Lewandowski Damian, Dubińska-Magiera Magda, Migocka-Patrzałek Marta, Mazan Sylvie, Daczewska Małgorzata
Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, Wroclaw 50-335, Poland.
Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, Wroclaw 50-335, Poland.
Micron. 2025 Sep;196-197:103865. doi: 10.1016/j.micron.2025.103865. Epub 2025 Jun 13.
We report here a study of early trunk muscle differentiation in the catshark S. canicula, a representative of Chondrichthyes. Light and TEM investigations revealed that during S. canicula somitogenesis, the metameric cell segments (somites) are formed and their cell arrangement resembles the shape of a rosette. The somite structure shares similarities with those observed in lungfish and urodeles. As embryogenesis proceeds, somites differentiate into three compartments: the dermomyotome (with dorsomedial and ventrolateral lips), myotome, and sclerotome. In the developing myotome two, morphologically different classes of cells are distinguished: elongated cells with homogenous nuclei and bottle-shaped cells with condensed nuclei. Based on morphological studies, we hypothesize that in S. canicula, the second class of cells observed in the early myotome can be classified as muscle progenitor cells. Myogenesis in small-spotted catshark starts in the ventral part of the somite, as observed for the development of trunk muscles in teleosts. In summary, the structure of somites in S. canicula shares similarities with lungfish and urodeles, which could reflect plesiomorphic features of small-spotted catshark myogenesis. On the other hand, the myogenesis appear to be apomorphic feature. Many issues related to myogenesis in sharks, cartilaginous fish representatives, remain unresolved. These data provide new insights into myogenesis in Chondrichthyes, the closest outgroup to Osteichthyes, and contribute to a better understanding of ancestral features of this process and its diversification across vertebrates.
我们在此报告一项对猫鲨（Scyliorhinus canicula，软骨鱼类的代表物种）早期躯干肌肉分化的研究。光学显微镜和透射电子显微镜研究表明，在猫鲨体节发生过程中，分节的细胞段（体节）形成，其细胞排列类似于玫瑰花结的形状。体节结构与在肺鱼和有尾两栖类中观察到的结构有相似之处。随着胚胎发育的进行，体节分化为三个部分：皮肌节（有背内侧和腹外侧唇）、肌节和生骨节。在发育中的肌节中，可以区分出两类形态不同的细胞：具有均匀细胞核的细长细胞和具有浓缩细胞核的瓶状细胞。基于形态学研究，我们推测在猫鲨中，早期肌节中观察到的第二类细胞可归类为肌肉祖细胞。小斑猫鲨的肌发生始于体节的腹侧部分，这与硬骨鱼类躯干肌肉的发育情况一致。总之，猫鲨体节的结构与肺鱼和有尾两栖类有相似之处，这可能反映了小斑猫鲨肌发生的原始特征。另一方面，肌发生似乎是一种衍生特征。许多与鲨鱼（软骨鱼类代表）肌发生相关的问题仍未解决。这些数据为硬骨鱼类最接近的外类群软骨鱼类的肌发生提供了新的见解，并有助于更好地理解这一过程的祖先特征及其在脊椎动物中的多样化。
