Morphogenesis of the larval stage — the cysticercus

Abstract

Little information is available on the further development of the oncosphere after its location in the intermediate host. The embryo having shed its embryonal hooks represents an aggregation of cells. Mostly only its transformation into a bladder with a distinct doublelined membrane has been recorded. Young (1908) making a detailed study of the very early stages of C. pisiformis concluded that this bladder consists of the loose syncytium of several parenchyma cells with a network of cytoplasmic processes and fibrils. The spaces within the cellular network seem to be filled with tissue fluid. In this developmental stage, the surface of the formation consists only of parenchyma. Later, the fibrils under the surface of the larva become arranged into two layers and gradually start to multiply and join into bundles. The cells start to concentrate more densely below this arrangement of the surface of the body to form the future subcuticular cell layer. Thin processes, running out of these cells, are in connection with the superficial fibrillar layer which, after being thickened by a further deposition of cement substance, differentiates on its surface a cuticular border of delicate hair-like processes. Some of the subcuticular cells differentiate into muscle cells and later form two layers of muscle fibrils lying perpendicular to each other. This differentiation of the bladder wall occurs simultanously with the formation of the central cavity of the mother bladder.