Scanning electron micrograph of the epithelium of the human oviduct, at mid-cycle. The differences in size and shape of cilia and microvilli are well illustrated by scanning micrographs of the lumenal surface of the epithelium lining the mammalian oviduct. The tufts of cilia (here in pink) associated with individual ciliated cells project several microns above the convex apices of nonciliated cells covered with short microvilli (in sepia). The number of ciliated cells in this epithelium is under hormonal control by estrogens.