Figure 6.

Low dosage neuraminidase injection led to astrocyte incorporation similar to that found in aging. a, b, Colorized EM montages of the lateral walls 7 d (a) and 3 weeks (b) after a 10 ng neuraminidase treatment. An occasional astrocyte (arrowhead) was detected within the ependymal wall 7 d after treatment (a). In a representative section, three astrocytes (arrows in b) were found integrated within the ependymal lining by 3 weeks (b). c–e, These interposed astrocytes contained bundles of intermediate filaments (asterisks in c), formed adherens junctions with neighboring ependymal cells (arrowheads in d), and possessed basal bodies of cilia (arrows in e), demonstrating their similarity to astrocytes found in the elderly ependyma (see Fig. 1b,e–g). f, BrdU⁺/GFAP⁺/s100β⁺ cells were detected in the ependyma 5 weeks after 10 ng neuraminidase treatment and a 3 d BrdU injection paradigm. As, Astrocytes; E, ependymal cells; V, lateral ventricle.