Transmission electron microscope image of a thin section cut through the developing brain tissue (telencephalic hemisphere) of an 11.5 day mouse embryo. This image of the luminal surface of the telencephalon, shows junctional complexes and pinocytotic vesicles. The junctional complex is divided into three types of junctions: 1) the most apical is the tight junction, which controls and/or restricts the movement of molecules across epithelial layers and helps maintain polarity, 2) the zonula adherens, which also includes the numerous actin filaments seen in the apical cytoplasm, and 3) the desmosome, which is a spot junction. The pinocytotic vesicles are formed from coated pits in the plasma membrane and are involved in endocytosis.

JEOL 100CX TEM

References:

Marin-Padilla, M. (1985) "Early Vascularization of the Embryonic Cerebral Cortex: Golgi and Electron Microscope Studies", J. Comparative Neurology, 241:237-249