Research Interests
Roger C. Wagner, Ph.D.
Professor of Biological Sciences
University of Delaware
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     The focus of my research is the role of pericytes and endothelial cells in the function of microvessels and capillaries. Electron-dense tracers have been used to determine the paracellular (endothelial junctions) and transcellular (endothelial vesicular system) pathways across the endothelium of blood capillaries in the eel rete mirabile. Electron energy loss spectroscopy has been utilized to detect different elemental tracers perfused in timed intervals and their location in pathways in temporal sequences. Computerized reconstruction of images of ultrathin serial sections through the capillary wall reveals that the vesicular system is comprised of conjoined membraneous compartments which connect to both endothelial surfaces. Electron-dense tracers used in conjunction with thin serial section reconstruction has revealed that the vesicular system transports solutes across the capillary wall. Freeze-fracture studies indicate that rete capillary endothelial cells are joined by linear low-resistence gap junctions flanked on both sides by tight junctional assemblies. This implies ionic communication between the endothelial cells as well as occlusion of solute transport through the paracellular route.

          Pericytes which encircle capillaries may regulate blood flow via their contraction. They may also modulate capillary permeability by changing the amount of capillary wall they cover. Pericytes cultured from isolated rete capillaries contract and attenuate in response to vasoactive agents. Scanning electron microscopy has revealed that rete capillary pericytes in situ are connected by their processes into a syncytium. This cytoplasmic continuum implies coordination of pericyte contraction as well as mitotic activity.

Recent Publications:

         Chen, Shih-Chieh, Liu, Keh-Min and Wagner, R. C. 1998. Three-Dimensional
       Analysis of Vacuoles and Surface Invaginations of Capillary Endothelia in the
       Eel Rete Mirabile. Anatomical Rec. 252: 546-553.

     Wagner, R. C. and Kachar, B. 1995. Linear Gap and Tight Junctional Assemblies
       between Capillary Endothelial Cells in the Eel Rete Mirabile. Anatomical Rec.
      242: 344-352.

      Murphy, D. D. and Wagner, R. C. 1994. Differential Contractile Response of
      Cultured Microvascular Pericytes to Vasoactive Agents. Microcirculation 1:

   Wagner, R. C. and Hossler, F. E. 1992. SEM of Capillary Pericytes prepared by
        Ultrasonic Microdissection: Evidence for the Existence of a Pericapillary
        Syncytium. Anatomical Rec. 234: 249-254.

    Wagner, R. C. and Chen, S. C. 1991. Transcapillary Transport of Solute by the
        Endothelial Vesicular System: Evidence from Thin Serial Section Aanalysis.
        Microvascular Res. 42: 139-150.