Cambios Histológicos del Tejido Muscular Estriado Lingual en Ratas Sprague Dawley (Rattus norvegicus) para Estimar el Intervalo Postmortem

Abstract

The postmortem interval (PMI) equals the time that has elapsed since a human being has died until his postmortem examination. After death, the body experiences modifications in its physical and chemical composition know as postmortem changes expressed by signs that can be analyzed for the calculation of the MPI. The aim of the study was to describe the histological changes present in rat lingual striated musculature in different PMIs. 10 two-month-old male Sprague dawley rats were used. The animals were euthanized and left at room temperature (4-14 °C) to sample the tongue at different PMIs (0, 6, 12, 24, 48, 72, 96 and 120 hours postmortem). The study was carried out considering the recommendations of the Guide for the Care and Use of Laboratory Animals. The samples were fixed in 10% buffered formaldehyde and processed for inclusion in paraplast. 5 µm thick sections were made and stained with HE for analysis with light microscopy. Histological changes in the striated muscle cells of the tongue were associated with the different PMIs. At 6 hours postmortem, there were initial changes in nuclear morphology and its pigmentation. At 12 and 24 hours postmortem, changes in muscle striae and an increase in the number of cases with nuclear alterations were observed. At 48 and 72 hours postmortem, cytoplasmic vacuoles, changes in myofiber coloration, and increased nuclear alterations were evident. At 92 and 120 hours postmortem, a decrease in muscle striae and cell nuclei was observed. The nuclei were pyknotic and pinpoint; there was loss of cell morphology and presence of smooth muscle. In conclusion, changes in the histology of rat lingual skeletal muscle make it possible to estimate MPI. This model could be applicable to forensic medicine.