Mechanism of age-dependent involution in embryonic chick notochords |
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Authors: | E Ghanem M Cornelissen H Thierens L De Ridder |
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Institution: | (1) Department of Anatomy, Embryology and Histology, Section Histology, University of Gent, Louis Pasteurlaan 2, B-9000 Gent, (Berlgium);(2) Laboratory for Medical Physics, University of Gent, Gent, (Belgium) |
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Abstract: | To study the possible mechanism of the age-dependent involution of the notochord, isolated mesenchymefree notochords of chick embryos were cultured in vitro and compared with their counterparts in vivo. Two different aspects were evaluated: (1) DNA synthesis measured by 3H]thymidine incorporation and visualized by autoradiography and (2) cell death quantified by counting the number of pyknotic nuclei. The results demonstrate that 3H]thymidine uptake by notochords shows an age-dependent decrease in vitro as well as in vivo. The number of 3H]thymidine-labelled notochord cells, however, is higher in vitro than in vivo. At the same time, there is an age-dependent increase in pyknosis in the notochord in vivo and in vitro. So, during the aging process, the number of both pyknotic nuclei and of 3H]thymidine-labelled nuclei suggest a high turnover of notochord cells in vitro. From these results, we can conclude that the process of involution in aging notochord seems to be controlled by a programmed intrinsic process, which might be influenced partially by the microenvironment in vivo. |
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Keywords: | Notochord [3H]thymidine incorporation pyknosis age-dependent involution |
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