Figure 1.

Aged mice have a robust glial lamina that lacks ECM plates. (A–F) Optic nerves of 11–12-mo-old DBA/2J mice that do not develop glaucoma (D2-Gpnmb ⁺) were serially sectioned in longitudinal or cross-sectional planes. A robust astrocyte meshwork surrounds the axons where they exit the mouse eye. The astrocyte meshwork (glial lamina, delineated by brackets) is clearly evident as abundant nuclei oriented at right angles to the long axis of the optic nerve (A and B) and a cellular network (C and D, arrowheads) with extensive processes that stain positive for GFAP (E and F). In contrast to the lamina cribrosa of the human optic nerve (see Quigley and Addicks [1981]), the mouse astrocytes do not cover a network of robust collagenous plates (G and H). Although collagens are clearly visible in blood vessel walls (arrowheads), there is no meshwork of collagen staining that mirrors the astrocyte meshwork. All presented cross sections are from within the lamina region. V, vessels. Sections were stained with hematoxylin and eosin (H&E) (A and B, cells and axons pink; nuclei purple-blue); Bodian's stain (C and D, axons pale blue; nuclei dark purple-blue; glial cell bodies and processes remain clear); anti-GFAP with hematoxylin counter stain (E and F, astrocyte bodies and processes brown; nuclei purple-blue); or Masson's trichrome (G and H, collagens stain blue). Bars, 50 μm.