Fig. 3. Delayed nerve regeneration in the sciatic nerves of GFAP-null mice revealed by morphologic and morphometric analysis. (A-F) Light-microscopy images of injured nerves of GFAP-null mice, 3 mm distal to the lesion, compared with age-matched controls at different time points. Electron microscopy images of t10 (ten days after crushing) nerve samples are shown in (A¹) for control and (B^I,B^II) for mutant mice. Ten days after crushing, nerves of control mice showed several fibers in 1:1 ratio as well as thinly myelinated fibers (A,A^I), whereas in nerves of mutant mice Schwann cells prevailed that were still sorting axons (B,B^I) and bands of Bungner (B^II). Twenty-one days after crushing, maturation of nerves in control mice was evident (C) whereas nerves of mutant mice still showed several degenerating fibers and clusters of regeneration (D). Forty-five days after crush, nerves of controls were nearly normal (E) whereas nerves of GFAP-null mice contained degenerating and thinly myelinated fibers (F). (G-N) Morphometric analysis of regenerating nerves at different time points, comparing data obtained 3 mm and 10 mm distally to the site of injury. (G,H) Diagram of the total number of fibers at 10, 21 and 45 days after injury; nerves of GFAP-null mice always showed significantly reduced number of fibers. (J-N) Diagram of the regenerating nerves at different time points subdivided per fiber diameter; results show reduced number of regenerating fibers in nerves of mutant mice, primarily those with larger diameter. Error bars represent the +s.e.m. Bar in F, 10 µm for A-F; 6 µm for A^I; 3 µm for B^I,B^II. ^*P<0.05.