Age-related changes in the volume of somata and organelles of cerebellar granule cells.

Because cerebellar granule cells are fixed post-mitotic cells, it is expected that they undergo age-related changes like other neurons. To examine this possibility, a stereological study on granule cells of rat neocerebellar cortex was performed for an age spectrum of 2 to 24 months using eight different age groups. The nucleator method, together with point and intersection counting, was used to obtain primary data; arithmetical calculations determined the secondary data. In the soma, the absolute surface area did not change significantly; the volume did, however, exhibit a significant negative linear trend with age. Excluding dense bodies, the absolute volumes of the cytoplasmic components did not vary significantly. The absolute volume of dense bodies displayed a significant positive linear trend with age. Significant positive correlations were detected between the somatic volume and the absolute volume of either mitochondria or ground substance. It was concluded that granule cells showed a fair degree of morphological stability through 18 months. However, the observed changes warn that accompanying physiological alterations may occur, with putative effects on motor coordination.

A stereological study on the nuclear volume of cerebellar granule cells in aging rats.

A morphometric study on age changes of rat cerebellar cortex (Crus I and Crus II) was carried out. The nuclear volume of the granule cells was estimated by means of two unbiased stereological methods: the nucleator, which enabled the estimation of the number-weighted mean volume (VN), and the point-sampled intercepts method, allowing the determination of the volume-weighted mean volume (VV). These parameters enabled the estimation of the coefficient of variation of nuclear volume in the number-weighted distribution [CV(VN)]. All parameters were determined in eight age groups (2, 6, 9, 12, 15, 18, 21, and 24 months--five animals per age) and the mean values of each age group were compared using one-way ANOVA with post hoc comparisons, and regression analysis. It was demonstrated for the first time, using unbiased techniques, that the nucleus of granule cells of the cerebellar cortex showed a significant decrease in its mean volumes (VV) with age, especially from 21 months onwards. Although CV(VN) was not correlated with age, it was also demonstrated that these cells bear a considerable nuclear size pleomorphy that was maintained throughout the age spectrum.

Do microglia arise from pericytes? An ultrastructural and distribution study in the rat cerebellar cortex.

Both pericytes and microglia are dark cells that may present similar ultrastructure as well as organization of the rough endoplasmic reticulum cisternae; in addition, images that suggest pericytes being released from the basal lamina compartment, some of them looking like forms of perivascular microglia, may be found. Anatomical articulations between pericytes and microglia are observed. A distribution analysis reveals that, in the considered five neocerebellar cortical strata, the percentage of pericytes preponderates over the percentage of microglia; furthermore, there is a highly statistically significant linear trend between the percentages of pericytes and of microglia in connection with their distribution along the cortical strata. This study suggests that, in rat cerebellar cortex, microglia may arise from pericytes. It is also hypothesized that astroglia have an active role in releasing pericytes from the vascular wall.

Age changes in cerebellar oligodendrocytes: the appearance of nuclear filaments and increase in the volume density of the nucleus and in the number of dark cell forms.

A qualitative and quantitative ultrastructural study (volume density of the nucleus and cell countings) on age-related changes occurring in neocerebellar oligodendrocytes of the granular layer was carried out in female albino rats aged 2-24 months. Taking into account the cytological features, two types of oligodendrocytes could be discerned, designated as Type I and Type II. Observations showed that, from 18 months onwards, the appearance of bundles of nuclear filaments running throughout the euchromatin areas are common occurrence in Type II oligodendrocytes. The lowest and highest mean volume density of the nucleus is achieved, respectively, at 2 months (50.67%) and at 21 months (64.93%); the analysis of variance of the parameter with ageing displays a most statistically significant result. There is also a positive and linear correlation between the volume density and age. The percentage of Type I oligodendrocytes (out of the total of counted oligodendrocytes) predominates from 2 to 15 months; after being even at 18 months, the percentage of Type II oligodendrocytes preponderates at 21 and 24 months. Although oligodendrocytes are capable of undergoing mitosis, it is concluded that they are prone to morphological changes with ageing, a warning that the physiology of oligodendrocytes may be eventually affected.

Um novo meio e técnica de diafanizaçäo / Anatomical technique

Os autores propöem uma nova técnica de diafanizaçäo de execuçäo rápida e simples, à custa de uma mistura de hidrato de cloral, álcool polivinílico (Rhodoviol) e ácido láctico. Além da rapidez e simplicidade da técnica, os produtos químicos utilizados säo praticamente atóxicos e desprovidos de cheiro ativo e desagradável

Heterogeneity and death of Purkinje cells of rat neocerebellum (Crus I and Crus II): hypothetic mechanisms based on qualitative and quantitative microscopical data.

