Age and sexually dimorphic changes in costal cartilages. A preliminary microscopic study Olga Rejtarova ´ a,1, *, Petr Hejna b, *, Toma ´s ˇ Soukup c , Michal Kuchar ˇ a a Department of Anatomy, Charles University in Prague, Faculty of Medicine in Hradec Kra ´love ´, S ˇ imkova 870, CZ - 500 38, Czech Republic b Department of Forensic Medicine, Charles University in Prague, Faculty of Medicine in Hradec Kra ´love ´, S ˇ imkova 870, CZ - 500 38, Czech Republic c Department of Histology and Embryology, Charles University in Prague, Faculty of Medicine in Hradec Kra ´love ´, Sokolska ´ 581, CZ - 500 38, Czech Republic 1. Introduction Costal cartilages are hyaline, whitish, and semitransparent cartilages which provide a necessary degree of thorax flexibility. During aging, they become less pliable, yellowish and inhomoge- neous when cut [1,2]. The aforementioned changes in appearance and physical characteristics are due to changes in the micro- structure, particularly dehydration of tissue, yellowish pigment deposits [3], calcification, and ossification [4]. A decrease in the total amount of proteoglycans, changes in the content of chondroitinsulfates and keratansulfate, and production of asbes- toid fibres have been described [5–9]. The changes also relate to the cell component, in particular to the decline in the number of cells, the distribution and the size of chondrons, and other chondrocyte degeneration manifestations [1,10–12]. Cartilages grow with perichondrial apposition, and their transversal diameter enlarges approximately until the third decade. The critical diameter of the cartilage is considered as one of the possible etiological factors concerning costal cartilage changes. When the cartilage attains to this diameter, its middle part is poorly nourished. Degenerative changes first occur in the central part of the cartilage [13,14] while the peripheral zone remains intact for a long time. The first rib cartilage is the exception to this rule due to the fact that its central part ossifies last. X-ray studies found that the ossification of the first rib cartilage proceeds laterally from the upper margin of the manubrial end, and it proceeds medially from the lower margin of the costal end [15]. The process of ossification here is faster and more intensive than the process in the lower ribs. The result is relatively early complete ossification and synostosis of the rib with the sternum [16]. The first rib cartilage ossification is not a degenerative process but an entirely physiological one. Hypertrophic chondrocytes and collagen type X, the typical signs of endochondral ossification, were not found in the first rib cartilage. The mineralization of this cartilage depends only on alkaline phosphatase (ALP) secretion. It has characteristics of both intramembranous and endochondral ossifications. Neither of these Forensic Science International 193 (2009) 72–78 ARTICLE INFO Article history: Received 3 April 2009 Received in revised form 9 September 2009 Accepted 16 September 2009 Available online 12 October 2009 Keywords: Costal cartilage Ossification Sexual dimorphism Age estimation Cartilage canal Forensic science ABSTRACT This study reports changes in costal cartilages that appear at the microscopic level throughout life, especially during the ossification process. The work builds on the results of our previous X-ray study, which confirmed the presence of two sexually dimorphic ossification patterns. This led to questions about the existence of additional sex-specific patterns that relate to the ossification process in costal cartilages. Samples of costal cartilages and adjacent parts of the bones were obtained from the autopsies of 17 corpses. The age range among the cadavers varied greatly, from a newborn baby to 91 years of age. Sections of costal cartilage were routinely processed and stained. Alkaline phosphatase activity was detected using histochemical methods. Collagens type II and X were detected immunohistochemically by monoclonal antibodies. The results of our study show that ossification of costal cartilages can take place in the form of two individual processes, localization and time-separate. Endochondral ossifications in the region of the costochondral zone appear in the first decade, and they correspond to ossifications detected by X-ray in the second decade. The location of sex-specific ossifications is determined by the penetration of cartilage canals into the metaphysial part of the rib. Endochondral intramembranous ossifications in the reserve zone appear after the third decade. These types of ossifications correspond to central globular ossifications detected by X-ray, and they are not sexually dimorphic. They can serve for accurate estimation of age. ß 2009 Elsevier Ireland Ltd. All rights reserved. * Corresponding author. E-mail addresses: rejto@lfhk.cuni.cz (O. Rejtarova ´), hejnap@lfhk.cuni.cz (P. Hejna). 1 Tel.: +420 495816351. Contents lists available at ScienceDirect Forensic Science International journal homepage: www.elsevier.com/locate/forsciint 0379-0738/$ – see front matter ß 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.forsciint.2009.09.009