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Biomedical subjects

M Bertossi

Publications and source records attributed to M Bertossi.

At least 73 records · Page 4Linked to original sources
PubMed1985

[Differentiation of cerebellar Purkinje neurons of the normal and chronically hypoxic chick embryo].

A microscopical and ultrastructural study on the cerebellum development, with peculiar attention to the Purkinje cell differentiation, has been undertaken in chick embryos from the 8th incubation day (i.d.) until hatching, both in normal and hypoxic conditions; the development under hypoxia was obtained by covering, at the 2nd i.d., a half of fertilized egg shells with melted wax (Menkes et al., 1975). The observations, carried out on paraffin, semithin, and ultrathin sections of cerebellum anlagen, indicate that, under normal conditions, the cerebellar "folia" begin to appear on the 9th-10th i.d., and the secondary and tertiary ones are completely formed at the 14th i.d., when also the cortex layers begin to be recognizable owing to the successive migration processes of cells from two germinal layers and the mitotic proliferation of neuroblasts. The Purkinje cells are identifiable only at the 10th i.d. as large neuroblasts, irregularly stratified beneath the external granular layer, and characterized by a scanty amount of basophilic cytoplasm; they progressively acquire features of neurocytes, with abundant basophilic cytoplasm and numerous ramifications of their dendritic tree. The differentiation of Purkinje neurocytes, complete at the 17th i.d., is accompanied by degeneration events affecting some of them, which appear modified in shape, size and both structural and ultrastructural features (e.g. nuclear pycnosis, condensation and/or vacuolization of the cytoplasm). In the hypoxic embryos the main morphogenetic and histogenetic processes normally unfold during the embryonic life and the Purkinje cell differentiation occur like in the normal embryos until the 15th i.d.; afterwards a progressively greater number of them undergoes severe morphological modifications, comparable to those affecting only few neurons in the cerebellum of normally developed embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Blood vessel ultrastructure in the chick optic tectum developing under chronic hypoxia conditions.

The maturation process of blood vessels has been ultrastructurally investigated in the optic tectum of chick embryos kept in a condition of aerogenic hypoxia and of chickens born from fertilized eggs incubated under hypoxia but kept in the open air after hatching. By comparing the fine structure of the intratectal vessels of chick embryos exposed to hypoxia to that of embryos developed under normal conditions, the conclusion has been drawn that O2 deprivation does not prevent the temporal sequence of appearance and/or differentiation of the various vascular wall components (endothelium, endothelial basement lamina, pericytes, perivascular glia), but it produces, at least in a part of the latter, modifications, the type and degree of which apparently depend upon hypoxia duration.

Animals↗
PubMed1983

[Organogenesis of cranial ganglia in the chick embryo: a comparison of the development of blood vessels and neurocytodifferentiation].

Neurohistogenetic and vasculogenetic processes have been analytically compared in several cranial ganglia, ciliary (III nerve), semilunar (V nerve), vestibulocochlear (VIII nerve), petrosal (IX nerve) and nodose (X nerve), of chicken embryos from the 3rd to the 12th incubation day. The results indicate that during the organogenesis of these ganglia the formation of the first intrinsic vessels and the successive development of vascular networks follow the beginning and, respectively, the main steps of the neuroblast morphological maturation. The differences noticed by the Authors as concerns the chronological sequence showed by the vasculogenetic events in the various ganglia have been ascribed to the different proceeding of the neurohistogenesis since blood vessels first appear and build networks where the ganglionic development and differentiation are more precocious.

Animals↗
PubMed1983

[Structural changes of fenestrated capillaries during development of various endocrine glands in the chicken].

