Fig. 7

Representative transmission electron micrographs of A. pegreffii uterus formed by a basal lamina (bl) lined with a thick multicellular layer of sheath cells abundant in myofibril bundles. Note rare, scattered electron-dark mitochondria and more abundant electron-light granules. b Cuboid epithelial cells (in transverse section) with an electron-dense cytoplasm and microvilli localised on four cell edges interconnected in an intercellular space (white arrows). c Epithelial cells excreting electron-dense granules (putative vitellus) within the intercellular space. Note the different level of depletion of the granule content (white asterisk). d A layer of epithelial cells with labyrinth-like microvilli projecting in the uterus lumen (black asterisk). Note the three-leaf clover appearance of the prominent nucleolus (black arrowhead). e Apical periphery of the epithelial cell cytoplasm with electron-dark mitochondria (m) and intricate rough endoplasmic reticulum (white arrowheads). f Epithelial cell microvilli with a bilayer plasmalemma and electron-dense periphery. Scale bars: 5 µm (b); 2 µm (a, d); 1 µm (e); 500 nm (c); 200 nm (f)