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Biomedical subjects

G Azzali

Publications and source records attributed to G Azzali.

At least 37 records · Page 2Linked to original sources
PubMed1990

Macrophage migration through the endothelium in the absorbing peripheral lymphatic vessel of the small intestine.

TEM and three-dimensional models of the absorbing peripheral lymphatic vessel (ALPA) of the small intestine demonstrate that macrophages migrate from the interstitium into the lumen through the endothelial cell (transcellular pathway). Macrophages cross through a 'migration pore' which arises by an 'erosive process' in the cytoplasmic expansion of the endothelial cell. The pore is completely independent of the intercellular junction which is always sealed by junctional complexes. Furthermore several sites of contact between macrophage and endothelial cell membranes stress a possible functional role played by cellular interactions. Transcellular migration processes under normal conditions are compared with pathological or experimental ones.

Animals↗
PubMed1989

Fine structure of the excretory system of the deep posterior (Ebner's) salivary glands of the human tongue.

Human deep posterior lingual glands (von Ebner's glands) are located beneath the circumvallate papillae. They are formed by tubuloalveolar adenomeres, intercalated ducts and excretory ducts coming together in the main excretory duct. The tubuloalveolar cells, pyramid-shaped, show large and dense secretory granules (clear cored) throughout the cytoplasm, rare basal folds and packed cisternae of rough endoplasmic reticulum (RER) at the basal pole. The columnar cells of the intercalated ducts are arranged in a monolayer. They are characterized by dense, clear-core secretory granules (mostly in the apical cytoplasm), a basal nucleus, well-developed RER and Golgi apparatus, and thin filaments distributed in supra- and perinuclear cytoplasm. Striated ducts are absent. Excretory ducts, coming together in the main duct, are lined by a bistratified epithelium. The inner layer consists of columnar cells showing bundles of tonofilaments with scarce secretory activity. The outer layer is composed of basal cells lying on the basal lamina. The main excretory duct, which opens at the bottom of the vallum, shows a stratified epithelium. The outer side is composed of 2-3 layers of malpighian cells lying on the basal lamina. The inner side consists of a single layer of cuboidal-columnar cells with dense apical granules and well-developed organelles synthesizing and condensing secretions. These cells interpolate with goblet cells, rare mitochondria-rich cells, ciliated cells and numerous small globous cells showing a clear matrix and lacking secretory granules. The cilia show a 9 + 2 microtubular structure with basal bodies provided with striated rootlets. Myoepithelial cells surround with their processes the basal portions of the secretory cells and the intercalated ducts. The conclusions concern some comparative aspects and some hypothesis on the functional role of goblet cells, ciliated cells and epithelial cells lining the different ducts, also in relation to the final secretory product.

Aged↗
PubMed1989

Fine structure of bat deep posterior lingual glands (von Ebner's)

We studied the morphology and ultrastructure of the bat (Pipistrellus k.k. and Rhinolophus f.e.) deep posterior lingual glands (Ebner's glands) during hibernation, summer and after stimulation with pilocarpine. Ebner's glands are formed by serous tubulo-alveolar adenomeres and by an excretory system organized in intercalated ducts, long excretory ducts and a main excretory duct. The latter opens in the vallum which surrounds the circumvallate papillae and in the groove of the foliate papillae. The secretory cells, which lack basal folds, show abundant and dense granules (PAS+, Alcian blue -), microvilli (scarce during hibernation), a Golgi apparatus (well developed during summer and after stimulation with pilocarpine), a large nucleus and RER cisternae stacked at the basal pole. Centrioles, lipid droplets, heterogeneous bodies (in content and density, probably lipofuscin bodies), lysosomal multivesicular bodies and large, dense granules with a microcrystalline structure were also encountered. The lateral membranes of adjacent cells are joined by desmosomes; their interdigitations are neither numerous nor prominent during summer. Microfilaments, often gathered in small bundles, lie in the lateral, peripheral cytoplasm without any relation with desmosomes. In summer and particularly after stimulation with pilocarpine, the apical pole of the secretory cells is characterized by many long microvilli, pedunculated hyaloplasmic protrusions and secretory granules. During hibernation the lumen is filled with secretory material. Myoepithelial cells are arranged among secretory cells or between them and the basal lamina. The short intercalated ducts show similarities with the analogous ducts of the parotid gland. Striated ducts are absent. Excretory ducts are endowed with: a) an inner layer of cuboidal cells characterized by poorly developed cytoplasmic organelles, rare dense granules and a few small microvilli; b) an outer layer of basal cells lying on the basal lamina. Myoepithelial cells are absent. The main excretory duct is lined by a stratified epithelium with an inner layer of conical-pyramidal cells surrounded by two-three rows of basal cells. The conical-pyramidal cells show poorly developed organelles, an apical border with small short microvilli and a prominent terminal web.