The morphological changes that take place with ageing in the soma of what we call clear Purkinje cells (CP cells) are examined by light and electron microscopy. Besides the very obvious lipofuscin accumulation, another kind of space consuming structures become greater in number and complexity, i.e., the occurrence of very pleomorphic degenerating focal zones. Apart from CP cells, dark Purkinje cells (DP cells) indeed appear in increasing numbers with ageing; one subtype (DP-1 cells) has medium dark density revealing dumbbell-shaped mitochondria, ring-shaped Golgi apparatus and lamellated bodies; the other subtype (DP-2 cells) has very dark density presenting pycnotic nuclei with complete nucleolar regression and degenerating mitochondria, but with well developed Nissl bodies and Golgi apparatus. The possibility of DP cells not being technical artifacts is discussed. Quantitative studies are also carried out in Purkinje cell somata: mean volume, surface-to-volume ratio, absolute volume occupied with lipofuscin dense bodies as well as the linear density (number per mm) and percentage of CP and DP cells out of the total population of Purkinje cells. Statistically significant linear trends with age are found for absolute volume of lipofuscin in CP cells and for the linear densities and percentages of either CP or DP cells. The concatenation of qualitative and quantitative data suggests that Purkinje cells of Crus I and Crus II undergo an age-related fall-out. Some clear Purkinje cells may become DP-1 cells and others DP-2 cells. The former reveal signs of slow cellular damage; the latter are suggestively very damaged or even dead cells probably on account of having exceeded the critical threshold of the surface-to-volume ratio leading to asphyxia; indeed, their stout structure does not match slow damage.

Quantitative age-related changes on nuclear invaginations of neocerebellar Purkinje cells.

The aim of this study was to provide stereological data for seeking whether Purkinje neurones increase their nuclear envelope invaginations with age. The nuclear parameters considered were: ratio of absolute surface area to volume, surface density and absolute surface area. The first two parameters did not significantly change, but the absolute surface area exhibited marked variations. Regression studies showed no significant linear correlations between any of the parameters and age; so, the increase in number and/or in depth of the invaginations was not suggested. The association of invaginations with a nuclear cap of Nissl substance is a constant feature, stressing that the physiological importance of the complex is maintained throughout the ageing process.

Age-related quantitative changes in inhibitory axo-somatic synapses on Purkinje cells of rat neocerebellum (Crus I and Crus II).

Morphometric analysis concerning inhibitory axo-somatic synapses on the somata of rat Purkinje cells was carried out. The percentage and the absolute cell surface area occupied with the synaptic junctions as well as their surface-to-somatic volume ratio exhibited significant changes with ageing (from 2 to 24 months). All the parameters revealed the smallest value at 2 months and a peak at 9 months; then, after a decline towards 12 months, they remained fairly constant until 24 months. It is suggested that the observed modifications in the synaptic parameters of the somata would have some connection with compensatory mechanisms for dendritic deafferentation seen with ageing or with the onset and development of the reproductive life of the animals.

Age-related morphometric changes occurring in the somata of astrocytes of the granular layer of rat neocerebellar cortex (Crus I and Crus II).

A quantitative study concerning the age-related changes occurring in the cell body and somatic organelles of neocerebellar astrocytes is carried out, using rats aged 2 to 24 months. Manual stereological techniques are used to determine the following parameters on electron micrographs: the somatic volume, the volume density and the absolute volume of the protoplasmic structures as well as the mean surface of the rough endoplasmic reticulum cisternae per cell. None of the parameters reveals any clear-cut general temporal pattern. The soma and the cell components show statistically significant differences in the parameters with ageing, excepting the dense bodies (relative and absolute volumes) and the Golgi apparatus (relative volume). There are significant positive linear trends between, on the one hand, the somatic volume and, on the other hand, the absolute volume of either of the following structures: nucleus, glial filaments, ground substance and dense bodies. Some linear correlations between the absolute volumes of organelles are also found. Despite the ability for karyokinesis, it is concluded that astrocytes do undergo changes with ageing.

[Right ventricular malformation. Rare malformation of the heart]. / Hypoplasie ventriculaire droite. Malformation rare du coeur.

The AA describe a hypoplastic right ventricular chamber of the heart obtained by autopsy and belonging to a man who died of traumatic lesions and paraplegia. This malformation is very rare and the authors attribute to it the small size of the patient who was below the average Portuguese male height.