Recent progress of the Golgi technique and electron microscopy to examine dendritic pathology in Alzheimer’s disease

Spinal Alterations of Reil Insula in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that involves numerous cellular and biochemical mechanisms resulting in synaptic alterations and extensive neuronal loss. It is primarily characterized by impairment of memory, associated frequently with mood disorders. Continuous studies have shown that insula may be an important target of AD, but neuropathological alterations have not been described extensively. In the present study, we attempted to describe the morphometric and morphological changes of the spines of Reil insula in AD in comparison with normal aging using a silver impregnation technique. We classified spines into 3 types: (1) long neck, (2) short stubby, and (3) other types; and we measured and correlated the length of them in normal controls and in individuals with AD using ImageJ application. Statistical analysis was based on the Student t test on the basis of 360 cells in SPSS v.17.0, and significance was taken as P < .05.

Mammillary Bodies in Alzheimer's Disease: A Golgi and Electron Microscope Study

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, characterized by irreversible memory decline, concerning no rarely spatial memory and orientation, alterations of the mood and personality, gradual loss of motor skills, and substantial loss of capacities obtained by previous long education. We attempted to describe the morphological findings of the mammillary bodies in early cases of AD. Samples were processed for electron microscopy and silver impregnation techniques. The nuclei of the mammillary bodies demonstrated a substantial decrease in the neuronal population and marked abbreviation of dendritic arbors. Decrease in spine density and morphological abnormalities of dendritic spines was also seen. Synaptic alterations were prominent. Alzheimer's pathology, such as deposits of amyloid-β peptide and neurofibrillary degeneration, was minimal. Electron microscopy revealed mitochondrial alterations and fragmentation of Golgi apparatus, associated frequently with synaptic pathology.

What has electron microscopy contributed to Alzheimer's research?

Electron microscopy has enlarged the visual horizons of the morphological alterations in Alzheimer's disease (AD). Study of the mitochondria and Golgi apparatus in early cases of AD revealed the principal role that these important organelles play in the drama of pathogenic dialog of AD, substantially affecting energy production and supply, and protein trafficking in neurons and glia. In addition, study of the morphological alterations of the dendritic arbor, dendritic spines and neuronal synapses, which are associated with mitochondrial damage, may reasonably interpret the clinical phenomena of the irreversible decline of the mental faculties and an individual's personality changes. Electron microscopy also reveals the involvement of microvascular alterations in the etiopathogenic background of AD.

The hypothalamus in Alzheimer's disease: a Golgi and electron microscope study

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, characterized by irreversible decline of mental faculties, emotional and behavioral changes, loss of motor skills, and dysfunction of autonomic nervous system and disruption of circadian rhythms (CRs). We attempted to describe the morphological findings of the hypothalamus in early cases of AD, focusing our study mostly on the suprachiasmatic nucleus (SCN), the supraoptic nucleus (SON), and the paraventricular nucleus (PVN). Samples were processed for electron microscopy and silver impregnation techniques. The hypothalamic nuclei demonstrated a substantial decrease in the neuronal population, which was particularly prominent in the SCN. Marked abbreviation of dendritic arborization, in association with spinal pathology, was also seen. The SON and PVN demonstrated a substantial number of dystrophic axons and abnormal spines. Alzheimer's pathology, such as deposits of amyloid-β peptide and neurofibrillary degeneration, was minimal. Electron microscopy revealed mitochondrial alterations in the cell body and the dendritic branches. The morphological alterations of the hypothalamic nuclei in early cases of AD may be related to the gradual alteration of CRs and the instability of autonomic regulation.

Staining of dead neurons by the Golgi method in autopsy material

Golgi silver impregnation techniques remain ideal methods for the visualization of the neurons as a whole in formalin fixed brains and paraffin sections, enabling to obtain insight into the morphological and morphometric characters of the dendritic arbor, and the estimation of the morphology of the spines and the spinal density, since they delineate the profile of nerve cells with unique clarity and precision. In addition, the Golgi technique enables the study of the topographic relationships between neurons and neuronal circuits in normal conditions, and the following of the spatiotemporal morphological alterations occurring during degenerative processes. The Golgi technique has undergone many modifications in order to be enhanced and to obtain the optimal and maximal visualization of neurons and neuronal processes, the minimal precipitations, the abbreviation of the time required for the procedure, enabling the accurate study and description of specific structures of the brain. In the visualization of the sequential stages of the neuronal degeneration and death, the Golgi method plays a prominent role in the visualization of degenerating axons and dendrites, synaptic “boutons,” and axonal terminals and organelles of the cell body. In addition, new versions of the techniques increases the capacity of precise observation of the neurofibrillary degeneration, the proliferation of astrocytes, the activation of the microglia, and the morphology of capillaries in autopsy material of debilitating diseases of the central nervous system.