Intra-axonal corpora amylacea in the peripheral nerve seen in a healthy woman

Cerebral Corpora amylacea are dense membranous labyrinths containing structurally preserved cell organelles

Corpora amylacea are cell-derived structures that appear physiologically in the aged human brain. While their histological identification is straightforward, their ultrastructural composition and microenvironment at the nanoscale have remained unclear so far, as has their relevance to aging and certain disease states that involve the sequestration of toxic cellular metabolites. Here, we apply correlative serial block-face scanning electron microscopy and transmission electron tomography to gain three-dimensional insight into the ultrastructure and surrounding microenvironment of cerebral Corpora amylacea in the human brainstem and hippocampal region. We find that cerebral Corpora amylacea are composed of dense labyrinth-like sheets of lipid membranes, contain vesicles as well as morphologically preserved mitochondria, and are in close proximity to blood vessels and the glymphatic system, primarily within the cytoplasm of perivascular glial cells. Our results clarify the nature of cerebral Corpora amylacea and provide first hints on how they may arise and develop in the aging brain.

Intramuscular corpora amylacea adjacent to ileal low-grade neuroendocrine tumours (typical carcinoids): a light microscopic, immunohistochemical and ultrastructural study

AIMS

The purposes of this study are to (1) document the prevalence of intracytoplasmic inclusions adjacent to ileal well-differentiated neuroendocrine tumours (WNETs), (2) examine whether and how tumour and patient characteristics are associated with inclusions and (3) investigate their properties on special stains and electron microscopy in comparison with corpora amylacea (CA).

METHODS

We examined the resection slides from 26 ileal, 5 gastric and 5 rectal cases of WNET. Inclusions were readily identified with H&E staining. Histochemical, immunohistochemical and ultrastructural evaluations were performed on the block with the highest number of inclusions.

RESULTS

Intracytoplasmic inclusions occurred adjacent (<1 mm) to 15 of 26 (57.7%) ileal WNETs. Patients with and without inclusions were of similar mean ages (59.5 vs 57.4 years; p=0.88), but NETs with inclusions were larger than those without inclusions (3.3 vs 1.7 cm, p=0.03). Inclusions were neither associated with gastric (mean age=65 years, mean diameter=1.5 cm) or rectal WNETs (mean age=47.8 years, mean diameter=0.5 cm) (p=0.01), nor were they present >1 mm from ileal NETs. CA stained strongly for ubiquitin, DPAS and Alcian blue; faintly and peripherally for desmin and smooth muscle actin and negatively for calcium. Ultrastructurally, their appearance was consistent with filaments, some with cores of particle matter.

CONCLUSIONS

Our results suggest that these inclusions are virtually identical to CA and present adjacent to the majority of ileal WNET. They may be the result of a degenerative process, possibly due to chronic myocyte stress from an infiltrating slow growing tumour mass or local hormonal effects.

Reduction in number of corpora amylacea with advancing histological changes of glaucoma

Retina and optic nerve of eyes enucleated due to an iris ring melanoma or a malignant melanoma of the ciliary body were studied to investigate the correlation between corpora amylacea count and glaucoma stages. Ten eyes from ten patients [age: 62.3 +/- 13.0 (mean +/- SD); range 43-84 years] were used for the present study. Eight eyes had shown elevated intraocular pressure readings preoperatively. The corpora amylacea count was correlated with histomorphometric changes of the intra- and parapapillary region. The corpora amylacea count of the retinal ganglion cells decreased significantly with increased histological ratio of cup to disc, decreased retinal nerve fiber layer thickness, and increased optic cup depth. There was no significant correlation between the corpora amylacea count of the bipolar cells and each histomorphometric datum. These results suggest that the corpora amylacea of the retinal ganglion cells decrease in number with advancing histological changes of secondary glaucoma.

Corpora amylacea in glaucomatous and non-glaucomatous optic nerve and retina

We studied the occurrence, location, and size of corpora amylacea (CA) in periodic acid-Schiff (PAS)-stained histological sections of the retina and optic nerve. The glaucoma group included 48 blind eyes obtained from 48 patients (mean age: 64 +/- 13.9 years; range 26-83 years) with advanced secondary angle-closure glaucoma. The non-glaucomatous group consisted of 45 non-glaucomatous eyes from 45 patients (mean age: 62.1 +/- 12.2 years, range 34-78 years) suffering from malignant melanoma of the choroid, and six autopsy eyes obtained from young individuals (age range 2.5-29 years). The mean diameter of CA at the level of the retinal ganglion cells (retrolaminar: 10.92 +/- 5.15 microns, intralaminar: 10.97 +/- 5.04 microns, prelaminar: 9.17 +/- 4.53 microns, nerve fiber layer: 8.56 +/- 4.27 microns) was significantly larger (P < 0.0001; Wilcoxon-Mann-Whitney test) than their size at the level of the bipolar cells (inner plexiform layer: 3.79 +/- 1.30 microns). The count of CA in sections from non-glaucomatous subjects aged 2.5 to 78 years (45 eyes with malignant melanoma and 6 autopsy eyes) increased significantly (P < 0.01) with advancing age. CA occurred significantly more often (P < 0.0001) in eyes with melanoma (45.7 +/- 29.4 per section) than in eyes with glaucoma (4.7 +/- 6.9 per section). These results suggest that CA represent intraneuronal aging products that are diminished in eyes with end-stage glaucoma due to neuronal loss.

