RT Journal Article SR Electronic T1 Gap junction internalization and processing in vivo: a 3D immuno-electron microscopy study JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.06.29.178475 DO 10.1101/2020.06.29.178475 A1 Rachael P. Norris A1 Mark Terasaki YR 2020 UL http://biorxiv.org/content/early/2020/06/30/2020.06.29.178475.abstract AB Gap junctions have well-established roles in cell-cell communication by way of forming permeable intercellular channels. Less is understood about their internalization, which forms double membrane vesicles containing cytosol and membranes from another cell, called connexosomes or annular gap junctions. Here, we systematically studied the fate of connexosomes in intact ovarian follicles. High pressure frozen, serial sectioned tissue was immunogold labeled for Connexin 43. Within a volume of electron micrographs, every labeled structure was categorized and counted. Surface area measurements indicate that large connexosomes undergo fission. Subsequent modifications are separation of inner and outer membranes, loss of Cx43 from the outer membrane, and outward budding of the modified membranes. We also documented several clear examples of organelle transfer from one cell to another by gap junction internalization. We discuss how connexosome formation and processing may be a novel means for gap junctions to mediate cell-cell communication.Competing Interest StatementThe authors have declared no competing interest.