Simple cuboidal epithelium

In section the cells are about as tall as they are wide, each with a central, spherical nucleus, so the layer looks like a row of beads; in a duct or tubule cut transversely the cells form a ring around a lumen. They have more cytoplasm than squamous cells and are therefore suited to active transport and secretion.

In the proximal convoluted tubule the cells carry a prominent apical brush border (microvilli) and basal infoldings packed with mitochondria (basal striations) for reabsorbing ≈65 % of the filtered load; the distal tubule and collecting tubules are lined by cuboidal cells without a brush border. Thyroid follicles are lined by cuboidal follicular cells, which become flatter when inactive and taller when stimulated by TSH. The epithelium of the choroid plexus, the retinal pigment epithelium and the "germinal epithelium" (actually modified mesothelium) on the surface of the ovary are also simple cuboidal.