The alligator and its allies . greater thickness of the constituent layers, espe-cially the mucosa. The mucosa is also thrown intomore numerous and complicated folds in the anteriorthan in the middle and posterior regions; thecomplexity of the mucosa seems to diminish asthe intestine is followed caudad. In the anteriorregion the mucosa may form at least one half of the^entire thickness of the wall, while in the posteriorregion it ma3^ form less than one third of thethickness of the intestinal wall. The minutestructure of the intestinal epithelium will be de-scribed below. The chief peculiarity
The alligator and its allies . greater thickness of the constituent layers, espe-cially the mucosa. The mucosa is also thrown intomore numerous and complicated folds in the anteriorthan in the middle and posterior regions; thecomplexity of the mucosa seems to diminish asthe intestine is followed caudad. In the anteriorregion the mucosa may form at least one half of the^entire thickness of the wall, while in the posteriorregion it ma3^ form less than one third of thethickness of the intestinal wall. The minutestructure of the intestinal epithelium will be de-scribed below. The chief peculiarity of the intestinal wall isthe apparent total absence of a submucosa(Fig. 47). As will be described later, the mucosalepithelium is laid upon the usual bed of fibrousand lymphatic tissue, the tunica propria (, tp) The Digestive System i8i At the outer border of the tunica propria, andwith no tissue corresponding to a submucosabetween it and the circular muscular layer, is athin and indistinct layer that has the appearance. Fig. 47. A transsection of the wall of the anterior region of the smallintestine of the hibernating animal, under low magnification; hi, lymphnode; Ip, tunica propria; other letters as in Figure 42. of a longitudinal layer of muscle fibers; this shouldcorrespond to the muscularis mucosa (Figs. 47, 48,49, and 51, mm). The circular, cm, and longitudinal, Im, musclelayers are compact, and are distinct from theother la3^ers of the wall; the former is approxi-mately twice the thickness of the latter. Therelative thickness of all the layers in the three 182 The Alligator and Its Allies
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1915
