Different eyes, different views. Scanning Electron Microscopy applied to forensic investigations

The Scanning Electron Microscope (SEM) is an extremely versatile instrument, essential in a wide array of applications in forensic analysis: for example, it is used to analyze gunshot residue, bullet fingerprints, bullet wipe or patterns around the bullet hole, to examine traces of foreign material embedded in or adhered to bullets (which can provides critical information in the trajectory reconstruction of spent bullets); to study environmental dusts, fibers (both natural and artificial) and to identify unknown small particles; to detect non visible blood stains; to analyze diatoms in drowning cases; and for ink and paper analysis. One central feature of SEM is its ability of providing both panoramic and highly magnified views of the same sample, giving an almost 3D view of the specimen. It is the ideal trait d’union between macroscopic information collected during autoptic or investigative activity and microscopic information obtained with the light microscope. Above all, SEM allows performing a progressive and targeted microdissection of the sample. In this presentation, a selected number of investigations are shown in order to illustrate through specific cases general purpose applications. An elderly man was killed with several blows of axe at the head. SEM investigation allowed us to reconstruct the sequence of the blows, to recognize the type of weapon, to determine how this latter was used and how sharp it was. These results allowed the police to reject the initial version of the suspected, which was eventually convicted of willful murder. A young man died with multiple traumatic and fulguration lesions. SEM analysis allowed us to perform a detailed study of the burnt tissue and to reconstruct the path of the electric discharge, concluding that the primary causa mortis was an accidental electrocution, which caused the subsequent trauma. A child died of a sudden, dramatic internal bleeding. The autopsy revealed that some time before she had swallowed a coin battery which had become lodged in the oesophagus. Here the decaying products of the battery caused an electro-chemical dissection of the oesophagus and, finally, of the descending aorta. The SEM analysis revealed the details of the progressive degeneration of the surrounding tissues

Ultrastructural findings of congenital dyserythropoietic sickle cell beta thal-associated anemia

The ultrastructural findings of erythroblasts and reticulocytes in one case of congenital dyserythropoiethic anemia (CDA) associated with a haemoglobinopathy, sickle cell beta thalassemia minor (Type V CDA), is described. The observations can be summarized as follows: 1) A lot of large breaks are present in the erythroblast nuclear envelope. 2) Nuclear membrane evaginations are filled with dense loose chromatin. 3) Electron-transparent areas (moth eaten chromatin) are evident in dense chromatin. 4) Electron-dense granular material, related to altered haemoglobin chain storage, is evident in the nucleus and in the cytoplasm. 5) Iron deposits are present in mitochondrial matrix. 6) Myelinic figures are present in reticulocyte cytoplasm. For the first time the ultrastructural findings in this type of associated CDA are described and related to the double origin of clinical symptoms

Morphology of epiphyseal apparatus of a ranid frog (Rana Esculenta)

Morphological, histochemical and ultrastructural investigations on epiphyseal apparatus of Rana Esculenta were made. The most important findings were the following: 1) metaphyseal cartilage is localized inside proximal diaphyseal compact bone as a plug; 2) metaphyseal cartilage do not reduce in thickness during ageing; 3) metaphyseal cartilage do not show vascular invasion and do not mineralize in degenerative zone; 4) trabecular bone was not at al1 evident in this animal; 5) externa1 periosteum is well vascularized and proliferates in correspondence to marginal epiphyseal end of the diaphyseal. From these results the hypothesis that the ranid frog bone growth is not due to metaphyseal metabolism (as in avian and mammals) but to bone periosteal marginal mineralization is reached

Ultrastructural aspects of human nonunion

A histological study on the tissue of nonunion of tibias of two young patients was performed to evaluate the ability of cells to start the mineralization of the matrix. The observations can be summarized as follows: 1) Tissue vessels often appear occluded by thrombotic material; 2) Fibroblasts and chondrocytes found in the nonunion tissue seemed normal, with a good secretion apparatus; 3) The cell membranes were able to produce matrix vesicles; 4) Matrix vesicles and cell membrane looked positive to ALPase reaction, 5) Hydroxyapatite crystals could be observed in the cell matrix or inside matrix vesicles. It may be concluded that cells populating nonunion tissue are well equipped to induct the mineralization of the matrix, but the absence of a blood supply, enough to bring them a normal calcium amount, is the real reason for the nonunion

Infantile cortical hyperostosis (Caffey disease): ultrastructural and immunohistochemical characterization of the peritrabecular cells

The ultrastructure and the immunohistochemical pattern of the cells which are responsible for the bone resorption in the cortical infantile hyperostosis were investigated. The osteoclasts present a great positivity to MB1 antigen and a low positivity to OKM5. Mononuclear cells with primary lysosomes, looking like osteoclast ones are present in high concentration in peritrabecular spaces. These cells show a high positivity to OKM5 antigen and a low positivity to MB1 antigen. The mononuclear granulated cells are positive to tartrate-resistent acid phosphatase. The possible common origin and their co-operation in bone resorption is discussed

The role of proteoglycans in maintaining collagen fibril morphology

The aortic wall contains various heterogeneous proteoglycan populations which interact in different ways with other components of extracellular matrix. Proteoglycans (PGs) are known to provide structural support to the vessel wall as well as to influence specific physiological functions of the tissues. The aim of the present study was to investigate the effects of Chondroitinase AC (Chase), Streptococcal Hyaluronidase (Hyase) and Heparanase on human aortic wall collagen which had been treated previously with 4M GuHCl, in order to verify the effects of selective glycanolytic treatment on type 1 collagen fibril ultrastructure. Following 4M GuHCl treatment, collagen fibrils are seen to have a clearly visible period. Subsequent to GuHCl and Streptococcal Hyase treatment al1 collagen fibrils appear to be completely swollen in thin aperiodic filaments; the typical 64 nm collagen period is completely undetectable. After GuHCl and Chase treatment a small number of collagen fibrils are seen to be swollen in thin fibrils which are mainly localized at some distance from elastic fibres. Following GuHCl and HeparanaseIHeparitinase 111 treatment a considerable number of collagen fibrils appear to be swollen in thin fibrils; the majority of which are situated in the vicinity of elastic fibrils. The swelling of collagen fibrils underlines the fundamental role of proteoglycans in maintaining collagen fibril integrity and periodicity. It is as yet impossible to precisely map interactions between these proteoglycans and collagen fibres. The role of Hyaluronic acid requires further investigation, although the nature of this interaction is undoubtedly a matter of considerable interest