EXPRESSION OF P53 AND HSP70 IN RELATION TO APOPTOSIS DURING MECKELS CARTILAGE DEVELOPMENT IN THE MOUSE

The process of Meckel's cartilage development was examined with regard to expression of p53, a tumor suppressor gene product and hsp70, a st ress pro rein (heat-shock protein), in association with the occurrence of programmed cell death (apoptosis). Balb C mice embryos from embryo nic days E13, E14, E15, E16, E17, E18 and 1- and 3-day-old pups were u sed. P53-positive cells were detected first at E15, and were found in the perichondrium of the distal part of Meckel's cartilage. During the degeneration process chondrocytes also became p53-positive. In contra st to p53, the expression of hsp70 was high and widespread in the earl y stages of development (E13-E15); however, it decreased with age, exc ept for Meckel's cartilage, where hsp70 was found in the cytoplasm or nuclei of the hypertrophic cells. Apoptosis was first detected at E14- E15 in the perichondrium of the distal parts of Meckel's cartilage. Th e number of apoptotic bodies increased with age and the ongoing resorp tion of Meckel's cartilage. From the present study it can be concluded that expression of p53 and hsp70 varied during the development of Mec kel's cartilage and that both proteins showed nuclear location in hype rtrophic cells. No direct spatial or temporal correlation was observed between the expression of p53 and hsp70 and the occurrence of apoptot ic bodies.