Jr. Torrella et al., INNERVATION DISTRIBUTION PATTERN, NERVE ENDING STRUCTURE, AND FIBER TYPES IN PIGEON SKELETAL-MUSCLE, The Anatomical record, 237(2), 1993, pp. 178-186
Four fiber types have been characterized in different pigeon skeletal
muscles according to their innervation pattern (nerve ending structure
and innervation distribution) and histochemical properties (SDH and m
-ATPase activities). All fast fibers, types IIA and IIB, present aggre
gated distribution of their nerve endings with ''en plaque'' structure
s and very low innervation frequencies. The two kinds of slow fibers r
ecognized are multiple innervated and present higher innervation frequ
encies. However, type I fibers have nerve terminals in small knobs wit
h uniform localization, whereas type III fibers present ''en grappe''
nerve endings, which tend to be randomly distributed. Fiber type compo
sition of skeletal muscles has been found closely related, to their bi
omechanical function. Fast fibers are predominant in muscles with an a
ctive role in locomotive movements, whereas slow fibers are mainly or
exclusively located in postural muscles. (C) 1993 Wiley-Liss, Inc.