A previous histological study in neonatal IH rats (Hong et al., 2021a) demonstrates that IH shifts proliferation and maturation in the mandibular condyle fibrocartilage toward hypertrophic differentiation and ossification by downregulating mRNA levels of SOX9 and TGF-β in male rats, which showed mandibular growth restriction. This evidence concerns the gene TGFB1 and isolated hemihyperplasia.