MORPHOLOGY AND DIFFERENTIATION OF THE CELOMOCYTES OF THE FREE-LIVING STAGES OF NIPPOSTRONGYLUS-BRASILIENSIS

With the use of observations on living and fixed and stained larvae of Nippostrongylus brasiliensis reared in charcoal-feces cultures, an in tegrated view is presented on the morphology and differentiation of th e coelomocytes. present in the body cavity of the 2 rhabditiform stage s and the exsheathed third stage. Four coelomocytes are present in the newly hatched larva arranged linearly from the base of the esophagus to the genital primordium. They lie subventrally, the anterior 2 on th e right side of the ventral nerve cord, the posterior 2 on the left si de. Data on the growth of these cells and analysis of their fixed site location in the coelom are presented. The coelomocytes are firmly att ached to the inner surface of the body wall by filopodia. However, abe rrantly positioned coelomocytes suggest the possibility that detachmen t and migration may occur. A few minute cytoplasmic inclusions are pre sent in the coelomocytes in living newly hatched larvae and may reach approximately 100 or more in each coelomocyte in the third stage. Thes e inclusions exhibit 2 phases of a pigmentation process. They are colo rless in the rhabditiform stages, but simultaneous with the initiation of the second molt to form the infective larva, the inclusions rapidl y turn a pink to rose hue. A variety of previous experimental data str ongly support the interpretation that the pigment represents an extrao rdinary concentration of vitamin B-12 in the coelomocytes obtained by larval feeding on bacterial B-12 synthesizers present in the charcoal- feces cultures.