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Biomedical subjects

H Aldskogius

Publications and source records attributed to H Aldskogius.

At least 127 records · Page 7Linked to original sources
PubMed1982

The use of anterogradely transported wheat germ agglutinin-horseradish peroxidase conjugate to visualize cutaneous sensory nerve endings.

Small amounts of wheat germ agglutinin-horseradish peroxidase conjugate were injected into the L5 spinal ganglion of adult rats. The conjugate was transported peripherally by the sensory neurons to their cutaneous receptors in the hind paw. Nerve plexa in the skin were heavily labeled, and different types of nerve endings could be clearly distinguished. This method gives new possibilities to study peripheral fibers and nerve endings originating in single sensory ganglia.

Animals↗
PubMed1982

The location of cerebellar-projecting neurons within the lumbosacral spinal cord in the cat. An anatomical study with HRP and retrograde chromatolysis.

The locations of lumbosacral spinocerebellar neurons were examined by two anatomical methods in kittens. In one group of animals chromatolytic changes were provoked by cerebellar lesions. In another group horseradish peroxidase (HRP) was injected into the cerebellum. Projection laterality was investigated by making unilateral spinal lesions prior to the cerebellar HRP injections. Diaminobenzidine (DAB) or tetramethylbenzidine (TMB) was used as substrate fo HRP. The morphological characteristics of HRP-labeled neurons in the TMB-processed material were examined. Neurons marked by the two methods were located within the same regions. A greater number of cells were marked with the HRP method, however, than with the retrograde chromatolysis method. Spinocerebellar neurons were found in laminae IV-IX with large differences with regard to specific locations depending on segmental level. Numerous marked neurons were found in the following areas: laminae IV-Vi in L3-L7, the column of Clarke in L3-L4, the medial part of lamina VII in L6-L7, the lateral part of lamina VII in L3-L4, the dorsolateral nucleus of lamina IX in L3-L6, the ventrolateral nucleus of lamina IX in L4-L5, and the ventromedial nucleus of lamina IX in S3 (and Ca1). Dorsally located neurons were in general more likely to project ipsilaterally than ventrally located neurons. Marked structural differences were frequently observed between spinocerebellar neurons in different locations. These results provide additional information on the anatomical complexity of the spinocerebellar pathways from the lumbosacral region in the cat. Together with results from some other recent anatomical studies on spinocerebellar tracts, they also form a basis for further anatomical and physiological investigations which could contribute to a better understanding of the organization of the spinocerebellar tracts.

Animals↗
PubMed1981

Asymmetries and symmetries in the number of thoracic dorsal root ganglion cells.

The right/left ratio for the number of neurons in individual pairs as well as series of pairs of normal rat and guinea pig thoracic dorsal root ganglia have been investigated. After perfusion of the animals with aldehyde fixatives, the 13 pairs of thoracic ganglia were embedded in resin, serially sectioned, and stained with azure methylene blue. Counts of neuronal nucleoli (with correction for possible split nucleoli) were used as an indicator of the number of neurons in each ganglion. In individual pairs the right/left difference varied between 0 and 47% in the rat and 0 and 26% in the guinea pig. There appeared to be no particular level with a preference for large right/left differences. However, when the total number of neurons from the 13 ganglia on one side were compared with the corresponding figure from the other side, the right/left differences were reduced to less than 3% in the rat and less than 2% in the guinea pig. These results show that the organization of the thoracic spinal nerve unit is markedly asymmetrical at the segmental level, but strictly symmetrical in terms of the total number of dorsal root ganglion cells. The marked asymmetry in individual ganglion pairs necessitates caution when evaluating the effect of unilateral experimental manipulations on the number of neurons in thoracic spinal ganglia.

Animals↗
PubMed1981

Postnatal increase of unmyelinated axon profiles in the feline ventral root L7.

