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The mesonephros of chick embryos from the 7th to the 15th day of incubation has been studied by scanning electron microscope. The material was submitted to the common techniques for scanning electron microscopy using a special fixing agent that does not damage the embryonic tissue (Litke e Low, 1977). At the 7th day of incubation, the mesonephric corpuscles show a capsule whose parietal lamina is formed by flattened cells, while the visceral lamina already shows podocytes provided with pedicels interdigitating around the capillary loops. In the same period the proximal tubules appear to be bounded by columnar cells with long and thick apical microvilli. The Henle's loop is lined by low cells with slightly dome-shaped apices provided with single cilium. The distal convoluted tubules are lined by a low columnar epithelium. The cell apices show microvilli shorter and more rare than those found in the proximal portion. This pattern is present till the 12th day of incubation, when regression phenomena occur. These are mainly represented by a progressive occlusion of the tubules and a gradual alteration of the podocytes.