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A Lametschwandtner

Publications and source records attributed to A Lametschwandtner.

18 recordsLinked to original sources
PubMed1992

Scanning and transmission electron microscopy of venous sphincters in the rat lung.

The rat pulmonary microvasculature was studied using scanning and transmission electron microscopy of vascular corrosion casts and tissue sections. Special emphasis was placed on small pulmonary venous vessels. The shape of vascular casts was analyzed and interpreted concerning the wall composition of corresponding vessels studied in tissue sections. On the casts of pulmonary venules and small pulmonary veins, narrow or wider annular constrictions were regularly observed. Within these constrictions, marks of circularly running grooves were seen as an additional structural detail, which obviously mimic impressions of single or grouped smooth muscle cells. The depth of the constrictions varies; it may be more or less pronounced, occasionally narrowing down the luminal diameter to approximately 50%. These constrictions are caused by muscular sphincters. In tissue sections of small pulmonary veins, sphincter regions were identified as abruptly appearing single or grouped true smooth muscle cells. Smooth muscle cells may be arranged side by side in a group or bundle or even staked in two or three layers. Between the sphincter regions, the venous wall consists merely of endothelium and an accompanying connective tissue layer. The smooth muscle cells of a sphincter are regularly positioned between endothelial layer and elastic lamina. The smooth muscle cells next to the endothelium form myoendothelial junctions. Autonomic nerves near the sphincters were never seen. The venous sphincters described are suggested to be effective devices involved in blood flow regulation. Blood-borne substances or local tissue hormones might govern sphincter function.

Animals↗
PubMed1992

Glomerular development and growth of the renal blood vascular system in Xenopus laevis (Amphibia: Anura: Pipidae) during metamorphic climax.

Microcorrosion casts of the renal vascular system of tadpoles of the Clawed Frog, Xenopus laevis, were observed by scanning electron microscopy. Glomerular differentiation was studied qualitatively and quantitatively during developmental stages 56-66 (metamorphic climax). The general structure of the renal vascular system corresponds to the pattern commonly found in anurans; however, the arterial supply has conspicuous connecting vessels that supply groups of glomeruli. In the dorsal part of the kidney, qualitative differentiation of glomerular structures precedes quantitative growth. The ventral part of the kidney has larger, well-developed renal corpuscles of nearly adult appearance. Four developmental stages of glomerulogenesis are distinguished morphologically and their glomerular and vascular growth is analyzed.

Animals↗
PubMed1992

Scanning electron microscopy of esophageal microvasculature in human infants and rabbits.

The microvasculature of the esophagus was studied by scanning electron microscopy of vascular corrosion casts in human infants and rabbits. In both species, segmental circumferential arteries arise from main longitudinal arteries, the latter giving off numerous perforating arteries. The tunica muscularis is supplied by branches of circumferential and perforating arteries, the submucosa and its glands by branches of perforatings. Terminal arborizations of perforating arteries feed a subepithelial capillary network. These capillaries are drained by a venous plexus in the lamina propria which is connected to a submucosal venous plexus. Perforating veins, running parallel to the corresponding arteries, connect the submucosal plexus with circumferential veins, and finally empty into main longitudinal veins. Valves were not present in any of the veins. Submucosal veins were less numerous in man than in rabbit. The number and caliber of equivalent vessels in human submucosal plexus decreased from the pharyngoesophageal to the gastroesophageal junction, suggesting the latter to be at particular risk in portal hypertension. The subepithelial capillary network reveals a longitudinal arrangement in rabbits, while the same network shows no preferential organization in human infants. The microvascular architecture of the esophagus in humans and rabbits is comparable, especially in the lay-out of the venous plexuses and the absence of venous valves. Therefore the rabbit could serve as an experimental model for studies on portal hypertension. The present results strongly suggest particular significance of the venous plexus in the lamina propria for the genesis of esophageal varices.

Animals↗
PubMed1992

Microangioarchitecture of the guinea pig gallbladder and bile duct as studied by scanning electron microscopy of vascular corrosion casts.

The microvasculature of the gallbladder, the common bile duct, and the duodenal papilla was investigated in 20 albino guinea pigs (Cavia porcellus) using microvascular corrosion casting and scanning electron microscopy (SEM). Main supplying and draining vessels (first-order vessels) approach the gallbladder along the cystic duct. From the latter, penetrating vessels (second-order vessels) arise which pierce the muscular coat of the gallbladder body to form the plexus of third-order vessels between the muscle coat and the mucosa. Third-order vessels finally branch to supply the subepithelial capillaries, which show a honeycomb arrangement, corresponding to the gallbladder pits. At the areas bordering mucosal pits and beneath the tunicae plicae mucosae, the capillaries form glomera. These structures make the mucosal vasculature suitable for adapting to gallbladder wall distension caused by volume changes. The mucosal capillary glomera may also be involved in absorption of substances from bile, or they could act as buffer zones, counteracting the pressure which develops as the gallbladder volume increases. Venous sphincters occurring at the junction of mucosal vessels with the subjacent third-order veins may regulate blood flow in the mucosal glomera. The neck region as well as bile ducts consist of 2 vascular layers: an inner capillary layer and an outer one containing arterioles and venules. The duodenal papilla has a hemispheric shape and is interposed in the transition zone between the stomach and the duodenum. On the most luminal aspect, the capillaries of the papilla have a ring-shaped arrangement, as do the capillaries of the stomach, surrounding the mucosal glands; the remainder of the papilla is covered by duodenal villi capillaries.

