Pathogenesis of some neurological immune ultrastructural and morphometrical observations on rat thymus.

Numerous studies on neuro-immuno-modulation indicate that the thymus is involved in many neurological diseases, including experimental allergic encephalomyelitis (EAE). Twenty Lewis rats were induced for EAE. At X, XII, XX and XXX days post-inoculation the animals were killed, and the thymus was recovered and harvested. Specimens of thymus were submitted to morphological light microscopy analysis (1% toluidine blue) and ultra-structural analysis (transmission electron microscopy). Significant morphometric data were collected by examining the images quantitatively and by statistically analysing the values. Our results show that the microenvironment of the thymus is severally involved in acute EAE. Thymocytes and reticular epithelial cells show many changes which are closely related to the pathogenesis of EAE. In particular we observed: (1) inside the cell an increase in intra-cytoplasmic vacuoles, and changes in the thickness of the nuclear membrane, mitochondria, rough endoplasmic reticulum, cellular inter-digitations and cellular electron-density; (2) outside the cell an increase in pericellular translucent halo, intercellular spaces, intercellular contacts and apoptotic and necrotic figures. The evidence of a thymic role in MS may suggest the intriguing therapeutic concept of thymectomy in the management of this neurological disease.

Dopamine receptors in the human dura mater.

Dopamine receptors (Dar) were studied as a component of the nervous dopaminergic system in the human dura mater. Dar were stained in several dural zones (vascular, perivascular, intervascular) in different regions (basal, calvarial, tentorial, occipital, frontal, parietal, temporal) of the cranial meninges. Specimens of human dura mater were harvested from autopsies of 10 elderly male subjects (age range, 60-75 years). Dar were labeled with specific (H3) markers, studied with radiobinding techniques (including liquid scintillation), stained for light microscope autoradiography, and measured by means of quantitative analysis of images. All results were evaluated with statistical analysis to identify significant results. More dural Dar were found in the basal region than in the calvarial one. Moreover, Dar are more abundant in the vascular and perivascular dural zone than in the intervascular one. The vascular distribution of Dar seemed to indicate that Dar play a role in the control of meningeal blood vessels. The location and distribution of D1 and D2 receptors in the human cranial dura mater confirmed the presence of a dopaminergic system, which could play an important role in controlling blood flow and/or other functions of meningeal membranes.

Age-related changes in the human retina.

BACKGROUND: In a previous study, scanning electron microscopy (SEM) showed age-related changes in the rat retina. We carried out a study to evaluate age-related changes in the human retina. METHODS: Samples of fresh retinal tissue obtained from younger (age 22 years or less) and older (age 66 years or more) donors were studied by means of traditional histologic methods and by SEM. Eight retinas were obtained from four donors whose corneas had been used for transplantation, and four retinas were obtained from four subjects whose eyes had been enucleated owing to injury. All morphologic results were subjected to quantitative analysis of images. The concentration of cytoplasmic (free) and structural (tissue-associated) protein in retinal tissue homogenates was determined by means of biochemical methods. RESULTS: There was a decrease in all features studied with the exception of structural protein concentration. The mean retinal thickness (and standard error of the mean) was 426 (34.2) microm in the younger subjects and 261 (18.9) microm in the older subjects. The mean numbers of ganglion cells (and standard error of the mean) were 413.5/mm2 (32.3/mm2) and 256.2/mm2 (26.8/mm2) respectively, of capillaries 3.6/mm2 (1.4/mm2) and 1.8/mm2 (1.2/mm2) respectively, of synaptic bodies 122.4 (4.9) conventional units (CU)/area observed and 38.5 (1.6) CU/area observed respectively, of cellular processes 82.3 (3.1) CU/area observed and 13.1 (1.5) CU/ area observed respectively, and of intercellular connections 36.4 (2.5) CU/area observed and 14.3 (1.4) CU/area observed respectively. The mean concentration of total protein per milligram of fresh tissue (and standard error of the mean) was 92.1 (1.8) microg in the younger subjects and 78.7 (1.3) microg in the older subjects; the corresponding values for cytoplasmic protein were 27.6 (1.3) microg and 11.8 (0.8) microg, and for structural protein, 64.4 (1.6) microg and 86.9 (1.4) microg. All differences between the younger and older subjects were significant (p < 0.001) with the exception of mean concentration of cytoplasmic and of structural protein. INTERPRETATION: The human retina undergoes specific changes with aging. SEM provides new morphometric information regarding age-related changes in photoreceptor cells, bipolar cells and ganglion cells that increases our understanding of this topic. Our results may be adopted as a model or as normal values when studying other changes that may occur in the human retina in pathological conditions.