title: Fine structural correlates of vascular permeability of chromaffin cell transplants in CNS pain modulatory regions.
abstract: Adrenal medullary tissue, bovine chromaffin cells, and PC12 cells were transplanted into the pain modulatory regions of the rat midbrain periaqueductal gray (PAG) or dorsal spinal cord. Fine structural studies of vascular permeability of these grafts revealed that in all three cases, the capillary endothelium of the graft vasculature was attenuated and fenestrated, unlike that of the surrounding host CNS tissue. The intravascular injection of the protein marker, horseradish peroxidase (HRP), enters the grafted tissue parenchyma and is found in the extracellular space of the surrounding host CNS. In contrast, control gelfoam transplants, which become vascularized, do not contain vessels with fenestrated endothelium and do not leak HRP. Since cell suspension implants do not contain endothelial cells, the vasculature of the grafts must be derived from the host. However, as their morphological characteristics are similar to those of the in situ adrenal medulla, it appears that the tissue environment of the graft influences the permeability properties of the vascular bed. The increased permeability to HRP is apparently permanent and most likely is due to the passage through endothelial cell fenestrae.
authors.affiliation: Department of Anatomy and Cell Biology, University of Illinois, Chicago 60680.
authors.forename: G D
authors.initials: GD
authors.lastname: Pappas
authors.forename: J
authors.initials: J
authors.lastname: Sagen
mesh_terms: D000313:Adrenal Medulla / Q000098:blood supply* / Q000166:cytology / Q000637:transplantation / Q000648:ultrastructure; D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000502:physiology / Q000648:ultrastructure; D002199:Capillary Permeability; D002417:Cattle; D002838:Chromaffin System / Q000098:blood supply* / Q000166:cytology / Q000637:transplantation / Q000648:ultrastructure; D006735:Horseradish Peroxidase; D008854:Microscopy, Electron; D010146:Pain; D051381:Rats; D011919:Rats, Inbred Strains; D014407:Tumor Cells, Cultured / Q000637:transplantation / Q000648:ultrastructure
chemical_list: D006735:Horseradish Peroxidase