Nonlesions, Unusual Cell Types, and Postmortem Artifacts in the Central Nervous System of Domestic Animals

Abstract

In the central nervous system (CNS) of domestic animals, numerous specialized normal structures, unusual cell types, findings of uncertain or no significance, artifacts, and various postmortem alterations can be observed. They may cause confusion for inexperienced pathologists and those not specialized in neuropathology, leading to misinterpretations and wrong diagnoses. Alternatively, changes may mask underlying neuropathological processes. ''Specialized structures'' comprising the hippocampus and the circumventricular organs, including the vascular organ of the lamina terminalis, subfornical organ, subcommissural organ, pineal gland, median eminence/neurohypophyseal complex, choroid plexus, and area postrema, are displayed. Unusual cell types, including cerebellar external germinal cells, CNS progenitor cells, and Kolmer cells, are presented. In addition, some newly recognized cell types as of yet incompletely understood significance and functionality, such as synantocytes and aldynoglia, are introduced and described. Unusual reactive astrocytes in cats, central chromatolysis, neuronal vacuolation, spheroids, spongiosis, satellitosis, melanosis, neuromelanin, lipofuscin, polyglucosan bodies, and psammoma bodies may represent incidental findings of uncertain or no significance and should not be confused with significant microscopic changes. Auto-and heterolysis as well as handling and histotechnological processing may cause postmortem morphological changes of the CNS, including vacuolization, cerebellar conglutination, dark neurons, Buscaino bodies, freezing, and shrinkage artifacts, all of which have to be differentiated from genuine lesions. Postmortem invasion of microorganisms should not be confused with intravital infections. Awareness of these different changes and their recognition are a prerequisite for identifying genuine lesions and may help to formulate a professional morphological and etiological diagnosis.

Temporal Sequence of Autolysis in the Cerebellar Cortex of the Mouse

“…Post-mortem lysis of the cerebellar granular layer is a well-recognized neuropathological entity in cattle and other Bovidae (Summers et al, 1995;Vandevelde et al, 2012;Wohlsein et al, 2012) and in man (Albrechtsen, 1977a,b;Vinters and Kleinschmidt-DeMasters, 2008;Itabashi et al, 2011), but the temporal sequence of this change, generally attributed to autolysis, has not been investigated previously. Such a study could be useful diagnostically in discriminating post-mortem changes from ante-mortem lesions in this region of the brain and, in veterinary forensic cases, assisting in a determination of the post-mortem interval.…”

Perinatal lamb mortality: an assessment of gross, histological and immunohistochemical changes in the central nervous system

“…That author also stated that in a number of recently published experimental neurotoxicology reports these neurons were misinterpreted as dying or degenerating neurons, and made a plea for increased awareness of this common artefact (Jortner 2006). Autolysis, handling and processing may cause post-mortem morphological changes of the CNS, including vacuolisation and dark neurons and these need to be differentiated from genuine lesions as they may impact aetiological diagnoses (Wohlsein et al 2013). …”

“…Each section was examined for the presence of haemorrhage and neuronal changes using light microscopy and a camera with locked exposure for capturing images. Shrunken, darkly stained neurons, a well-recognised artefact in CNS tissue (Jortner 2006;Wohlsein et al 2013), were present in many sections of brain.…”

Nervous system

“…Just beneath the ependymal layers of the lateral ventricles are progenitor cell rich clusters of the subventricular zone (Figure 8.12) (Hagan et al 2011;Pastrana et al 2011;Fuentealba et al 2012;Walton 2012). In close relation with the ventricular system, they include secretory and sensory organs: the vascular organ of the lamina terminalis, the subfornical organ, the median eminence, the subcommissural organ, the area postrema and the pineal gland (Radovsky and Mahler 1999; Wohlsein et al 2013). The circumventricular organs (Figure 8.12) are another set of structures, which, given their small size, may not be consistently present on H&E sections from all animals examined.…”

“…One is by inadvertently sectioning the brain (generally the cerebral cortex or sometimes the cerebellum) and/or inserting bone fragments into it (Figure 8.15) when opening the skull. Small, dark basophilic neurons with intensely stained shrunken nuclei seen in brain or spinal cord sections are often referred to as dark neurons (Jortner 2006;Garman 2011;Kaufmann et al 2012;Wohlsein et al 2013). At its worst, crushing results in loss of the tissue architecture, but pressure applied on unfixed tissue can also cause microscopic artefacts (dark neurons) (Figure 8.16).…”