In this report the authors describe the structural and ultrastructural characteristics of some cells constituting the parietal layer of Bowman’s capsule of the mouse kidney, which are very similar to the epithelial cells of the proximal convoluted tubule (tubule-like cells). These elements are noted in mature and immature mice of both sexes, but their fine morphology and statistical incidence seem related to the sex and the age of the mice, as revealed by the different responsiveness of the same animals to sex hormones experimentally administered. Such substances, directly and/or through an influence on gonadotropins (especially luteinizing hormone), are able to modify (mainly increasing) the percentage of renal corpuscles possessing tubule-like cells.