Schistosoma mansoni: the development of the cercarial tegument

Abstract

Young cercariae were covered with a thin nucleated primitive epithelium which was lost when the true tegument appeared beneath it. The tegument was at first similar to the primitive epithelium in that it was a nucleated, cytoplasmic syncytium but it could be distinguished from the primitive epithelium by its thickened outer membrane and by the layer of interstitial material beneath its basal membrane. The tegumental nuclei became pycnotic and disappeared and, at about the same time, nucleated subtegumental cells became continuous with the tegument. Two types of small, dense bodies were formed in the subtegumental cells and passed into the tegument. Later in development the tegument became filled with dense, granular material and spines were formed. The fully developed cercarial tegument was covered with a surface coat of fibrous material which was specifically attached to the outer membrane of the tegument.The observations described in this paper formed part of a thesis approved by the University of London for the Degree of Ph.D.