Animals↗
PubMed1988

Ultrastructural and seasonal aspects of the kidney lymphatic system of hibernating animals.

The kidney lymphatic system of bat, dormouse and marmot consists of intraparenchymal (interlobar, arcuate, interlobular) and extraparenchymal (capsular) vessels sharing common ultrastructural aspects. We did not observe medullary lymphatics. The qualitative and quantitative seasonal changes in the ultrastructure of the lymphatic endothelium represent not only a species-linked feature but also (and mainly) an evident seasonal fluctuation in lymph formation. Furthermore, these ultrastructural changes emphasize the important role played by the different mechanisms involved in the translymphatic movement of proteins and interstitial fluid with particular regard to the 'vesicular route' and intraendothelial channels.

Animals↗
PubMed1988

Topography and ultrastructure of kidney lymphatics in some hibernating bats.

The kidney lymphatic system of some bats consists of intraparenchymal (interlobar, arcuate, and interlobular) and extraparenchymal vessels (capsular and prehilar connective). These vessels drain lymph via precollecting and prenodal collecting lymphatics into a hilar lymph node. There are no lymphatics in the renal medulla. The lymphatic vasculature (precollecting vessels excluded) is characterized by an endothelial wall lacking basal lamina and fenestrations. The endothelial cells, mostly rectangular in shape, are joined together by overlapping, end-to-end, and complex interdigitating junctions. Cytoplasmic expansions profile and thickness, intercellular junctions and particularly the different categories of uncoated vesicles (free or opened on luminal or abluminal surface) show qualitative and quantitative seasonal variations. Luminal and abluminal cytoplasmic processes appear (when analyzed in tridimensional reconstructions) as "intraendothelial channels." The increased number of these structures during summer characterizes them as dynamic elements and supports the concept of an active role played by them in transendothelial transport. Nevertheless, the main functional role is still ascribed (in addition to membrane transport mechanisms) to the vesicular system, also defined as the "vesicular route." We did not find any open intercellular junctions.

Animals↗
PubMed1983

[Ultrastructure of the lymphatic vessels of the urinary bladder].

The fine structure and morphological aspects of superficial and deep lymphatic vessels of Chiroptera' bladder (Vesperugo savi and Rinolophus f.e.) have been studied, under seasonal, physiological conditions of different lymphatic flux (winter lethargic state and summertime). The endothelial walls of subepithelial, intramuscular and subserosal-peritoneal, lymphatic networks show an uninterrupted course together with both simple and complex intercellular contacts, constantly jointed by specialized junctional complexes, such as zonulae adhaerentes and occludentes. The abluminal surface is often almost entirely encircled by a thick layer of fibrillary connective tissue. Seasonal cytological modifications of possible importance and morphological aspects typical of the each individual network have not been detected in the lymphatic endothelium. On the other hand the abundance distribution of clear intracytoplasmic vesicles and the frequent occurrence of micropinocytotic vesicles in the luminal and abluminal membrane surface have been shown. Canalicular structures have also been demonstrated, even if quantitatively less numerous with respect to those seen in the chiliferous vessels of the same species of Chiroptera. The Authors believe that most of the transendothelial transport in the above mentioned lymphatic vessels occur through the micropinocytotic vesicles and also through the intra-endothelial channels made up by the vessel wall, without any intervention of intercellular contacts or specialized junctions. The possible role of substances within the interstitium in inducing the appearance of canaliculi in the endothelial wall is discussed.

