Figure 3

Stage of metanephridial system development in Lepidochitona corrugata (spm 4). A. Posterior part from dorsal with transparent external surface and planes (ortho slices) of section images shown in B-O. B, E, H, K, N. Total LM cross sections through the anlagen of the metanephridial and pericard/heart complex with stippled rectangles indicating the position of details given in the TEM sections C, D, F, G, I, J, L, M, O. C. Right side of the anlage with early lateral primordium of the kidney (enlarged in D). F. Right side of the anlage slightly further posterior than C, dorsal differentiation enlarged in G. I. Right side of the anlage slightly further posterior than F, dorsal dense tissue enlarged in J. L, M, O. Posterior portion of the anlage. aj, adhaerens junction; dgl, digestive gland; ep, epidermis; f, foot; i, intestine; lap, lumen of the anlage of pericardium and heart; mc, mitotic cells; mf, muscle fibers; mi, mitochondria; nd, nephridial differentiation; nu, nucleus; pc, primary body cavity; r, rectum; rln, right lateral nerve cord.