Special pattern of endochondral ossification in human laryngeal cartilages: X‐ray and light‐microscopic studies on thyroid cartilage

Abstract

Endochondral ossification is a process that also occurs in the skeleton of the larynx. Differences in the ossification mechanism in comparison to growth plates are not understood until now. To get deeper insights into this process, human thyroid cartilage was investigated by the use of X-rays and a series of light-microscopic stainings. A statistical analysis of mineralization was done by scanning areas of mineralized cartilage and of ossification. We detected a special mode of endochondral ossification which differs from the processes in growth plates. Thyroid cartilage ossifies very slowly and in a gender-specific manner. Compared with age-matched women, bone formation in thyroid cartilage of men is significantly higher in the age group 41-60 years. Endochondral ossification is prepared by internal changes of extracellular matrix leading to areas of asbestoid fibers with ingrowing cartilage canals. In contrast to growth plates, bone is deposited on large areas of mineralized cartilage, which appear at the rims of cartilage canals. Furthermore, primary parallel fibered bone was observed which was deposited on woven bone. The predominant bone type is cancellous bone with trabeculae, whereas compact bone with Haversian systems was seldom found. Trabeculae contain a great number of reversal and arresting lines meaning that the former were often reconstructed and that bone formation was arrested and resumed again with advancing age. It is hypothesized that throughout life trabeculae of ossified thyroid cartilage undergo adaptation to different loads due to the use of voice.

The Speaking Voice in the General Population: Normative Data and Associations to Sociodemographic and Lifestyle Factors

“…As testosterone substitution leads to vocal changes, 35 testosterone depletion may as well alter the voice. Furthermore, endochondral ossification takes place in the laryngeal cartilage, a process that occurs more distinctively in men between 41 and 60 years compared with age-matched women, as was shown by Claassen et al 39 This increases the tension on the vocal folds, which causes an increase in frequency. The same mechanism reduces the elasticity of the vocal folds.…”

Sonographic evaluation of the endochondral ossification process of the thyroid cartilage in children

“…Thyroid cartilage consists of hyaline cartilage, which undergoes calcification and ossification as part of the aging process. Histochemical and light microscopic studies by Claassen et al have shown special mode of endochondral ossification in the thyroid cartilage . The ossification process takes place in the central cartilage layer that contains hypertrophic chondrocytes.…”

“…Vascularization of the cartilage canals brings the osteoblasts and chondroclasts to lay down osteoid matrix on the rims of mineralized cartilage. After mineralization of the osteoid matrix, the ossification process results in bone formation . Based on these histochemical and light microscopic studies, we know that the mineralization and ossification process begins earlier than puberty with the chondroid matrix changes.…”

“…Studies investigating the ossification process of laryngeal structures, especially of the thyroid cartilage, were generally performed with radiograph examinations and showed that thyroid cartilage ossification process starts when most of the growth plates have closed, which corresponds to the end of the second decade and continues until advanced ages. They also showed that cartilage mineralization and ossification start at the posterior and inferior border of the thyroid cartilage and spread out to rest of the laminae . Information from histopathological and light microscopy studies of the endochondral ossification process of thyroid cartilage has demonstrated that complex chondroid matrix changes occur in the first decade of life and establish a ground for mineralization and ossification …”

“…They also showed that cartilage mineralization and ossification start at the posterior and inferior border of the thyroid cartilage and spread out to rest of the laminae . Information from histopathological and light microscopy studies of the endochondral ossification process of thyroid cartilage has demonstrated that complex chondroid matrix changes occur in the first decade of life and establish a ground for mineralization and ossification …”