Abstract
Introduction: The epiphysis cartilage in the knee joint has been widely studied in recent decades
due to the joint complexity and its clinical importance. However, there is little
information about morphological and ultrastructural aspects of normal cartilage development
of the knee joint, particularly in human fetuses of different age, which could contribute
to a better understanding of diseases and malformations during development. Materials and Methods: This research was performed with 20 human fetuses covering the age range 16 to 31
weeks of intrauterine life, which were divided into 4 groups (n = 5). Morphometric
analysis of the distal femoral epiphysis cartilage were realized for the parameters:
chondrocytes area, percent density of chondrocyte and extracellular matrix (ECM),
as well as qualitative analysis of the distribution, organization and characterization
of collagen fibers making use of Picrosirius staining under analysis with polarized
light. Results: It was verified that the chondrocytes area and density of ECM increased with advancing
age, while the density of chondrocytes decreased. Also in the epiphyseal region, immature
cartilage of younger fetuses, initially with characteristics of a proliferation zone
starts to present, in older age fetuses, characteristics of a maturation zone, with
larger chondrocytes and more distant from each other. In the epiphysis surface the
organization and orientation of the collagen ibers changed in different groups, from
an irregular orientation in the younger fetuses group, to a pantograph organization
in the most developed fetuses group. Conclusion: During fetal development, the maturation of cartilage combines increasing ECM percent
density and changes in the collagen fibers organization and orientation, contributing
to the required cartilage properties for each stage of its development.
Keywords
articular cartilage - femur - fetuses - collagen
