Histochemical and ultrastructural features

Abstract

The developing enteric nervous systern of the hurnan foetus has been analyzed at the 10th and 18th week of gestation with a special reference to the development of nerve-rnuscle contacts. The rnyenteric plexus forrnation was analyzed by rneans of electron microscopy and on whole-mounts after NADH diaphorase histochernistry. The developrnent of noradrenergic innervation as an extrinsic inhibitory supply was followed by means of a glyoxylic acidinduced fluorescence rnethod. Differentiated neurons and neuroblasts both occurred in rnyenteric ganglia of the 10- and 18-week-old foetus although the ganglionic neuropil was almost unidentifiable ultrastructurally at the 10th week of gestation but was rnature looking at the 18th week. The nerve plexuses connecting the ganglia frequently forrned distant and close rnyoneural contacts. NADH-diaphorase histochernistry revealed that in the 18-week-old hurnan foetus rnost of the neural perikarya was within the ganglia. Also, at the 18th week of gestation a well-defined fluorescent network was dernonstrated within the ganglia, as well as in the internodal segrnents. On the basis of these observations we concluded that the time between the 10th and 18th week of gestation has pararnount irnportance for both the rnorphological and functional rnaturation of the enteric nervous systern.