Polyglucosan body disease

Adult polyglucosan disease has been described in 15 cases. All had signs of peripheral neuropathy, upper motor neuron signs, and 12 of the 15 had sphincter problems. Dementia was prominent in 8 of 15 cases. We reported 2 cases that contained these clinical features. Electrophysiological studies showed axonal neuropathy. Somatosensory evoked potentials on the second patient were abnormal. Sural nerve biopsy showed clusters of polyglucosan bodies. Although the presence of polyglucosan bodies in biopsy is nonspecific, the number as well as the clinical features are necessary to make the diagnosis. Branching enzyme activity in muscle extracts of the muscles were normal. Hence, a specific enzyme abnormality is not yet known.

Polyglucosan bodies in sural nerve biopsies

The presence of polyglucosan bodies in sural nerves collected over a 16-year period was studied in relation to age, sex, presence of polyneuropathy, and concomitant presence of central nervous system disorder. Polyglucosan bodies have been seen in only one patient without a polyneuropathy. This patient was suffering from Lafora's disease. In all other sural nerves positive for polyglucosan bodies a polyneuropathy was present. Within this group the prevalence of polyglucosan bodies was positively correlated with age, and if a central nervous system disorder was associated, this prevalence was more distinct. With semiquantitative measurements of the surface of polyglucosan bodies a significant correlation was found between age and percentage of large bodies.

Polyglucosan bodies in intramuscular motor nerves

The presence of polyglucosan bodies was studied in intramuscular motor nerves of 292 muscle biopsies. These biopsies were classified into five diagnostic categories and investigated for the presence of polyglucosan bodies in relation to age and sex. Their presence was nonspecific in patients over 20 years, the only correlation being with ageing. Under 20 years, their presence pointed to the diagnosis of Lafora's disease. In cases in which both a muscle biopsy and a sural nerve biopsy were performed, the former appeared to contain these polyglucosans more frequently.

Polyglucosan bodies in the sural nerve of a diabetic patient with polyneuropathy

In the sural nerve of a 62-year-old woman with impaired glucose tolerance test and polyneuropathy, many intra-axonal polyglucosan bodies were observed. Polyglucosan bodies have been described in spontaneously or alloxan-diabetic rats, but are not usually observed in human diabetic neuropathy. Since intra-axonal polyglucosan bodies can occur in the sural nerve in various diseases and in aging, they are considered as non-specific changes. Their presence is probably related to a primary axonal neuropathy.

Intra-axonal polysaccharide deposits in the peripheral nerve seen in adult polysaccharide storage myopathy

This is the first report of an adult polysaccharide storage myopathy demonstrating polysaccharide deposits within the axons of the peripheral nerve. Histochemical and electron-microscopic studies revealed that the intra-axonal deposits were basophilic, PAS-positive, diastase-resistant, and composed of filamentous and granular material. The structural similarity among the polysaccharide deposits in our case, amylopectin-like materials in type IV glycogenosis, Lafora bodies, corpora amylacea, and polyglucosan bodies is discussed.

The ultrastructure of intramuscular nerves in amyotrophic lateral sclerosis

Muscle biopsies of 11 patients suffering from amyotrophic lateral sclerosis (ALS) were examined and the i.m. nerves found in seven of them were examined by electron microscopy. In atrophied muscles there was a marked decrease of myelinated fibers. The ultrastructure of the remaining myelinated axons showed changes in the neurofilaments, mitochondria, and vesicles. There was a decrease in the number of unmyelinated fibers as well as the myelinated fibers. Occasionally, there was an increase of unmyelinated fibers containing small fine axons. There were corpora amylacea in unmyelinated axons and banded structures in the extracellular area of the Schwann cells of the unmyelinated fibers. Some of these findings were considered as the ultrastructural features of degeneration and regeneration in i.m. nerves of motoneurons in ALS.

Ultrastructural observations on axonal swelling in the human gracile nucleus

The morphology of the spheroids in human gracile nuclei was studied by light and electron microscopy. Various spheroids encountered in the present study could be classified into three types based on the internal structure: The first one was chiefly composed of many irregular homogeneous dense bodies, multivesicular bodies seemed to deposit multicentrically in an axon in the early stage of "ballon" formation and coalesce to form larger ones. The second was characterized by a marked accumulated of closely approximated mitochondria and dense concentric bodies. In the third the most characteristic findings were neurofibrillary accumulation and aggregations of dense bodies. These findings showed some divergence from those of dystrophic axons and the last two mimic those of degenerative or regenerative axons, which suggested that axonal swelling (including dystrophic axon) is not characteristic reaction of specific disease but rather nonspecific one to a variety of noxious stimuli. With light microscope, it was difficult to distinguish balloons with different structures since they were quite diverse and manifold in their shape, size, appearance and stainability. Intra-axonal corpora amylacea were seen in most cases and their incidence appeared to be nonspecific for any diseases.

Nemaline myopathy: histological, histochemical and ultrastructural studies

Histological, histochemical and ultrastructural studies were performed on muscle biopsies from three siblings with congenital nemaline myopathy. Histological studies revealed type I fibre atrophy and type II fibre paucity. Ultrastructural studies of intramuscular nerves showed that the axonal diameters were very narrow compared with the width of myelin lamellae. Granular or membranous osmiophilic material occurred in the adaxonal Schwann cell cytoplasm and had a periodicity of 33--38 A. The neuromuscular junctions showed degenerative features such as glycogen granules or myelin figures in 27.1% of total terminal axons. The secondary synaptic clefts were markedly decreased in number and short in length. Myotendinous junction-like structures were found in 5.5% of the muscle fibres near the neuromuscular junctions, and often near sites of fibre-splitting. Rods in nemaline myopathy might be caused as a result of longitudinal splitting and disruption of fibres due to deficient regeneration of the muscle fibres associated with neurotrophic abnormalities.