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Biomedical subjects

L Roncali

Publications and source records attributed to L Roncali.

At least 127 records · Page 7Linked 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)

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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.

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PubMed1985

Vasculogenesis in the chick embryo optic tectum.

The initial formation and further development of the intraneural blood vessel network in the tectum opticum of the chick from the 4th to the 14th incubation day have been analyzed and some quantitative data morphometrically recorded. Vessels have been filled by intracardial injection of India ink in vivo. As inferred from our previous investigations on the vasculogenesis of several districts of the central and peripheral nervous system in the chick embryo, also in the developing optic tectum growth and distribution pattern of the vessels seem to unfold step by step under the local influence of earlier occurring morpho-histogenetic processes of the corresponding neural substratum.

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PubMed1985

Ultrastructural basis of the vessel wall differentiation in the chick embryo optic tectum.

The mode and the temporal sequence of the growth and differentiation processes of the intraneural blood vessels have been ultrastructurally analyzed in optic tecta of 4, 8, 12, 16 and 19 incubation day chick embryos and of chicks 15 days after hatching. The findings suggest that the morphological maturation of the various components of the vascular wall and perivascular spaces, leading to the formation of the blood-brain barrier, unfold according to a spatio-temporal gradient, radially extending from the surface of the tectum rudiment.

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PubMed1984

[Effects of chronic hypoxia on microcirculation of the central nervous system during embryonic development].

In the attempt to know the factors influencing the vasculogenesis and to verify whether the vessel formation and growth are influenced, during different ontogenetic periods, by oxygen deficiency, the intraneural vascular network has been morphometrically analyzed in chicken embryo optic tectum under conditions of aerogenic hypoxia. Chicken eggs, incubated under routine conditions, have been half-painted with melted wax at the 2nd incubation day (i.d.). Fragments of optic tectum, isolated from living embryos at the 8th, 14th and 17th i.d., have been fixed and embedded according to the usual E/M procedures. A parallel series of normally developed embryos of 8, 14 and 17 incubation days has been likewise prepared. On semithin sections from the hypoxic specimens and normal control embryos the area occupied by vessels (Av), the number of vessels (Nv) and the diameter of the radially directed ones (Dv) have been evaluated. The preliminary results indicate that hypoxia evokes, from the 8th to the 17th i.d., an increment of the Av parameter, due first to microvessel neoformation and enlargement from the 8th to the 14th i.d., then from the 14th to the 17th i.d. only to a growth of new capillary branches. The response of the vascular network to the hypoxic condition is more marked from the 8th to the 14th i.d., t.i. when, in relation to the differentiation and the stratification of the neurons, the metabolic requirements of the developing tectum are presumably increased. O2 deficiency causes severe developmental disorders of the cyto- and mieloarchitecture of the tectum: the vascular response can apparently prevent actual damages only when the hypoxic condition lasts for a relatively short time.

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PubMed1984

Development of blood vessels in the sympathetic trunk ganglia of the chick embryo during their histomorphogenesis.

The development of the vascular patterns and the differentiation of the cellular components have been studied in the ganglia of the sympathetic trunk in chicken embryos from the 3rd to the 16th day of incubation. The time and the mode of formation of the extrinsic and intrinsic vascular networks seem to conform to the pattern of growth and differentiation of the nerve cells and to their distribution within the sympathetic ganglia.

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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.

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PubMed1983

[Ultrastructural aspects of vasculogenesis in the optic tectum of the chick embryo].

In chick embryos of 4,8,12 and 19 incubation days the ultrastructure of the intrinsic vessels of the optic lobes has been analyzed. During the early periods of the optic tectum vasculogenesis morphological differences have been observed between the vessels which, arising from the external vascular plexus, radially run through the mantle layer, and the vessels of the deep vascular plexus, which precociously arises by branching and anastomosing of the radial trunks immediately beneath the neuroepithelium. Such differences concerning the endothelium thickness, the characteristics of its luminal and abluminal outline, the time of appearance of the endothelial basement lamina and the glial layer, and the width of the perivascular spaces have been related to the growing patterns of the radial vessels which, at least during the first developmental days, are unbranched trunks and precociously differentiate elongating as the mantle layer become more and more thick, and, respectively, of the vessels of the deep plexus, the morphological maturation of which is belated owing to the continuous sprouting of new vascular sprouts.

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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.

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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↗
PubMed1982

Relationships between nervous component histomorphogenesis of chick embryo spinal ganglia and development of their vascular supply in chorioallantoic grafts.

The blood vessel formation as well as the neuroblast differentiation were studied in chick embryo spinal ganglia grafted onto chorioallantoic membrane, and comparatively in those developing in situ under normal conditions. The preliminary results seem to indicate that also in the grafted spinal ganglia, as already suggested, in previous researches, for the orthotopically developing ganglia, the vascular networks apparently do not exert influences on the nervous substratum morphohistogenesis.

Allantois↗
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.

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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.

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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.

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PubMed1980

[Vessel work development phases in the neural part of the pons in chick embryos].

By means of intravascular India ink injections we have analyzed the early developmental phases of the vessel network in the cranial part of the chick embryo pons. At four and one half days of incubation the first radial endoneural vessels have already entered the ventral portion of the pons and formed with their branches a perigerminative network. Both the external and deep network progressively extend during the subsequent days, and at the 7th day the previously segregated cell groups begin to be encircled by tiny branches from the radial vessels. On the 8th day vessels appear also within the cellular groups and differences in vascular density between the various groups become detectable, apparently depending on their different cell density and differentiation degree. From this stage until the 12th day the vessel denseness undergoes a gradual, general increase, although differences in the vascularization degree between various groups are still appreciable.

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PubMed1980

Relationships between vasculogenesis and morphogenesis in the chick embryo spinal ganglia.

By means of India ink injections in chicken embryos from the 3rd to the 14th incubation day, the development of the vascular pattern in the thoracic and lumbar spinal ganglia has been studied. A rather precise correlation has been observed between the successive steps in the formation of the endoganglionic vessel network and the ordered sequence of the proliferation and differentiation processes of the ganglionic neuroblasts: in fact, the developing vascular pattern seems to conform to the morphogenetic changes gradually undergone by the nervous substratum.

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