Morphology and Anatomic Distribution

Of Astrocytes The interstitial tissue between neurons and blood vessels which contain stellate and spindle-shaped cells was named as neuroglia or nerve glue by Virchow in 1860 (2). About 100 years ago, use of the gold sublimate staining method showed well-developed processes to emerge from many sides of astrocytes giving them their stellate shape and allowing the distinction of astrocytes from other glia (3). Cajal also noted that the tips of astrocytic processes having bulbous dilatations or...

Notes

BBBD requires general anesthesia for a number of reasons (3, 4, 6). The procedure generates a significant level of pain. It causes a transient rise in intracranial pressure requiring cerebral protection. An actual increase in brain water (vasogenic edema) of 1-1.5 has also been documented after the procedure. 2. Propofol has been shown to be the most efficient agent, producing greater than 95 of good to excellent BBBD in animals (19). With increase in both the consistency and the intensity of...

Endothelial Mechanisms in Vasogenic Edema

Vasogenic edema is the endpoint of many acute neurological disorders as described in the preceding section and is characterized by BBB breakdown to plasma proteins. Progressive brain swelling due to the edema leads to cerebral herniations and death, hence the importance of this condition. 5.1. Experimental Permeability of the BBB to plasma proteins is best studied using Models an in vivo model since cultured brain endothelial cells do not develop junctions having the same degree of tightness as...

Marie Blanchette and David Fortin Abstract

Standard chemotherapy administered systemically has a limited efficacy in the treatment of brain tumors. One of the major obstacles in the treatment of brain neoplasias is the impediment to delivery across the intact blood-brain barrier (BBB). Many innovative approaches have been developed to circumvent this obstacle. One such strategy is BBB disruption (BBBD), which successfully increases the delivery of antineoplastic agents to the central nervous system (CNS). This chapter describes the...

Structural Components of the BNB

The BNB delimits the endoneurial microenvironment of the peripheral nervous system (PNS), a space that extends from the proximal root attachment zones of cranial and spinal nerves to the distal sensory and motor end-organs. Numerous studies in a variety of species, including rats, mice, rabbits, cats, dogs, humans, and frogs have demonstrated that nerve fascicles and the endoneur-ial compartment therein are anatomically circumscribed by a connective tissue ensheathment within which and through...

Factors Regulating BNB Permeability

Microvessels in the endoneurium are the least permeable capillaries except for intracerebral capillaries. The investing perineu-rium is even less permeable than the endoneurial capillaries. Hence, cellular components of the endoneurium secrete soluble factors responsible for maintaining the integrity of the tight junc-tional complexes and associated actin cytoskeletal components of endoneurial vascular endothelial cells and of cells composing the innermost layers of the perineurium. It should...

Pericytes and Disease

As discussed above, pericytes play an important role in the maintenance of vascular and tissue homeostasis and are integral to injury responses. Under normal conditions the pericyte is relatively quiescent and is essential for vascular stability. Under conditions of stress or injury, the pericyte undergoes phenotypic and functional changes that may include migration, proliferation or differentiation. How these events that include pericyte reprogramming are coordinated at the molecular level...

Endoneurial Homeostasis

The Controlled Variables of Endoneurial Homeostasis 5.2. Endoneurial Homeostasis During Development The various compartments of the nervous system employ homeo-static mechanisms to regulate their respective internal environments. The relevant physiological functional unit for a vertebrate peripheral nerve is a fasciculus, the cylindrical structural entity encompassing axons, glial cells, and other attendant satellite cells that is defined by the perineurium. The physical limit of the...

Morphology

Central Nervous In the mature CNS capillary, the pericyte is located between the System (CNS) Pericyte EC and parenchymal astrocytes and neurons (Fig. 1). Pericytes Morphology have a prominent round nucleus that clearly differs from the elon gated cigar shaped nucleus of the EC. The pericyte extends long Fig. 1. Cross section of a CNS capillary is shown in cartoon form. The pericyte is located between the endothelial cells (EC) and astrocytes (not shown). Pericyte projections (white) wrap...

Acknowledgments

Cynthia Hawkins and Dittkavi S.R. Sarma for reviewing this manuscript and for their helpful suggestions. 1. Parpura V, Haydon PG (2009) Astrocytes in (Patho) Physiology of the Nervous System. Springer Science + Business Media, New York 2. Virchow R (1860) Cellular Pathology. Churchill, London 3. Cajal SR (1913) Sobre un neuvo proceder de impregnacion de la neuriglia y sus resultados en los centros nerviosos del hombre y animales. Trab lab Invest Biol Univ Madr 11...

Endoneurial Fluid Dynamics

Continuity Between CSF and Endoneurial Fluid The extracellular space within a nerve fascicle is about 20-25 of the total intrafascicular volume. The endoneurial hydrostatic pressure (EHP) exerted by this fluid is about 2-3 mmHg. In terms of fluid dynamics, the endoneurial contents consist of a noncom-pressible aqueous solution, and a somewhat compressible cellular content constrained by an elastic sheath, the perineurium. Hence, the EHP will be determined by the volume of the endoneurial...