DEVELOPMENT OF THE GUT IN XENOPUS-LAEVIS

The lining of the gut, together with the pancreas, liver, gall bladder , and respiratory system, is formed from the endoderm, The gut also co ntains smooth muscle and connective tissue of mesodermal origin. The a mphibian Xenopus laevis is potentially an excellent model organism for studying how the cells of the endoderm and mesoderm become programmed to produce these internal organs. However, the anatomical complexity of the coiled gut presents a problem in studying its development. In o rder to overcome this problem we here present a comprehensive guide to the anatomy and histology of the developing Xenopus gut. We use a sim ple dissection to display its anatomy and the expression of four endod ermal markers (alkaline phosphatase, IFABP, XlHbox8, and endodermin), We present schematic diagrams that show how the gut is arranged in thr ee dimensions and how this organisation changes during development, We also present drawings of histological sections of the gut which allow any region to be identified and so represent an atlas for working wit h sections. Finally, we describe the histology of the cells of the var ious organs of the gut. This histological identification may be necess ary for the identification of parts following experiments in which the normal pattern is disturbed. (C) 1998 Wiley-Liss, Inc.