Figure 7.

Regional neurofilament accumulation and RT97 epitope levels are selectively and markedly reduced in Shiverer mutant mice. (A) Interneurofilament spacing in optic axons (700-μm level) of 3-month-old Shiverer mice (▴, shi) is similar to that of wild-type mice (○, wt). (B) Regional neurofilament accumulation (neurofilament number [700 μm − 50 μm/50 μm] × 100) was determined in >300 optic axons at the 50- and 700-μm levels for three wild-type or Shiverer homozygous mice. (C) SMI34, SMI31, and RT97 immunoreactivities as a ratio of total NFH (SMI33) immunoreactivity were determined in the same groups of mice by quantitative densitometry. All values are expressed relative to the wild-type control set at 100%. Each value represents the mean and standard error from four separate samples (*P < 0.05 and #P > 0.05 by Student's t test). Immunoelectron microscopy of the RT97 epitope in axons of normal and homozygous Shiverer mice. After incubation of treated epon sections with RT97 (see Materials and Methods), 5-nm gold-conjugated secondary antibody decorated neurofilaments in normal optic axons (not shown) and (D) Shiverer axons associated with primitive myelin sheaths (my; arrowhead). No RT97 immunoreactivity was detected in unmyelinated axons (unmy) from Shiverer mice.