ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
The differentiation of fiber type characteristics in the anterior (ALD) and posterior (PLD) latissimus dorsi muscles is examined by the freezefracture technique in 1-, 7- and 30-day-old chicks. Several characteristics of plasma membrane (caveolae, rectilinear arrays, intramembranous particles) and sarcoplasmic reticulum which show fiber type differences in the adult ALD and PLD muscles are compared in the developmental stages. The caveolar density in the ALD fibers is about 20/μm2 at 1 day increasing to about 37/μm2 at 30 days, whereas in the PLD fibers it remains at about 20/μm2 during this period. The distribution of the caveolae in the two muscles is different from the begining; in the ALD fibers the caveolae are distributed throughout the plasma membrane and in PLD fibers they are patterned into clusters overlying the I band regions. The density of intramembranous particles of 1-day ALD and PLD plasma membranes appears similar, but by 7 days the particle counts in the sarcolemma of the ALD muscle are about twice as numerous as those in the PLD muscle. The rectilinear arrays are virtually absent in the ALD muscle, whereas in the PLD muscle their density is about 10/μm2 at 1 day and about 20/μm2 at 7 days. Already at 1 day posthatching the SR in ALD and PLD fibers has the adult configuration, i.e., an open irregular network in ALD fibers and periodically arranged tubules with triadic expansions in the PLD fibers. It is concluded that the membrane structure of ALD and PLD muscles is already different at hatching, and at 1 week the differences are identical to those of slow and fast fibers of the adult stage. The membrane changes, therefore, do not support the view that the ALD muscle undergoes a transitional, fast-type stage in posthatching chicks.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1051830203
