SCO cells from old animals do not release SCO-Spondin under hyperglycemic conditions.

(A) Immunohistochemical staining of GLUT2, SCO-Spondin, acetylated α-tubulin, and vimentin in frontal brain sections from old hyperglycemic rats. Scale bar: 30 μm. (B) Immunohistochemical staining of vimentin of frontal brain sections containing ependymal cells from old hyperglycemic rats. Scale bar: 20 μm. (C) TEM analysis of SCO cells from hyperglycemic animals. ER and apSGs were abundant. Aggregated SCO-spondin that formed pre-RF was detected extracellularly (inset). No MVBs were observed. Scale bar: 10 μm; ER and apSGs, 2 μm. (D) TEM analysis of hyperglycemic SCO cells at high magnification. apSGs were observed in the apical region of cells with a lower content of blebs. Scale bar: 0.5 μm. (E) Ependymal cells did not show structural alterations; however, electrolucent areas were detected close to BVs, suggesting perivascular edema. No aggregate secretory material was observed to interact with the apex of ciliated cells, and MVBs were not observed. Scale bar: 5 μm; higher magnification, 2 μm. N = 3. apSG, apical secretory granule; BV, blood vessel; CSF, cerebrospinal fluid; ER, endoplasmic reticulum; MVB, multivesicular body; RF, Reissner’s fibers; SCO, subcommissural organ; TEM, transmission electron microscopy. (TIF)