A Specialized Membrane Junction between Nerve Endings and B‐Cells in Islets of Langerhans

Abstract
The use of lanthanum as an extracellular tracer in isolated islets of Langerhans reveals zones of narrowing of the extracellular space (synaptic cleft) between nerve endings and B‐cells. These narrowed zones are interpreted as gap junctions and their presence shows that such endings have the morphological characteristics of both electrical and chemical synapses.