ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The distribution and typology of fibers in the two muscular systems (sphincter and dilator) of the iris in Gallus gallus were determined histochemically, immunohistochemically, and ultrastructurally. The sphincter muscle in proximity to the ciliary margin was composed predominantly of slow fibers. In the intermediate tract, a large group of fast oxidative fibers were evident and the pupillary margin was exclusively composed of slow fibers. The fast-fibers had histochemical and immunohistochemical patterns similar to the α fibers in the skeletal control muscle (biventer cervicis). In contrast, the slow fibers were composed of at least three slow types, which were comparable to the isoforms of the different myosins in β1 and β2 skeletal fibers.In the dilator muscle, the oblique system was uniquely composed of fast oxidative fibers. The radial system was predominantly composed of slow fibers with isoforms of myosins different from the slow fibers of the sphincter and control muscles.Ultrastructural features (width of Z bands, extension of the sarcoplasmic reticulum and SR-T tubule junctions, and number of mitochondria) confirm the histochemical and immunohistochemical assessments of fiber types, even if some peculiar aspects in several fibers were observed. Smooth muscle cells separated from striated fibers were evident at the pupillary margin. The hypothesis of a mesenchymal origin for all irideal striated muscles is discussed.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1092210303
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