AbstractA light microscopic study of the endocrine pancreas in some myxinoids has revealed a striking difference in the occurrence of follicles. Islet tissue follicles are regularly occurring and also abundant inMyxine glutinosa, but are sparse or absent inEptatretus burgeriandEptatretus stouti.Whether this is caused by a decreased need for insulin inMyxine glutinosais discussed but remains an open question.