Apoptotic bone cells may be engulfed by osteoclasts during alveolar bone resorption in young rats

Apoptotic bone cells may be engulfed by osteoclasts during alveolar bone resorption in young rats

Author Boabaid, F. Google Scholar
Cerri, P. S. Google Scholar
Katchburian, E. Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
São Paulo State Univ
Abstract The alveolar bone is a suitable in vivo physiological model for the study of apoptosis and interactions of bone cells because it undergoes continuous, rapid and intense resorption/remodelling, during a long period of time, to accommodate the growing tooth germs. the intensity of alveolar bone resorption greatly enhances the chances of observing images of the extremely rapid events of apoptosis of bone cells and also of images of interactions between osteoclasts and osteocytes/osteoblasts/bone lining cells. To find such images, we have therefore examined the alveolar bone of young rats using light microscopy, the TUNEL method for apoptosis, and electron microscopy. Fragments of alveolar bone from young rats were fixed in Bouin and formaldehyde for morphology and for the TUNEL method. Glutaraldehyde-formaldehyde fixed specimens were processed for transmission electron microscopy. Results showed TUNEL positive round/ovoid structures on the bone surface and inside osteocytic lacunae. These structures - also stained by hematoxylin - were therefore interpreted, respectively, as osteoblasts/lining cells and osteocytes undergoing apoptosis. Osteoclasts also exhibited TUNEL positive apoptotic bodies inside large vacuoles; the nuclei of osteoclasts, however, were always TUNEL negative. Ultrathin sections revealed typical apoptotic images - round/ovoid bodies with dense crescent-like chromatin - on the bone surface, corresponding therefore to apoptotic osteoblasts/lining cells. Osteocytes also showed images compatible with apoptosis. Large osteoclast vacuoles often contained fragmented cellular material. Our results provide further support for the idea that osteoclasts internalize dying bone cells; we were however, unable to find images of osteoclasts in apoptosis. (C) 2001 Harcourt Publishers Ltd.
Keywords alveolar bone
bone resorption
bone remodelling
Language English
Date 2001-08-01
Published in Tissue & Cell. Edinburgh: Churchill Livingstone, v. 33, n. 4, p. 318-325, 2001.
ISSN 0040-8166 (Sherpa/Romeo, impact factor)
Publisher Churchill Livingstone
Extent 318-325
Origin http://dx.doi.org/10.1054/tice.2001.0179
Access rights Closed access
Type Article
Web of Science ID WOS:000170532800002
URI http://repositorio.unifesp.br/handle/11600/26606

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