The ultrastructure of the blood capillaries has been analyzed in the adenohypophysis, the pineal body, the thyroid and the suprarenal gland of chick embryos of 7, 14 and 19 days of incubation and, respectively, of the adult fowl. During the organogenesis of these endocrine glands the vascular primordia, precociously appearing among the epithelial components, undergo morphological maturative changes leading to the formation of capillaries built of a fenestrated endothelium and an underlying thin layer of pericytes included in a splitting of the endothelial basement lamina. The capillary differentiation processes, almost identical in the mentioned glands, follow a different chronological sequence, occurring precociously in thyroid and suprarenal and later on in adenohypophysis and pineal body. The relationships between the structural modifications of the capillary wall and the morphological and functional differentiation of the endocrine cells during the organogenesis of the glands have been briefly discussed.

Adrenal Glands↗
PubMed1983

Ultrastructural study of the developing blood capillaries in the pineal gland of the domestic fowl.

The ultrastructure of the pineal gland capillaries in chick embryos of 7, 14 and 19 days of incubation and in three month chicks has been analyzed. The results show that vascular primordia are detectable among the pineal developing vesicles on the 7th incubation day. Significant maturative changes in the capillary wall (flattening of the endothelial cells, appearance of pores, narrowing of the perivascular spaces and formation of the endothelial basement lamina) take place during the last days of the embryonic life and are concluded only after the hatching. Relationships between the vasculogenetic and the morpho-histogenetic processes in the pineal body, and some differences in the maturative changes of the vascular wall of the pineal and other chick embryo endocrine glands, have been briefly discussed.

Animals↗
PubMed1982

Preliminary investigation on the submicroscopical structure of blood capillaries of the pineal body in the embryonic and adult domestic fowl.

The morphological changes of the blood network capillaries in the pineal gland of the domestic fowl during embryonic development and in the first post-hatching year have been analyzed. Our preliminary results indicate that the first intrinsic vessels, showing an immature aspect, appear among the epithelial vesicles on 7th-8th incubation day (i.d.), when the pinealoblasts are actively proliferating; then, they drastically increase in number (10th i.d.), but they begin to undergo significant maturative changes only on the 19th i.d., in parallel with the unfolding of the pinealocytes differentiation. Finally they reach the definitive set-up within the first post-hatching year, while the pineal is acquiring its full morphological and functional maturity.

Aging↗
PubMed1981

Ultrastructural changes of the developing blood vessels in the chick embryo adenohypophysis.

A study has been made of the ultrastructural changes undergone by the capillaries of the blood vessel network during development of the pars distalis of the adenohypophysis in the chicken embryo. The adenohypophysial sinusoids attain their full set-up during the last third of embryonic life, and the main features of the differentiation process of the capillary wall concern: (1) a progressive thinning of the endothelium commencing at the 14th i.d., accompanied by a reduction of the cytoplasmic organelles of its cells from the 16th i.d.; (2) a gradual disappearance of the largely overlapping cytoplasmic projections of adjoining endothelial cells, and a progressive increment of the pores, closed by diaphragms, in their thinnest peripheral extensions; (3) a marked narrowing, from the 14th i.d. on, of the perivascular space, which attains its definitive characteristics only at hatching, when the endothelial basement lamina forms. The significance of endothelial porous vacuoles throughout maturation of the vessel wall is discussed, and some remarks on the relationships between histogenesis and vessel development in the chicken pars distalis of the adenohypophysis are advanced.

Animals↗
PubMed1981

An ultrastructural study of the calcification process in tympanosclerotic tissues.

The alterations of the connective tissue components in the middle ear during tympanosclerosis have been analyzed at ultrastructural level. The final steps of this pathological condition are characterized by the disappearance of the blood vessels, cellular degeneration, hyalin degeneration, and calcification. The different features of the inorganic deposits and the cellular origin of the organic structures involved in the calcification process are described.

Basement Membrane↗
PubMed1981

[Perivascular spaces in organogenesis of the cephalic lobe of the hypophyseal pars distalis of the chick].

