RESUMEN

The present study reveals developmental changes in the number, the phenotype and the distribution pattern of mast cells (MCs) along the cervical, the thoracic and the lumbar parts of the spinal dura mater. Postnatal infiltration of spinal dura by MCs does not appear to follow a sequential developmental pattern and meningeal MCs are unevenly distributed along the various parts of the examined dura. At each spinal level, areas most densely populated by MCs are the dorsal dura and the dural sleeves of the dorsal (sensory) spinal roots The developmental time course of the total MCs number is characterized by significant fluctuations in all three parts examined, with notable increases at P1, P4, P21 and P60 (peak value) for the cervical part, at P1 (peak value), P7 and P21 for the thoracic part and at P1, P7 (peak value) and P30 for the lumbar part. At P180, MCs number declines to 56%, 33% and 13% of the peak values for the cervical, the thoracic and the lumbar part, respectively. However, a different developmental pattern is followed by each subpopulation of MCs identified on the basis of their staining characteristics, namely connective tissue type mast cells (CTMCs), mucosal type or cells with characteristics of immature mast cells (MTMCs) and mixed type MCs, in each part examined. The findings may be of importance in elucidating physiological and pathological processes in the dura mater and the vertebral column.

Asunto(s)

RESUMEN

The present study examines comparatively the cellular density of disector-counted/Nissl-stained CA1 pyramidal neurons and the morphometric characteristics (dendritic number/length, spine number/density and Sholl-counted dendritic branch points/20 microm) of the basal and apical dendritic systems of Golgi-impregnated CA1 neurons, in the septal and temporal hippocampus of the human and hedgehog tenrec brain. The obtained results indicate that in both hippocampal parts the cellular density of the CA1 pyramidal neurons is lower in human than in tenrec. However, while the human pyramidal cell density is higher in the septal hippocampal part than in the temporal one, in the tenrec the density of these cells is higher in the temporal part. The dendritic tree of the CA1 pyramidal cells, more developed in the septal than in temporal hippocampus in both species studied, is in general more complex in the human hippocampus. The basal and the apical dendritic systems exhibit species related morphometric differences, while dendrites of different orders exhibit differences in their number and length, and in their spine density. Finally, in both species, as well as hippocampal parts and dendritic systems, changes of dendritic morphometric features along ascending dendritic orders fluctuate in a similar way, as do the number of dendritic branch points in relation to the distance from the neuron soma.

Asunto(s)

RESUMEN

It is known that both the dura and the pia mater attract and support the differentiation of mast cells. The present study shows that unevenly distributed mast cells in the cerebral meninges of the rat can be found in perivascular sites and vessel ramification points, but can also be unrelated to the meningeal vasculature. It also documents changes in the number, localization and staining preferences of the mast cells in the two meninges of the developing and mature rat brain. Quantitative examination of all types of histochemically differentiated meningeal mast cells reveals no major (although some exist) differences between right and left side subpopulations, but strongly suggests a different origin and fate of the dural and the pial mast cells. The number of dural mast cells, already high from postnatal day 0, although declining from postnatal day 21 onwards, remains conspicuous up to postnatal day 180. In contrast, pial mast cells are comparatively very few in the first day of the postnatal life, and despite a transient significant increase in the following two weeks, they reach almost zero levels from postnatal day 21.

Asunto(s)

RESUMEN

The present study examines quantitatively the areal and the laminar fluctuations of the vascular network in the visual areas 17, 18 and 18a of the rat cerebral cortex, from postnatal day (P) 1 to P60. For this purpose, the detailed vascular networks of the visual areas, marked after transcardial perfusion of India ink, are analyzed with the use of an image analysis system in order to measure the total vascular density (VD) and the relative density of capillaries (CD), of medium (MD)- and large (LD)-sized vessels in combination with changes in the mean diameter of all three types of vessels. Comparative quantitative microscopy showed that both VD and CD do not exhibit significant interareal differences in the adult rat brain. However, while VD reaches adult values much earlier in area 18a (P21) than in areas 17 and 18 (P60), CD obtains adult values at P31 in areas 17 and 18a, but later (P60) in area 18. Maturation process of laminar VD, CD, MD and LD was not found to follow a simple (i.e. inside-out or mediolateral) sequence, and, in each cortical area, laminar fluctuations of vessels density revealed a complicated developmental pattern, which might be attributed to their changing structural and functional status. Developmental changes in the diameter of capillaries, examined in conjunction with concomitant changes of vascular and capillary density in each area, suggest the existence of angiogenesis in all three visual areas during the third postnatal week of age.

Asunto(s)

RESUMEN

Understanding of place-specific cortical cerebrovascular changes after insult and injury depends on the detailed knowledge of the areal and laminar variations in cortical vascularity. The present study examines comparatively the developmental changes of the total vascular density and the density of capillaries and medium- and large-sized vessels in the primary visual cortex (Oc1), the primary auditory cortex (Te1), and the lateral entorhinal cortex (EntL) of the developing rat brain. Vascular networks in the three cortical areas were marked after transcardial perfusion of India ink and quantified with an image analysis system. Parameters examined exhibited (i) peculiar developmental time course within individual cortical layers and (ii) area- and age-dependent variations. Angioarchitecture in Te1 layers was stabilized earlier than that in Oc1 layers and the period of postnatal development of the vascularity of neocortical sensory areas Oc1 and Te1 appeared to be more protracted compared to that of the phylogenetically older entorhinal cortex. By the end of the first postnatal month, vascular densities in the three cortical areas established a dorsoventral gradient (Oc1 > Te1 > EntL). Finally, in all areas, layer IV was the first layer to obtain adult values of capillary density.

Asunto(s)

RESUMEN

The present study examined quantitatively developmental changes of the vasculature in the dorsal (dLGN) and the ventral (vLGN) lateral geniculate nuclei together with concomitant changes in the number of mast cells (MCs), known for their role in angiogenesis. Vascular network, marked after transcardial perfusion of India ink, and MCs detected with conventional histochemical techniques were examined at postnatal days (P) 1, 8, 14, 21, 31, 90 and 300 of Wistar rats. Quantitative analysis by means of an image analysis system showed age-dependent changes in both vascular parameters [vascular area and relative frequency (%) of capillaries and medium- and large-diameter vessels] and mast cells number in the developing dLGN and vLGN. Despite quantitative differences in the vascularization and MC infiltration between the two nuclei at some age points, MC number, vascular area and the percentage frequency of capillaries exhibited similar developmental time courses, especially up to the end of the first postnatal month. Both MC number and the capillary frequency reached maximal levels at P31 and declined thereafter, following a massive or a partial, respectively, decrease up to P300.

Asunto(s)

RESUMEN

The viability of Campylobacter jejuni strains FRI-CF 401S and FRI-CF 25 inoculated in fresh and frozen beef hamburgers was investigated. Hamburgers were stored in the following conditions: 100% air at 4°C for 15 days, 100% CO2, and 100% N2 atmospheres at 4°C for 60 days and -18°C for 90 days. The data showed that 100% air was the most toxic atmosphere to C. jejuni strains. The C. jejuni populations decreased significantly faster (P ≤ 0.05) in the inoculated hamburgers in modified atmospheres than in those at -18°C. Fresh or frozen beef hamburgers contaminated by C. jejuni could always be a principal source of human campylobacteriosis.