Ampulla of Vater↗
PubMed1990

[Angioarchitecture of keloids. A scanning electron microscopy study of a corrosion specimen].

Three keloids harvested during surgery were prepared for histology and scanning electron microscopy (SEM) of vascular corrosion casts. One well-filled keloid (12 cm x 7 cm) was examined by SEM. This specimen revealed a conspicuous increase in subepidermal venous vessels as well as prominent luminal bulging of the endothelial lining in arterial and venous vessels, shown by prominent surface imprint patterns on cast vessels. There were no tapered or compressed vessels. Blind ending vessels identified by cast morphology as vascular sprouts indicated keloid angiogenesis. The increase in (venous) vessels correlated very closely with the hyperaemic state of the keloid.

Adult↗
PubMed1979

Endothelial lesions after temporary clipping. A comparative study.

The effect of temporary clipping on the arterial endothelium of rats was examined with scanning electron microscopy. The opening pressure of four Heifetz clips was modified by changing the springs. Four different clip forces (20, 35, 45, and 65 gm), four periods of clipping (10, 30, 60, and 180 minutes), and three vessel diameters (smaller than 1 mm, 1.1 to 1.3 mm, and 1.4 to 2 mm) were compared. Different grades of endothelial damage were observed. On gross examination the damage involved a detachment of endothelium and the adherence of platelets to the subendothelial tissue. The duration of clipping seemed to be of more importance than the clip force, whereas the vessel diameter had no recognizable influence.

Animals↗
PubMed1979

[Experimental heterograft tracheal transplants in animals. II (author's transl)].

In sequence with an earlier publication on the results of heterograft tracheal transplants in animals, changes in the Formol-Cialit preserved heterogenous tracheal grafts were studied by light microscopy, and by scanning and transmission electron microscopy. Two main queries arise. Where does the graft respiratory epithelium come from, and what happens to the grafted tracheal cartilage? We found that in the epithelium of graft the number of ciliated cells decreased and that there was ultrastructure evidence of cilial destruction, the goblet cells increased in number, there was a loss of strict polarity of the respiratory epithelium, subepithelial accumulations of cells of probable epithelial origin appeared, and there was a subepithelial accumulation of lymphocytes just beneath the basal lamina. Resorption and transformation of the grafted tracheal cartilage into connective tissue was also observed. Hence, the following conclusions may be made. (1) Small tracheal defects can be corrected by Formol-Cialit preserved heterologous grafts. (2) The mucosa of the host trachea produces a functioning respiratory epithelium in the graft. (3) Tracheal grafts should not exceed 2 x 3 cm in size otherwise a new stenosis from resorption and transformation of grafted cartilage into connective tissue will occur.

Animals↗
PubMed1979

[The pathogenesis of tracheal stenosis following thyroidectomy (author's transl)].

The frequency of trachealmalacia or stenoses following operations for struma or recurrent struma initiated our study of the pathogenesis of such changes. This study revealed that mechanical factors, such as compression of the trachea and the like, had been reported in the literature as the causative factors. The present paper investigates to what extent disturbances in the blood supply of the trachea, particularly after ligature of the inferior thyroid artery during thyroidectomy, influence changes in the tracheal mucosa, the connective tissue, and the adjacent cartilage. In twelve experiments on domestic pigs, the blood supply of the cervical trachea was interrupted. After varying periods of survival time, the animals were sacrificed and the tracheas histologically examined. In all cases, ischemic changes in the tracheal mucosa and cartilage could be found in addition to inflammatory reactions with scar formation. It seems justified to conclude that both mechanical factors and disturbances in local blood supply can cause tracheal tissue changes after thyroidectomy. The inferior thyroid artery and its branches also seem to play a central role in the success or failure of tracheal reconstructions following end-to-end anastomoses after stenosis resections. As a consequence, this paper also deals comprehensively with the detailed anatomy of this vessel.

Adult↗
PubMed1979

[Results of heterologous tracheal transplants in animal experiments (author's transl)].

