Assessment of histological changes in antemortem gingival tissues fixed at various time intervals: A method of estimation of postmortem interval

Histological changes in lingual striated muscle tissue of human cadavers to estimate the postmortem interval

Although there are physiological methods to determine the postmortem interval (PMI), interval forensic histopathology can be applied to obtain accuracy. The aim was to describe the histological changes in human lingual striated musculature at different PMI. Seven groups were formed according to increasing PMI of 6, 12, 24, 48, 72, 96 and 120 h postmortem (PM). Each group was made up of 16 samples of tongues from each cadaver. The samples were fixed in buffered formaldehyde at 10% and processed for embedding in paraplast. Section 5 μm thick were cut and dyed with H&E for analysis. The study was approved by the Bioethics Committee of the Universidad San Francisco de Quito, Ecuador. The histological changes in the striated muscle cells of the tongue were associated with the different PMI. From 6 to 24 h PM, there were initial changes in the cellular and nuclear morphology. At 48 h PM, at least 50% of the samples presented poorly conserved and reduced muscle striations. At 72 h PM, 100% of the cases presented myofibers with altered morphology, cytoplasmic vacuoles (93.75%), edema (68.55%) and pyknosis (93.75%). At 96 and 120 h PM, the myofibers presented pyknotic nuclei, and they were absent in the rest. The changes in the histology of the human lingual striated muscle make it possible to estimate the PMI, either in the early phase (0-72 h) or the late phase (92-120 h). However, further research is needed to verify, refine and expand on these results.

Evaluation of gingival tissue samples for predicting the time of death using histological and biochemical tests

Thanatochemistry also known as chemistry of death and is used to determine post mortem interval (PMI). It is arguably one of the critical steps in forensic investigation. Recent addition of analyzing biochemical changes along with the traditional methods have gained importance, as they help us to record very early changes in the tissue specimens. In this view, our study aimed to correlate both histological changes and enzymatic changes in gingival tissue samples at intervals of immediate, 1 h, 5 h, 24 h and 48 h after death. Histologic changes noted were loss of epithelial architecture, chromatin clumping, nuclear vacuolation, karryopyknosis, eosinophilia and wide intercellular junctions. Two enzymes which differentiate between the autolytic phase (acid phosphatase) and putrefactive phase (ammonia) of decomposition were evaluated using UV spectrometer. Results in our study demonstrated there were variations as in gradual increase in ammonia levels (1.13±0.24-26.6±2.09) and gradual decrease in acid phosphatase levels (5.61±0.67-1.25±0.53) at different time intervals till 48 h. The cellular changes in gingival tissue could also be related to time. The result of our study helps us to identify potential of enzymatic changes which when correlated with histological reports helps us to predict the time of death accurately. Replicating this experiment in various known taphonomic conditions and other enzymes could highlight the usefulness of gingival tissue samples in determining time of death.

The Potential of Light Microscopic Features of the Oral Mucosa in Predicting Post-mortem Interval

Objectives

The post-mortem interval (PMI) refers to the amount of time elapsed between death and discovery of the body. This study aimed to evaluate light microscopic cellular changes in the oral mucosa and identify the potential of this method for predicting PMI.

Methods

This prospective study was conducted between July 2016 and January 2018 at the Institute of Dental Sciences, Siksha ‘O’ Anusandhan University, Bhubaneswar, India. A total of 150 post-mortem (including 75 gingival and 75 buccal mucosa samples) and 40 ante-mortem (including 20 gingival and 20 buccal mucosa samples) tissue samples were compared using haematoxylin and eosin, periodic acid-Schiff (PAS) and van Gieson stains. Microscopic changes in the epithelium and connective tissue were categorised according to PMI stage as early (<12.5 hours since death), intermediate (12.5–20.5 hours since death) or late (>20.5 hours since death).

Results

Most epithelial cellular changes occurred early, except for arc-shaped nuclei and epithelial shredding which were intermediate and late changes, respectively. However, microscopic changes in the connective tissue were only observable at ≥12.5 hours. There was a progressive decrease in intensity in van Gieson stains and an increase in intensity in PAS stains as PMI increased. Several microscopic features were found to be significant predictors of PMI including epithelial homogenisation, cytoplasmic vacuolation, nuclear degeneration, arc-shaped nuclei, chromatin clumping, red blood cell clumping and lysis, melanin incontinency, myofibril degeneration, salivary gland acini degeneration and epithelial connective tissue separation (P <0.050 each).

Conclusion

These findings indicate that microscopic evaluation of the oral mucosa may be helpful for PMI prediction.

