The ultrastructural findings on the kidney cells of the gerbil Meriones crαssus have shown the presence of finger-like projections emerging from the basal part of the epithelial cells of the proximal convoluted tubules into the matrix of the thick basal laminae and that structure like membrane-bound bodies are commonly seen in continuity with these processes. Such findings would give clues for the possible biogenesis of the membrane-bound bodies from the epithelial cells. Such an origin is consistent with the idea that either all or part of the population of membrane-bound bodies is produced by a process of budding off from the basal cell membrane rather than by extension of an intracytoplasmic precursor through the plasma membrane