The morphology of the sensory nerve endings of lower lip mucosa was studied using transmission electron microscopy. The sensory nerve endings are constituted by several thin terminal axons ranging from O.25 to 1.5 mum, and each one is somrrounded by cytoplasmic processes of lamellar cells. These lamellae measure approximately 0.l5mum in width, and contain rough endoplasmic reticulum, mitochondria, microfilaments, and caveolae. Between the lamellae and the terminal axons and also the adjacent lamella are noted desmosome-type junctions. The terminal axons contain numerous mitochondria and clear vesicles measuring from 30 to 5Onm in diameter. The basal lamina of lamellar processes is generally extense appearing as several electron dense lines, and the interlamellar space is characterized by an amorphous substance and some fine collagen fibrils.