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. 2025 May 18;9(4):446–460. doi: 10.1093/evlett/qraf012

Figure 4.

Figure illustrating the molecular evolution of skeletal cell types, showing how the integration of functional gene modules contributed to cell type diversification and proposing a revised phylogenetic origin for hypertrophic chondrocytes.

The molecular evolution and origin of skeletal cell types. (A) Skeletal cell types diversification occurred through the recruitment of transcription factors and the integration of additional functional modules. We found that the implementation of genes modulating vasculogenesis and mitochondrion organization in OB and programmed cell death in HC contributed to the individuation of the ancestral IC expression program. (B) Simplified phylogenetic origin of skeletal cell types in animals. We suggest that endochondral ossification and HC evolved in the common ancestor of Chondrichthyes and Osteichthyes, moving the origin of HC from the ancestors of bony vertebrates.