Proliferation and renewal of the epithelium in the intestine of young adult anadromous sea lampreys, Petromyzon marinus L.

Abstract

The pattern of incorporation of [3H]thymidine in the intestinal epithelium of young adults of the anadromous sea lamprey, Petromyzon marinus L., was examined for up to 41 days using autoradiography. Compared with haemopoietic tissue of the fat column and the epithelium of the kidney, the intestinal epithelium does not rapidly incorporate the isotope. The epithelia of the anterior and posterior intestines and the hindgut regions all undergo a proliferation which, based on changes in the labelling index through time, suggest that a renewal of the epithelium takes place in each region. Most of the cells undergoing cell division are specialized absorptive cells but, in the posterior intestine and hindgut, mucous cells also undergo a variable rate of division. Although there is a slightly greater frequency of labelled cells at the bases of the longitudinal folds, there are no definite zones of proliferation in any region of the intestine. Instead, patches of dividing cells appear throughout the height of longitudinal mucosal folds. This is similar to the situation in parts of the intestine of larval lampreys and the intestine of amphibian tadpoles but unlike the case in other fishes.