The modifications of the extent and ultrastructure of the perivascular spaces during the development of blood vessel networks in the pars distalis of the adenohypophysis have been analyzed in normally developing chick embryos, from the 7th incubation day to hatching. The quantitative evaluation of the changes undergone by the perivascular spaces, carried out on semithin sections, showed that their extent gradually decreases and that this reduction is paralleled by an increment of the extent of the capillary bed. The ultrastructural study of the hypophyseal sinusoids allowed a precise determination of the size and the minute morphology of these spaces, which attain their definitive characters only during the late incubation stages, when the endothelial basement lamina forms.

Animals↗
PubMed1980

[The vascular network and the perivascular spaces of the pars distalis of the hypophysis in developing chick embryos].

A quantitative analysis of the modifications undergone by the vascular networks and the perivascular spaces in the rudiment of the adenohypophysis has been carried out in normally developing chick embryos from the 7th incubation day to hatching. The present results point to the existence, during the developmental period mentioned, of a relationship between the extent of the capillary bed and, respectively, of the perivascular spaces, the gradual increment of the former being paralleled by a decrease of the latter. The rate of these events appears to be higher between the 14th and the 16th incubation days, namely when the vessels begin to acquire some of the morphological features typical of sinusoids, their thin walls getting gradually into closer contact with the secretory epithelial cells.

Animals↗
PubMed1979

[Correlations between the processes of cell differentiation and development of blood vessels in the (chick embryo) adenohypohhysis].

Utilizing semi-thin and, respectively, thick sections after indian ink injections, we have analyzed morphohistogenesis and vessel development in the adenohypophysis of chick embryos from the 4th to the 19th incubation day. Our preliminary results indicate that a close correlation exists between cellular differentiation and vasculogenesis. Vessels begin to enter the gland only at the 6th day when the first endocellular granules become detectable, and, from the 10th day, they markedly increase in number and size, gradually acquiring a peculiar sinusoidal arrangement around cellular groups, as cell differentiation further progresses.

Animals↗
PubMedDate not supplied

Ultrastructural and morphometric investigation of human brain capillaries in normal and peritumoral tissues.

Capillaries of peritumoral and normal brain tissues were ultrastructurally and morphometrically investigated to evaluate the changes in peritumoral capillaries connected with the tumor-associated vasogenic edema. The endothelial cells of peritumoral capillaries showed varying thickness, electron-lucent cytoplasm, and structurally normal tight junctions. The basal lamina was thickened, rarefied, and vacuolated. The pericytes were provided with pinocytotic vesicles and phagocytic bodies. The astrocytic glia appeared empty or swollen, with few glycogen granules and a disarranged cytoskeleton; well-preserved glia was occasionally observed. The brain tissue was slightly edematous. No statistically significant differences were observed between normal and peritumoral capillaries as regards diameter, wall thickness, endothelial thickness, and endothelial vesicle density. Instead, the peritumoral capillaries displayed three times as many endothelial surface-connected vesicles, a markedly thicker basal lamina, and significantly reduced extension of pericytic and glial investments. The kind and severity of the vascular modifications, compared with the slight edematous appearance of the nervous tissue, strengthen the hypothesis that peritumoral capillaries could be involved in the edema resolution process.

Astrocytoma↗
PubMedDate not supplied

Angiogenesis induced by B-cell non-Hodgkin's lymphomas. Lack of correlation with tumor malignancy and immunologic phenotype.

Correlations of malignancy grade, immunologic phenotype and angiogenic capacity were studied in B-cell non-Hodgkin's lymphomas grafted onto chorioallantoic membranes of chicken embryos. The angiogenic response elicited by the tumors was significantly greater than the response to normal lymph nodes, but it did not correlate with either the malignancy grade or the immunologic phenotype of the tumors. The elevated angiogenic capacity of neoplastic tissues is confirmed. The results also suggest that the extensive vasoproliferative response required by a rapidly growing tumor is not only controlled by the neoplastic cell population but, probably, by the host-response as well.

Adult↗