The proportion of unmyelinated axon profiles and possible age-related, degenerative and regenerative alterations were studied ultrastructurally in the L7 ventral root of 25 cats ranging form 3 weeks to 11 years of age. For comparison, the ventral root C6 was examined in 5 of these animals. The sections were taken from a level midway between the proximal and distal ends of the roots. The proportion of unmyelinated axon profiles in the L7 ventral root increased from about 14% to around 31% between 4 and 7 months after birth. Simultaneously, the average number of unmyelinated axon profiles per Schwann cell was doubled from 2-3 to 4-5. Thereafter, these figures remained largely unchanged for at least a decade. The total number of myelinated axons was similar in kittens and in cats. In the C6 root the proportion of unmyelinated axon profiles was about 20%, both in kittens and in young or old adult cats. At both segmental levels in the oldest cats, some unmyelinated axons showed degenerative changes and medium-sized and large axons had features characteristic of demyelination and remyelination.

Aging↗
PubMed1980

Axon reaction in dorsal motor vagal and hypoglossal neurons of the adult rat. Light microscopy and RNA-cytochemistry.

Qualitative light microscopical observations, morphometric measurements, and cytophotometric values for nucleolar and cytoplasmic RNA were compared in axotomized rat dorsal motor vagal and hypoglossal neurons. These data were correlated with consective cell counts and examination of the peripheral nerves. Vagal neurons showed an early prominent chromatolysis, later accompanied by increased cytoplasmic basophilia. Morphometric data showed a transient slight cytoplasmic enlargement but no nucleolar hypertrophy. Nucleolar RNA was unchanged, but cytoplasmic RNA was elevated 7 to 84 days postoperatively. Cell counts demonstrated a final cell loss of about 70%. Hypoglossal neurons showed a moderate chromatolysis. Nucleolar and cytoplasmic areas were enlarged for a short period. Nucleolar and cytoplasmic RNA were elevated about 3 to 14 days and about 3 to 28 days postoperatively, respectively. Cell counts demonstrated a loss of 25% at the longest postoperative survival period. The results indicate that axotomized adult mammalian extrinsic neurons--even those destined to die--accumulate RNA. This response contrasts with axon reaction in many axotomized mammalian intrinsic neurons which appear to undergo depletion of RNA.

Animals↗
PubMed1978

Nerve cell degeneration and death in the trigeminal ganglion of the adult rat following peripheral nerve transection.

Trigeminal ganglia of normal rats and of adult rats subjected to unilateral transection of the infraorbital nerve were studied by light and electron microscopy. Counts of ganglion cells in ganglia on operated and unoperated sides were made following long postoperative survival times. The ultrastructural changes in ganglia of the operated side were studied from 3 to 70 days postoperatively. The quantitative observations show that a considerable loss of ganglion cells takes place on the operated side. The ultrastructural observations demonstrate the occurrence of ganglion cell degeneration, nerve fibre degeneration and phagocytosis by satellite and Schwann cells. The results are compatible with the view that degeneration of trigeminal afferents in the brain stem following lesions of peripheral trigeminal nerve branches is related to retrograde degeneration of trigeminal ganglion cells.

Animals↗
PubMed1976

Electron-microscopic identification of Marchi-positive bodies and argyrophilic granules in the spinal cord white matter of the guinea pig.

Sections from spinal cord white matter of normal and rhizotomized guinea pigs fixed by glutaraldehyde perfusion were stained with Marchi fluid or according to a suppressive silver technique. With the aid of the section-embedding method thin sections, cut from light-microscopically identified areas containing Marchi-positive bodies or argyrophilic granules, were examined in the electron microscope. The results show that the Marchi-positive bodies and argyrophilic granules, which are present in normal white matter, represent different histochemical expressions of the same entity--the myelinoid body. In view of the similarities between myelinoid bodies and myelin fragments formed during Wallerian degeneration it is suggested that this type of so called artifact staining of normal white matter inherent to both methods should instead be considered as an expression of a specificity of the two methods for degenerating nervous elements.

