Kardon G
DCMB Group, Duke University, LSRC Building, Research Drive Durham, NC 27708-1000, USA.
Development. 1998 Oct;125(20):4019-32. doi: 10.1242/dev.125.20.4019.
The proper development of the musculoskeletal system in the tetrapod limb requires the coordinated development of muscle, tendon and cartilage. This paper examines the morphogenesis of muscle and tendon in the developing avian hind limb. Based on a developmental series of embryos labeled with myosin and tenascin antibodies in whole mount, an integrative description of the temporal sequence and spatial pattern of muscle and tendon morphogenesis and their relationship to cartilage throughout the chick hind limb is presented for the first time. Anatomically distinct muscles arise by the progressive segregation of muscle: differentiated myotubes first appear as a pair of dorsal and ventral muscle masses; these masses subdivide into dorsal and ventral thigh, shank and foot muscle masses; and finally these six masses segregate into individual muscles. From their initial appearance, most myotubes are precisely oriented and their pattern presages the pattern of future, individual muscles. Anatomically distinct tendons emerge from three tendon primordia associated with the major joints of the limb. Contrary to previous reports, comparison of muscle and tendon reveals that much of their morphogenesis is temporally and spatially closely associated. To test whether reciprocal muscle-tendon interactions are necessary for correct muscle-tendon patterning or whether morphogenesis of each of these tissues is autonomous, two sets of experiments were conducted: (1) tendon development was examined in muscleless limbs produced by coelomic grafting of early limb buds and (2) muscle development was analyzed in limbs where tendon had been surgically altered. These experiments demonstrate that in the avian hind limb the initial morphogenetic events, formation of tendon primordia and initial differentiation of myogenic precursors, occur autonomously with respect to one another. However, later morphogenetic events, such as subdivision of muscle masses and segregation of tendon primordia into individual tendons, do require to various degrees reciprocal interactions between muscle and tendon. The dependence of these later morphogenetic events on tissue interactions differs between different proximodistal regions of the limb.
四足动物肢体中肌肉骨骼系统的正常发育需要肌肉、肌腱和软骨的协调发育。本文研究了发育中的鸟类后肢肌肉和肌腱的形态发生。基于一系列在整体标本中用肌球蛋白和腱生蛋白抗体标记的胚胎发育序列，首次对整个鸡后肢肌肉和肌腱形态发生的时间顺序和空间模式及其与软骨的关系进行了综合描述。解剖学上不同的肌肉通过肌肉的逐步分离而产生：分化的肌管最初表现为一对背侧和腹侧肌肉块；这些肌肉块再细分为大腿背侧和腹侧、小腿和足部肌肉块；最后这六个肌肉块分离成单个肌肉。从最初出现开始，大多数肌管就精确地定向，其模式预示着未来单个肌肉的模式。解剖学上不同的肌腱从与肢体主要关节相关的三个肌腱原基中产生。与之前的报道相反，肌肉和肌腱的比较表明，它们的大部分形态发生在时间和空间上紧密相关。为了测试肌肉-肌腱相互作用对于正确的肌肉-肌腱模式形成是否必要，或者这些组织中的每一个的形态发生是否是自主的，进行了两组实验：（1）通过早期肢芽的体腔移植产生的无肌肉肢体中肌腱发育的研究，以及（2）对肌腱已通过手术改变的肢体中肌肉发育的分析。这些实验表明，在鸟类后肢中，最初的形态发生事件，即肌腱原基的形成和肌源性前体细胞的初始分化，彼此独立发生。然而，后来的形态发生事件，如肌肉块的细分和肌腱原基分离成单个肌腱，则在不同程度上需要肌肉和肌腱之间的相互作用。这些后期形态发生事件对组织相互作用的依赖性在肢体的不同近端-远端区域有所不同。
