Longitudinal pathologic study of the gastrocnemius muscle group in mdx mice.
Muscle necrosis in mdx mice is rare before the 2nd week of life, but becomes pronounced from weeks 2 to 6. There is no agreement on what happens after this age. Using sequential microscopic histology, immunohistochemistry and histomorphometry, we studied the evolution of muscle pathology throughout the mdx life span. Between 2 weeks and 3 months, multiple necrotic groups involving variable numbers of fibres were observed in the same section. During this period, most necrotic groups comprised more than 15 fibres. From 3 to 6 months, necrosis diminished progressively, involving isolated fibres or groups of two to five fibres, and most fibres had a centrally located nucleus. From 6 months onward there was progressive variation of fibre size and deposition of fibrillary collagens. Mast cell counts increased progressively until 6 months of age. Diminishing necrosis rather than increasing regeneration may explain the differences in muscle pathology observed between human DMD and mouse mdx. Mast cells play a secondary role in pathogenesis.
Roig
Manuel
M
Secció Neurologia Infantil, Hospital Universitari Vall d'Hebron, Passeig Vall d' Hebron 119-129, 08035, Barcelona, Spain. manroig@ cs.vhebron.es
Roma
Josep
J
Fargas
Arnau
A
Munell
Francina
F
D000818:Animals; D002452:Cell Count; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008407:Mast Cells / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D018485:Muscle Fibers, Skeletal / Q000473:pathology*; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology; D009336:Necrosis; D012038:Regeneration