Intermuscular bone (IB) is a hard-boned spicule exist in lower teleost, which brings a lot of detrimental effects on palatability and economic value of blunt snout bream (Megalobrama amblycephala). Masson trichrome staining for ossific IB indicated that some osteoblasts appeared at the edge of the bone matrix and a few osteocytes are present in the center of the mineralized bone matrix. By comparing the orthologous gene families of fish with IBs and without IBs, we screened the key signaling pathways associated with IB formation. Furthermore, the transcriptomic data demonstrated the functional importance of these gene families. The candidate genes involved in chondrocyte development were highly expressed in stage 1 compared with stage 2 and stage 3, suggesting that the development process of IB might mainly involve in intramembranous ossification. Our research reveals the molecular mechanism of IBs formation, and provides molecular evidence for the further study on intermuscular boneless stains.

肌间骨（IB）是一种硬骨骨刺，存在于下层硬骨中，对钝头鲷（ Megalobrama amblycephala）的适口性和经济价值带来很大的不利影响。）。骨化IB的Masson三色染色表明一些成骨细胞出现在骨基质的边缘，并且一些骨细胞存在于矿化骨基质的中心。通过比较具有 IB 和没有 IB 的鱼类的直系同源基因家族，我们筛选了与 IB 形成相关的关键信号通路。此外，转录组数据证明了这些基因家族的功能重要性。参与软骨细胞发育的候选基因在第1阶段与第2阶段和第3阶段相比高表达，表明IB的发育过程可能主要涉及膜内骨化。我们的研究揭示了IBs形成的分子机制，为进一步研究肌间无骨染色提供了分子证据。