itself in irregular canals which extend across the internal sphincter, 

 in contact with which they are frequently enlarged, forming 

 widened excavations. From these enlargements branch off sev- 

 eral ducts which are quite similar to gland tubes. The tubes 

 traverse the whole of the internal sphincter, and terminate in the 

 connective tissue interposed between this muscle and the longi- 

 tudinal layer of the muscularis. 



Herrmann ('80) goes somewhat more into detail in the descrip- 

 tion of the glands found in the anal region. Several types are 

 considered. 'Erratic glands' are intestinal glands which are found 

 below the ano-rectal line in the region of the zona columnaris. 

 They are few in number and are found only in a region a few mil- 

 limeters below the ano-rectal line. 'Isolated goblet cells' are like- 

 wise found for a short distance be^ow the ano-rectal line and finally 



