Temporal and spatial localization of type I and II collagens in human thyroid cartilage

Cyst-like change in the thyroid cartilage: A developmental variant in children

Neck sonography is frequently encountered on ultrasound lists in the paediatric patient population. Anecdotally, one of the most frequent clinical indications is the investigation of a neck lump. While performing an ultrasound of the neck, structures other than those routinely assessed, such as the thyroid cartilage and mandibular cortex also come into view. Occasionally, pathology in these structures is also encountered, albeit less frequently. The purpose of this case report and review is to illustrate the ultrasound, computed tomography and magnetic resonance imaging appearances of cyst-like changes in the thyroid cartilage that are encountered in children, particularly in early adolescence.

Localization of type I and II collagen during development of human first rib cartilage

The localization of fibrillar type I and II collagen was investigated by immunofluorescence staining with specific antibodies in order to obtain a better understanding of tissue remodelling during the development of first rib cartilage. In childhood and early adolescence type I collagen was found to be restricted to the perichondrium of first rib cartilage, while type II collagen was localized in the matrix of hyaline cartilage. However, in advanced age type I collagen was also found in the territorial matrix of intermediate and central chondrocytes of first rib cartilage. The matrix of subperichondrial chondrocytes was negative for type I collagen. This suggests that some chondrocytes in first rib cartilage undergo a modulation to type I collagen-producing cells. The first bone formation was observed in rib cartilages of 20- to 25-year-old adults. Interestingly, the ossification began peripherally, adjacent to the innermost layer of the perichondrium where areas of fibrocartilage had developed. The newly formed bone matrix showed strong immunostaining for type I collagen. Fibrocartilage bordering peripherally on bone matrix revealed only a faint staining for type I collagen, but strong immunoreactivity to type II collagen. The interterritorial matrix of the central chondrocytes failed to react with the type II collagen antibody, in both men and women, from the end of the second decade. These observations indicate that major matrix changes occur at the same time in male and female first rib cartilages. Thus, our findings indicate that ossification in human first rib cartilage does not follow the same pattern as that observed in endochondral ossification of epiphyseal discs or sternal cartilage.