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Distribution of Cellular Proliferation in Skeletal Muscle Transverse Arterioles During Maturation
Author(s) -
PRICE RICHARD J.,
SKALAK THOMAS C.
Publication year - 1998
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1111/j.1549-8719.1998.tb00051.x
Subject(s) - skeletal muscle , distribution (mathematics) , transverse plane , anatomy , microbiology and biotechnology , chemistry , biophysics , biology , mathematics , mathematical analysis
Objective : To investigate the spatial and phenotypic origin of the new smooth muscle (SM) cells that are necessary for transverse arteriolar (TA) remodeling by establishing the distribution of cellular proliferation in TA trees during maturation. Methods : Whole‐mount gracilis muscles from rats at 4 and 9 weeks of age were immunolabeled for SM myosin heavy chain to denote arterioles and for bromodeoxyuridine to denote S‐phase (DNA synthesizing) nuclei. The dimensions of each clearly visible segment in TA trees were measured. S‐phase cells in the wall of, or within 5 µm of, TA segments were identified as (1) endothelium or intimal fibroblasts, (2) SM, or (3) interstitial cells. The relative percentages of each cell type in S‐phase, the distribution of arteriolar diameters containing S‐phase SM, and the density of S‐phase interstitial cells (per unit length and per unit surface area of TA) were determined. Alcian blue counterstaining was used to discern the percentage of interstitial cells that were mast cells. Results : At 4 and 9 weeks, respectively, 3.7% and 2.1% of S‐phase cells were endothelium or intimal fibroblasts, 3.0% and 4.2% were SM, and 93.3% and 93.7% were interstitial cells. No S‐phase interstitial cells within 5 µm of TAs were mast cells. The mean diameter of TA segments containing an S‐phase SM nucleus was 15.22 ± 1.2 µm at 4 weeks of age, with the minimum diameter being 8.9 µm. From 4 to 9 weeks of age, the number of interstitial cells per unit length of TA decreased 10‐fold from 15.2 ( n = 115) to 1.5 ( n = 182) cells/mm. At 4 weeks, the density of S‐phase interstitial cells was greatest surrounding the most terminal arterioles. Conclusions : When coupled with the result that S‐phase SM is absent in the most terminal segments, the relatively high density of S‐phase interstitial cells surrounding the smallest diameter terminal segments at 4 weeks of age is consistent with the hypothesis that fibroblast hyperplasia is a component of terminal arteriolar development.