The feeding site and probable feeding mechanism of the parasitic nematode Capillaria hepatica (Bancroft, 1893)

Abstract

Examination by light and electron microscopy of the tissue surrounding the anterior end of the trichuroid nematode Capillaria hepatica in the liver of its mouse host indicates that the nematode is enclosed by multinucleate cytoplasmic masses originating from parenchymal liver cells. These cytoplasmic masses have desmosomal contacts with adjacent cells. Nuclei often have an irregularly expanded nuclear envelope, greatly increased amounts of heterochromatin or increases in interchromatinic and perichromatinic granules, and segregated nucleolar components. Mitochondria are swollen and endoplasmic reticulum is swollen or vesiculated to varying degrees. The outer cell membrane of the cytoplasmic masses is thrown into extensive irregular folds, but on the surface next to the nematode, no cell membrane can be found. As the nematode's intestinal contents include remnants of cellular materials, it seems likely that the nematode feeds upon the cytoplasm surrounding its anterior region. Unsuccessful attempts to demonstrate the uptake of trypan blue, colloidal gold, or ferritin injected into the host's circulatory system further suggest that this nematode feeds from the induced host reaction rather than from blood or tissue fluids.