Nervous System

Brain - Microgliosis

    Microgliosis adjacent to an inflammatory mononuclear perivascular cuff (arrow) in a female F344/N rat from a chronic study. Note the many elongated, irregular nuclei of typical microglial cells.
    Nuclei of microglia at a higher magnification in a female F344/N rat from a chronic study. Their elongated irregular nuclear morphology (arrows) is apparent.
    A particularly useful immunohistochemical stain using the Iba-1 antibody to detect these cells (arrows) in the brain in an F344/N rat. Other immunohistochemical methods used as microglial markers include OX-42 and CD68.
    Reactive gliosis and capillary hyperplasia (arrow) in a site of former injury in a female F344/N rat from a chronic study. Capillaries are quickly responsive to injury of adjacent tissue, and endothelial nuclear hypertrophy is evident within 24 hours.
    A mixed gliotic response to injury of the putamen, consisting of reactive astrocytes, macrophages, microglia, and mononuclear cells, in a male B6C3F1 mouse from a chronic study. It is apparent that there is a significant increase in nucleated cells in the region.
    Reactive gemistocytic astrocytosis in a site of healing neural injury stained with hematoxylin and eosin, in a treated female F344/N rat from a chronic study. Note the typical eccentric nucleus and prominent eosinophilic cytoplasm of these reactive astrocytes (arrowheads) and the less frequent micro-binucleate form (arrow).


    Peter Little, DVM, MS, PhD, DACVP
    Neuropathology Consultant
    Experimental Pathology Laboratories, Inc.  
    Research Triangle Park, NC

    Deepa B. Rao, BVSc, MS, PhD, DABT, DACVP
    NTP Pathologist (Contractor)
    Integrated Laboratory Systems, Inc.
    Research Triangle Park, NC


    James P. Morrison, DVM, DACVP
    Scientific Director
    Charles River Laboratories, Pathology Associates
    Research Triangle Park, NC

    Robert C. Sills, DVM, PhD, FIATP
    Chief, Cellular and Molecular Pathology Branch
    National Toxicology Program
    National Institute of Environmental Health Sciences
    Research Triangle Park, NC