Gender-specific distribution of glycosaminoglycans during cartilage mineralization of human thyroid cartilage

The role of glycosaminoglycans (GAG) in the process of cartilage mineralization, especially in the hypertrophic zone of growth plates, is not yet fully understood. Human thyroid cartilage can serve as a model to observe matrix changes associated with cartilage mineralization because the processes follow a distinct route, progress very slowly and show sexual differences. Histochemical staining for low sulphated GAG (chondroitin-4- and -6-sulphates) was decreased in the interterritorial matrix of thyroid cartilage starting at the beginning of the fifth decade, but not in the pericellular or territorial matrix of chondrocytes. Because cartilage mineralization progressed in the interterritorial matrix it seems likely that a decreasing content of chondroitin-4- and -6-sulphates is involved in the mineralization process. This hypothesis is supported by the observation that immunostaining for chondroitin-4- and -6-sulphates was weaker in mineralized cartilage areas than in unmineralized areas, whereas there was no difference in staining for keratan sulphate. In all life decades, female thyroid cartilages contained more chondrocytes with a territorial rim of chondroitin-4- and -6-sulphates probably preventing cartilage mineralization compared with age-matched male specimens. Taken together, the characteristic distribution pattern of chondroitin-4- and -6-sulphates being more concentrated in female than in male thyroid cartilages provided evidence that these macromolecules decrease in cartilage mineralization

Morphogenesis of the juxtaoral organ in humans

The juxtaoral organ was studied using light microscopy in 55 human embryos and 90 fetuses at different stages of development. The juxtaoral organ arises from the epithelium at the bottom of the transverse opening of the primitive mouth during O'Rahilly stage 16 and becomes detached from the epithelium after O'Rahilly stage 18. The juxtaoral organ is innervated by the buccal nerve from O'Rahilly stage 20 onward, and its connective tissue capsule is clearly visible after week 11 of development. This study enabled us to describe three main periods of juxtaoral organ development: (1) the period of epithelial condensation and invagination, at O'Rahilly stages 16–17; (2) the period during which the juxtaoral organ becomes detached from the oral epithelium and is innervated, at O'Rahilly stages 18–23; and (3) the period during which the connective tissue capsule is formed, after week 11 of development. We also analysed the juxtaoral organ of five additional fetuses by immunohistochemistry with anti-NF-200 to verify their innervation. The results show that the juxtaoral organ may have a function in the mechanical activity of the region