Estimation of postmortem death interval from autopsied tongue tissue: A cross-sectional study

Context:

Estimation of time since death is the preliminary step in any postmortem examination. Although there are various physiological methods to conclude the postmortem, interval histological changes can be applied to obtain precision. However, the utility of oral tissues for such an event is still evolving.

Aims:

The present study was conducted to assess the efficacy of postmortem histological changes that occur in tongue to conclude the postmortem interval (PMI).

Materials and Methods:

After obtaining institutional human ethical committee, tongue tissue was collected for during routine autopsy procedure. The study comprised twelve autopsied tongue tissues. The tissue specimens were subjected to routine laboratory tissue processing procedure and the histological changes were evaluated.

Conclusion:

This is the first study of this kind in the scientific literature to explore the tongue tissue to estimate the PMI. There were definite changes in the epithelium and the connective tissue of the tongue, and these features were highly remarkable at various postmortem time intervals.

Determining the time of death by morphological and immunohistochemical evaluation of collagen fibers in postmortem gingival tissues

The estimation of the post mortem interval (PMI) is still one of the most challenging variables to determine and the different approaches currently used in its estimation generally yield to large post mortem windows. In the present study we combined morphological and immunohistochemical analysis in order to reach a more detailed knowledge on tissue organization and degradation after death. Ultrastructural cellular changes and the extracellular matrix of gingival tissues, collected at different post mortem intervals, were observed by a Transmission Electron Microscopy (TEM), in combination with the immunohistochemical detection of extracellular matrix proteins (i.e. collagen type I and collagen type III) as potential post mortem biochemical markers. The final goal was to find a correlation between morphological modifications, biomarkers expression and the time of death. Samples of gingival tissues obtained from 10 cadavers at different post mortem intervals (short post mortem interval, 1-3 days; mid post mortem interval, 4-6 days; long post mortem interval, 7-9 days) were processed for light microscopy and TEM and they were also immunostained with anti-collagen type I and type III antibodies. Results showed gradual degradation of extracellular matrix in the suboral connective tissue in relation to the different time of death. Moreover PMI was related to an increase of nuclear chromatin condensation and cytoplasmic vacuolization both in epithelial and connective tissues. In conclusion, in addition to traditional forensic approaches to estimate PMI, the combined analyses of cellular morphology, ultrastructure and immunohistochemical expression of collagen proteins allow to better infer the PMI.

HIF1α protein and mRNA expression as a new marker for post mortem interval estimation in human gingival tissue

Estimating the post mortem interval (PMI) is still a crucial step in Forensic Pathology. Although several methods are available for assessing the PMI, a precise estimation is still quite unreliable and can be inaccurate. The present study aimed to investigate the immunohistochemical distribution and mRNA expression of hypoxia inducible factor (HIF-1α) in post mortem gingival tissues to establish a correlation between the presence of HIF-1α and the time since death, with the final goal of achieving a more accurate PMI estimation. Samples of gingival tissues were obtained from 10 cadavers at different PMIs (1-3 days, 4-5 days and 8-9 days), and were processed for immunohistochemistry and quantitative reverse transcription-polymerase chain reaction. The results showed a time-dependent correlation of HIF-1α protein and its mRNA with different times since death, which suggests that HIF-1α is a potential marker for PMI estimation. The results showed a high HIF-1α protein signal that was mainly localized in the stratum basale of the oral mucosa in samples collected at a short PMI (1-3 days). It gradually decreased in samples collected at a medium PMI (4-5 days), but it was not detected in samples collected at a long PMI (8-9 days). These results are in agreement with the mRNA data. These data indicate an interesting potential utility of Forensic Anatomy-based techniques, such as immunohistochemistry, as important complementary tools to be used in forensic investigations.

Oral Pathology in Forensic Investigation

Forensic odontology is the subdiscipline of dentistry which analyses dental evidence in the interest of justice. Oral pathology is the subdiscipline of dentistry that deals with the pathology affecting the oral and maxillofacial regions. This subdiscipline is utilized for identification through oral and maxillofacial pathologies with associated syndromes, enamel rod patterns, sex determination using exfoliative cytology, identification from occlusal morphology of teeth, and deoxyribonucleic acid profiling from teeth. This subdiscipline is also utilized for age estimation studies which include Gustafson's method, incremental lines of Retzius, perikymata, natal line formation in teeth, neonatal line, racemization of collagen in dentin, cemental incremental lines, thickness of the cementum, and translucency of dentin. Even though the expertise of an oral pathologist is not taken in forensic investigations, this paper aims to discuss the role of oral pathology in forensic investigation.