In the present study, 7 x 15 mm Cialit-preserved human tracheal segments were grafted to the tracheas of five 3-month old piglets. 72-120 days later, the animals were sacrificed and the grafts with proximal and distal control areas were removed. Tissues were then examined macroscopically and by light and scanning electron microscopy. We found that: (1) all grafts had taken well; (2) no animal suffered from clinical signs of respiratory obstruction or inflammation; (3) although luminal diameters of the tracheas increased from 8 mm to 22 mm, the size of the grafts remained unchanged but the resulting tracheal stenosis did not cause respiratory obstruction; (4) the graftet areas showed re-epithelialization. The nature of the re-epithelialization as well as the fate of the submucosa and tracheal cartilage will be reported in a subsequent publication.

Adult↗
PubMed1978

[Light and scanning electron microscopical studies of the soft palate and the tongue in Bombina variegata L (author's transl)].

The soft palate and the tongue of adult Bombina variegata L. were studied by means of light and scanning electron microscopy. In the palate numerous taste-disks were found prominent by their polygonal surface structures. These are caused by longer microvilli at the margins of the different cells of the taste-disk or by deepened margins of the polygonal cells. The surfaces of the cells are slightly convex and are covered by numerous microvilli. In the tongue primarily fungiform papillae were observed (with the exception of the margins were taste-disks similar to those found in the palate were present). Their taste-disks also present polygonal structures, their epithelial cells are characterized by microridges while those of the epithelial folds surrounding the fungiform papillae own microvilli. As special formations within the taste-disks small knob-like protrusions between polygonal cells were found.

Animals↗
PubMed1977

A new cell type in the taste buds of anurans. A scanning and transmission electron microscopic study.

A hitherto undescribed cell type within the fungiform papillae of the tongue of the toad, Bufo bufo (L.) and the taste-disks of the soft palate of Bombina variegata L. was identified by means of scanning and transmission electron microscopy. This cell type is characterized by an apical protrusion carrying numerous microvilli. Bundles of filaments are present in the cytoplasm of the protrusion. Vesicles with electron lucent content and microtubules are present thoughout the cytoplasm of the cell.

Animals↗
PubMed1977

The vascularization of the neural stalk and the pars nervosa of the hypophysis in the toad, Bufo bufo (L.) (amphibia, anura). A comparative light microscopical and scanning electron microscopical study.

The angioarchitecture of the neural stalk and the encephaloposthypophysial portal system of the hypophysis of the toad, Bufo bufo (L.), was studied using three different methods. The neural stalk is mainly supplied by branches of the arteria infundibularis superficialis which form a widemeshed vascular network. Dorsally this network continues into the plexus of the pars nervosa. The vascularization of the pars nervosa is made up of the encephalo-posthypophysial portal system. This portal system consists of a hypothalamic branch (=portion), a mesencephalic and a mesencephalicbulbar branch (=portion). The hypothalamic branch was found to drain the pars ventralis of the tuber cinereum as well as more dorsal regions of the diencephalon. The mesencephalic-bulbar trunk enters the hypothalamic branch. The resulting common stem of the encephalo-posthypophysial portal vein the curves around the retroinfundibular communicating artery, crosses its ventral side and runs caudally. The secondary capillary plexus of the pars nervosa is characterized by well defined capillary plexus of the pars nervosa is characterized by well defined capillary networks which are located at the periphery of the parenchyma of the pars nervosa, thus forming a rostral, dorsal and ventro-caudal net. The central region of the parenchyma of the pars nervosa is supplied only by main branches of the encephalo-postpophysial portal vein. The venous drainage of the pars nervosa is via the vena hypophysea transversa.

Animals↗
PubMed1977

Vascularization of the pars intermedia of the hypophysis in the toad, , Bufo bufo (L.) (Amphibia, Anura). A comparative light microscopical and scanning electron microscopical study. II.

The vascularization of the pars intermedia of the hypophysis of the toad, Bufo bufo (L.) was studied by injection of a mixture of India-ink and gelatine into the circulatory system of the head via the arteria carotis communis. Further methyl-methacrylate corrosion casts of brains were made and the hypophysial region of the corrosion casts was examined with the scanning electron microscope. The results showed that the vascularization of the pars intermedia of the toad hypophysis consists of a single-layered vascular network, which is located on the ventral surface of the pars intermedia. The network is formed by capillaries, which primarily run caudally in a fan-like manner and which show only a few cross-connections. In the rostral region of the pars intermedia this network lies rather superficially, while in the caudal region it slightly penetrates the parenchyma. The vascular network originates from vessels of the neural stalk and from wide capillaries of the rostro-ventral region of the neurointermediate junction. The venous drainage of the pars intermedia is exerted by veins, which leave the caudal region and drain into the veins leaving the venous pole of the pars distalis. The flat, wide meshed vascular net on the ventral side of the pars intermedia, demonstrated in this study, fits into the concept that the pars intermedia of the anuran hypophysis is under the control of nerve fibers coming from the hypothalamus.

Animals↗