Page 356 - Atlas of Histology with Functional Correlations

A section of the brain prepared by the Cajal method demonstrates the supportive

neuroglial cells called astrocytes. The fibrous astrocytes (2, 5) exhibit a small
cell body (5), a large oval nucleus (5), and a dark-stained nucleolus (5).
Extending from the cell body are long, thin, and smooth radiating processes (4,
6) found between the neurons and blood vessels. A perivascular fibrous
astrocyte (2) surrounds a capillary (8) with red blood cells (erythrocytes). From

other fibrous astrocytes (2, 5), the long processes (4, 6) extend to and terminate
on the capillary (8) as perivascular endfeet (3, 7).

Also seen in the illustration are nuclei of different neuroglial (1) cells of the
brain.

FIGURE 9.15 ■ Fibrous astrocytes and capillary in the brain. Stain: silver

impregnation (Cajal method). High magnification.

FIGURE 9.16 | Ultrastructure of CNS Capillary

and Perivascular Endfeet of Astrocytes

This transmission electron micrograph shows a cross section of a continuous
type of capillary in the CNS. Lining the capillary lumen is a thin endothelial
layer and the nucleus of an endothelial cell (2). Attached externally to the

capillary wall (5) are numerous perivascular endfeet of astrocytes (3, 4) that
completely envelop the capillary wall (5) to form part of the blood–brain barrier.
Surrounding the capillary wall (5) and the endfeet of astrocytes (3, 4) is the CNS
neuropil (1), a dense meshwork of fibers from axons, dendrites, and various
glial cells that fill the spaces in the CNS. Located below the capillary are

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