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An estimator of the total number of synapses in neocortex of human autopsy brains based on unbiased stereological principles is described. Each randomly chosen cerebral hemisphere was stratified into the four major neocortical regions. Uniform sampling with a varying sampling fraction in each region of neocortex was performed. The total volume of each neocortical region was estimated using point counting according to Cavalieri's principle. The ethanolic phosphotungstic acid staining technique was modified for synapses in human autopsy brains. The numerical density of synapses in each neocortical region studied was estimated using the disector at the electron microscopical level. The total number of neocortical synapses in each region was estimated as the product of the total volume of neocortex and the numerical density of synapses. The influence of the postmortem fixation delay on the number of synapses was investigated in five large mammals (one dog, one cow, and three pigs), the brains of which were kept under conditions similar to those under which human corpses are normally kept. The apparent decrease of 3.9% in the numerical density of synapses in the large mammals following a 2-day fixation delay was not significant. The average total number of synapses in the neocortex of five young male brains was 164 × 1012 (CV = 0.17). An analysis of the precision of the estimate of the total number of synapses in neocortex indicates that blocks represent both the major source of variation and the largest workload. Using eight blocks per brain the imprecision of the estimate is, however, only 66% of the total variance. © 2001 Wiley-Liss, Inc.

In the Netherlands most murder victims are found 2-24 h after the crime. During this period, body temperature decrease is the most reliable method to estimate the postmortem time (PMT). Recently, two murder cases were analysed in which currently available methods did not provide a su.ciently reliable estimate of the PMT. In both cases a study was performed to verify the statements of suspects. For this purpose a finite-element computer model was developed that simulates a human torso and its clothing. With this model, changes to the body and the environment can also be modelled; this was very relevant in one of the cases, as the body had been in the presence of a small fire. In both cases it was possible to falsify the statements of the suspects by improving the accuracy of the PMT estimate. The estimated PMT in both cases was within the range of Henssge’s model. The standard deviation of the PMT estimate was 35 min in the first case and 45 min in the second case, compared to 168 min (2.8 h) in Henssge’s model. In conclusion, the model as presented here can have additional value for improving the accuracy of the PMT estimate. In contrast to the simple model of Henssge, the current model allows for increased accuracy when more detailed information is available. Moreover, the sensitivity of the predicted PMT for uncertainty in the circumstances can be studied, which is crucial to the confidence of the judge in the results. models only very rough estimates of the e.ect of clothing