Mozdziak P E, Schultz E, Cassens R G
Department of Meat and Animal Science, University of Wisconsin, Madison 53706.
Poult Sci. 1994 Apr;73(4):547-55. doi: 10.3382/ps.0730547.
The relationship between satellite cell mitotic activity and skeletal myofiber growth was examined in Pectoralis thoracicus and Biceps femoris muscles of Large White tom turkeys (Nicholas strain) at 3, 6, 9, 18, and 26 wk of age. Mitotically active satellite cells were labeled with 5-bromo-2'-deoxyuridine (BrdU). Labeled satellite cells were identified on enzymatically isolated myofiber segments using mouse anti-BrdU followed by fluorescein-5-isothiocyanate (FITC) conjugated goat anti-mouse IgG secondary antibodies. Myofiber nuclei (satellite cell nuclei + myonuclei) were counterstained with propidium iodide (PI). Myofiber segment diameter, myofiber segment length, and number of FITC- and PI-labeled nuclei were determined for each segment. At each age interval there was an increase in myofiber diameter, suggesting that the myofibers were growing during the entire experimental period. There was an age-related (P < .001) decrease in satellite cell mitotic activity and an age-related increase (P < .001) in the cytoplasmic volume to nucleus ratio (CNR) from 3 to 26 wk of age. An early phase of myofiber growth, between 3 and 6 wk of age, was characterized by a high level of satellite cell mitotic activity and increased CNR. Between 6 and 9 wk of age, satellite cell mitotic activity decreased, but the CNR showed no change (P > .05). During a late phase of myofiber growth, beyond 9 wk of age, satellite cell mitotic activity continued to decrease and myofiber growth occurred by an increased CNR. This study demonstrated that both Pectoralis thoracicus and Biceps femoris undergo a significant late phase of growth without appreciable production of myonuclei by satellite cell proliferation.
研究了3、6、9、18和26周龄的大白公火鸡（尼古拉斯品系）胸大肌和股二头肌中卫星细胞有丝分裂活性与骨骼肌纤维生长之间的关系。用5-溴-2'-脱氧尿苷（BrdU）标记有丝分裂活跃的卫星细胞。使用小鼠抗BrdU，然后用异硫氰酸荧光素（FITC）偶联的山羊抗小鼠IgG二抗，在酶分离的肌纤维片段上鉴定标记的卫星细胞。用碘化丙啶（PI）对肌纤维细胞核（卫星细胞核+肌细胞核）进行复染。测定每个片段的肌纤维片段直径、肌纤维片段长度以及FITC和PI标记的细胞核数量。在每个年龄间隔，肌纤维直径都有所增加，这表明在整个实验期间肌纤维都在生长。从3周到26周龄，卫星细胞有丝分裂活性呈年龄相关下降（P<0.001），细胞质体积与细胞核比率（CNR）呈年龄相关增加（P<0.001）。在3至6周龄的肌纤维生长早期阶段，其特征是卫星细胞有丝分裂活性高且CNR增加。在6至9周龄之间，卫星细胞有丝分裂活性下降，但CNR没有变化（P>0.05）。在9周龄以后的肌纤维生长后期，卫星细胞有丝分裂活性继续下降，肌纤维生长通过增加CNR来实现。本研究表明，胸大肌和股二头肌在生长后期都经历了显著的生长阶段，而卫星细胞增殖并没有明显产生肌细胞核。
