Developmental morphometry of human articular cartilage: a comparative histological study across fetal stages and...

Articular cartilage is a highly specialized connective tissue with limited intrinsic regenerative capacity. Characterizing its developmental architecture is essential for understanding cartilage maturation and informing regenerative approaches. This study conducted histological and quantitative morphometric analyses of human fetal articular cartilage at 23, 27, and 36 weeks of gestation, using adult knee cartilage as a reference. Histological evaluation employed Hematoxylin and Eosin, Safranin O, Alcian Blue, Toluidine Blue, and Masson's trichrome staining, as well as collagen type II immunohistochemistry. Quantitative analysis with FIJI software measured cartilage thickness, area, zonal architecture, chondrocyte density, lacunar size, nuclear morphology, chondron organization, and matrix staining intensity. Results demonstrated progressive structural maturation across gestation, characterized by increased matrix deposition, changes in cellular organization, and emergence of zonal architecture. Fetal cartilage exhibited higher cellularity, larger lacunae, and increased proteoglycan staining, whereas adult cartilage showed reduced cellularity, matrix compaction, and well-defined zonal organisation. The tidemark was absent in fetal samples but clearly present in adult cartilage, indicating development of the calcified interface at later stages. Overall, these findings define the structural transition of human articular cartilage from a highly cellular, developmentally active tissue to a functionally specialized adult form. This developmental framework provides insight into cartilage histogenesis and a basis for designing regenerative strategies that recapitulate fetal-like properties.