The Fine Structure of the Gametocytes of an Adeleine Haemogregarine

SYNOPSIS. Gametocytes of an unidentified haemogregarine (Sporozoa, Telosporea, Coccidia, Eucoccida, Adeleina, Haemogregarinicae) from the frog Rana montezumae were examined by light and electron microscopy. The fully-grown gametocytes lay in a vacuole in the erythrocyte, surrounded by a sheath which was probably of parasitic origin. The gametocytes were bounded by a pellicle of 2 unit membranes, beneath which lay a ring of small longitudinal fibrils. At the anterior end there were 2 concentric layers of larger longitudinal fibrils, arranged in a truncated cone, lying between the pellicle and the cytoplasm of the parasite. The cytoplasm contained a few small mitochondria, many inclusions resembling lysosomes, and small vacuoles; there were also 2 larger, anterior inclusions, which did not appear to run to the tip of the organism. Numerous ribosomes were seen, but no endoplasmic reticulum. The single nucleus contained discrete, dense, granular masses, perhaps deoxyribonucleoprotein, and was apparently limited by only a single membrane.