Animals↗
PubMedDate not supplied

Complement and clusterin in the injured nervous system.

Peripheral nerve injury and neuronal degeneration resulting from toxic ricin induce activation of the classical pathway of complement close to the injured motorneuron perikarya or sensory terminals. In contrast, degeneration of central myelinated fibers is not accompanied by complement expression. The main source of complement in peripheral nerve injury and toxic ricin degeneration appears to be microglia. Brain contusion is associated with complement activation. Some of the complement in this situation may derive from plasma, because the blood-brain barrier is disrupted. Clusterin expression is increased in astrocytes along with their activation in the vicinity of lesioned neurons. In addition, axotomized motorneurons show a marked clusterin upregulation. A relationship between clusterin and cell death is suggested by the prominent aggregation of clusterin in neuronal perikarya destroyed by the effects of toxic ricin, as well as by the neosynthesis of clusterin in apparently degenerating nonneuronal cells, presumed to be oligodendrocytes. Our findings indicate that the expression of complement and clusterin are prominent features of neural degeneration and regeneration, as it is in Alzheimer's disease brains as well. The nerve injury conditions described, therefore, offer attractive experimental models to elucidate the roles of these molecular components in neurodegenerative disorders, thereby providing useful insights into potentially new therapeutic approaches in these conditions.

Animals↗
PubMedDate not supplied

Fine structural changes in nerve cell bodies of the adult rabbit dorsal motor vagal nucleus during axon reaction.

Counts of neuronal nucleoli were made in the dorsal motor vagal nucleus (DMV) of the adult rabbit 10, 18, 70 and 90 days following unilateral cervical vagotomy. The structural characteristics of nerve cell bodies in the DMV were studied electron microscopically 2--90 days after cervical vagotomy. The nucleolar counts indicated that 20% of the large DMV neurones had disappeared ipsilateral to the operation 10 days postoperatively (p.o.), 65% 18 days p.o. and 70% 70 and 90 days p.o. No loss of small neurones was found. Large neurones ipsilateral to the operation showed nuclear displacement, infoldings of the nuclear membrane and disappearance of granular endoplasmic reticulum beginning 4 days p.o. and being prominent 6--18 days p.o. At the peak of the response, 10--18 days p.o., reacting neurones showed nucleolar condensation and vacuolation, the appearance of intranuclear electron-dense particles, extensive accumulation of intracytoplasmic lipid droplets, increased numbers of microtubules and neurofilaments, focal mitochondrial aggregates, and widespread mitochondrial degeneration. Ten to 21 days p.o. degenerating neurones were observed. After 30 days p.o. survival a partial recovery of surviving large DMV neurones seemed to have taken place. The findings are interpreted as indications of distubed protein metabolism, oxidative metabolism and intraneuronal transport in the axotomized DMV neurones. The unique response of these neurones compared to previously studied peripherally projecting neurones is emphasized.

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PubMedDate not supplied

Glial cell responses in the adult rabbit dorsal motor vagal nucleus during axon reaction.

Following transection of the vagal nerve on the neck, a dramatic loss of neurons occurs in the dorsal motor vagal nucleus (DMV) of the adult rabbit. The present study describes the light and electron microscopical characteristics of the accompanying glial cell response. The number of microglial cells was considerably increased a few days after nerve injury and remained at a higher than normal level throughout almost the whole period examined. Astrocytes increased to some extent at a later post-operative stage. Ultrastructurally, microglial cells hypertrophied, surrounded degenerating neurons, and contained a variety of inclusion bodies, some of which appeared to be derived from degenerating neuroplasm. Astrocytes also hypertrophied, displayed numerous filaments and glycogen granules in their cytoplasm as well as a substantial number of heterogenous dense bodies. The findings indicate that the principal features of the glial cell response in the rabbit DMV is similar to previously described glial cell changes in other systems. However, the intensity in the response of astroglial cells in the DMV appears to be greater than usually observed, possibly reflecting the degenerative nature of the nerve cell body response.

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