Animals↗
PubMed1983

[The fine structure of the efferent ductules of the duct of the epididymis of some Chiroptera (Vesperugo savi and Vesperugo piccolo)].

The fine structure of the epithelium lining the ductuli efferentes and the ductus epididymis of Chiroptera (Vesperugo savi and Vesperugo piccolo) has been investigated. The epithelium of ductuli efferentes is composed of two cell types: principal and ciliated cells, while the ductus epididymis shows four cell types: principal, clear, basal cells and lymphocytes. Cytological differences in principal and clear cells are described, which allow to subdivide epididymis into three regions: head, body and tail. It has also been possible to recognize in these cells both an absorbing and a synthetic function. Cytological features of principal and clear cells in relation to epididymis' function of spermatidic maturation are discussed.

Animals↗
PubMed1983

[Early ultrastructural findings on lymph node sinuses].

Submandibular and mesenteric lymph nodes of Chiroptera (Rinolophus f.e. and Pipistrellus p.) display a marginal sinus, located between the capsule and the cortical parenchima. There are also trabecular sinuses, which deepen in both the cortical and paracortical zones and medullary sinuses in the zona medullary. All the above mentioned sinuses are made up of a distinct endothelial cell wall lying on a variably thick layer of amorphous substance and collagen fibers. Moreover, the endothelial subcapsular wall of the marginal sinus and the endothelium lying the connective tissue septa form a continuous layer, whereas the endothelium adjacent to the parenchima in the marginal, trabecular and medullary sinuses exhibits and interrupted course, so as to allow a free to and from passage of cells between the parenchimal and sinus compartments. The Authors also compare the ultrastructural features of the lymph node sinuses in Chiroptera with those of other mammals including man.

Animals↗
PubMed1982

Transendothelial transport of lipids in the absorbing lymphatic vessel.

Intraendothelial channels have been shown in the lacteal vessels under normal conditions and during experimentally induced stasis, using ultrastructural and tridimensional reconstruction methods. Through the channels of the lymphatic endothelial wall, free lipid drainage from the interstitium into lymph was detected, although the intercellular junctions did not appear to be modified.

Animals↗
PubMed1982

The ultrastructural basis of lipid transport in the absorbing lymphatic vessel.

Absorbing lymphatic vessels of intestinal villi were studied by electron microscopy tridimensional reconstruction in order to follow the passage of lipid from the interstitium into the capillary lumen. The duodenum and ileum of kittens after milk feeding, fasting and lymphatic stasis were investigated. Lipids reach the lymphatic system by intraendothelial 8-14 micrometers long channels, which are directed from the apical to the basal portion of the lacteals. Endothelial junctions were always intact, indicating that these complexes were not involved in the transport of large size molecules.

Animals↗
PubMed1982

Ultrastructure of small intestine submucosal and serosal-muscular lymphatic vessels.

Lymphatic vessels of small intestine submucosal and serosal-muscular layers in mice and bats have been studied by electron microscopy and tridimensional reconstruction of thin serial sections. Lymphatic endothelium has a continuous appearance, it lacks fenestrations and pores and it is encircled by a thick connective tissue layer. The endothelial wall shows intraendothelial channels, quite similar to those previously described in the lacteal vessels. The author believes that the above mentioned intraendothelial channels, together with pinocytotic vesicles, play a fundamental role in the transendothelial transport of fluids, proteins and macromolecules. Moreover, intercellular specialized junctional complexes do not appear to take any part in this process.

Animals↗