Neuronal and oligodendrocytic response to cortical injury: ultrastructural and cytochemical changes

Ultrastructural Pathology of Oligodendroglial Cells in Traumatic and Hydrocephalic Human Brain Edema: A Review

Oligodendroglial cell changes in human traumatic brain injuries and hydrocephalus have been reviewed and compared with experimental brain edema. Resting unreactive oligodendrocytes, reactive oligodendrocytes, anoxic-ischemic oligodendrocytes, hyperthrophic phagocytic oligodendrocytes, and apoptotic oligodendrocytes are found. Anoxic-ischemic oligodendrocytes exhibit enlargement of endoplasmic reticulum, Golgi complex, and enlargement and disassembly of nuclear envelope. They appear in contact with degenerated myelinated axons. Hypertrophic phagocytic oligodendrocytes engulf degenerated myelinated axons exerting myelinolytic effects. A continuum oncotic and apoptotic cell death type leading to necrosis is observed. The vasogenic and cytotoxic components of brain edema are discussed in relation to oligodendroglial cell changes and reactivity.

Ultrastructural study on meningeal regeneration and meningo-glial relationships after cerebral stab wound in the adult rat

Meningeal regeneration and meninges-glial relationships during the reparation of an experimental brain stab wound, are studied with the electron microscope. At 14 days after the wound, a continuous newly formed basal lamina separates both nervous and meningeal tissues. Later, the astroglial processes of regenerated glia limitans showed very infolded surfaces and numerous filaments inside of them. Across the cavity left by the wound, filament-rich astroglial processes, forming bundles or glial cords of variable diameter, were seen. Each glial cord was surrounded by a basal lamina covered on the outside by a discontinuous sheet of meningocytic processes. Although regenerated meningocytes displayed interlacing processes forming a loose reticular network, large cellular meningocyte masses were also found.

Ultrastructural study of phagocytic activities of young astrocytes in injured neonatal rat brain following intracerebral injection of colloidal carbon

The cellular reaction to injury in the mature central nervous system (CNS) has been extensively studied in both man and animals, while a detailed study of the reaction of the immature CNS to injury is lacking in the literature. This study was undertaken to elucidate the response of young astrocytes following injection injury to developing brain. Colloidal carbon was applied because it is a suitable marker for phagocytosis, it is nontoxic, and it is readily identifiable by light and electron microscopy. The cerebral cortex of the neonatal rat was injected with 0.1 microliter of colloidal carbon solution. The animals were allowed to survive from 1 hour to 30 days postoperation. The brains were fixed by vascular perfusion and processed for light and electron microscopy. Carbon particles were ingested in membrane-bound vacuoles and sequestered in lysosomes of young astrocytes. Astrocytes, loaded with carbon particles, were identified after 4 days, and were seen in abundance between 10 to 21 days postoperation. Carbon-laden astrocytes were seen in the immediate vicinity of the site of the injection; in the surrounding, apparently normal, neuropil; and in the perivascular regions. This study demonstrates the ability of young astrocytes to engulf foreign particles injected into the developing brain. The presence of carbon particles in astrocytes located further away from the site of injection is discussed.