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Biomedical subjects

H Ditrich

Publications and source records attributed to H Ditrich.

13 recordsLinked to original sources
PubMed1997

Afferent portal venous system in the mesonephros and metanephros of chick embryos: development and degeneration.

BACKGROUND: In the chick embryo, both mesonephros and metanephros have a renal portal system. The classical literature gives uncertain answers about the development and degeneration of the meso- and metanephric portal venous system. Some mesonephric vessels present angiogenic processes to colonize the metanephros, while others show signs of degeneration and disappear together with the mesonephros. The adult avian kidney has a conspicuously placed valve, the renal portal valve. The development of this functionally important renal portal valve has not yet been studied in detail. METHODS: Scanning electron microscopy of vascular corrosion casts has been used in this study. Strong mesonephric degeneration as well as metanephric growth and maturation occur in the developmental stages selected for this investigation (7.5, 9, 11, 14, and 21 days of incubation). RESULTS: The mesonephric afferent venous system in the chick embryo is supplied by two vessels, the posterior and the anterior mesonephric portal veins. The posterior mesonephric portal veins show a similar pattern to the anuran (amphibian) kidney. The anterior mesonephric portal vein has not previously been described. Constrictions were found in this vessel, a probable sign of subsequent degeneration. The metanephric afferent venous system is also supplied by two vessels: the caudal and cranial metanephric portal veins. The caudal metanephric portal vein is derived from the postcardinal vein. The cranial metanephric portal vein grows independently throughout the development of the mesonephric vascular system. It is connected to the vertebral venous sinus already at the beginning of its development. The renal portal valve first appears as a capillary network that communicates with the developing afferent and efferent metanephric venous systems. This capillary network later develops to a venous valve. The metanephric afferent venous system shows typical angiogenic signs in corrosion cast, such as nodular protrusions, holes, and enlarged vessels. CONCLUSIONS: The postcardinal vein first supplies only the mesonephric tissue as a portal vessel. Then it becomes a common source for both kidney generations. Finally it supplies only the metanephric tissue with venous blood. However, two independent vessels were found to supply the cranial renal regions: the anterior mesonephric portal vein and the cranial metanephric portal vein.

Animals↗
PubMed1995

Development and degeneration of the arterial system in the mesonephros and metanephros of chicken embryos.

BACKGROUND: The general morphology of the mesonephric and metanephric arteries in chicken embryos has already been described previously. Moreover, the general basis of glomerulogenesis has also been established. However, the degeneration of the mesonephric vascular system, and especially glomerular degeneration, have not been well established yet. Also the morphology of the metanephric angiogenic buds has not been studied yet. METHODS: Scanning electron microscopy of vascular corrosion casts and critical point dried specimens as well as light microscopy of serially sectioned material has been used in this study. Mesonephric degeneration coincides in time with metanephros growth and maturation in the developmental stages of chicken embryos chosen for this investigation (7.5, 9, 11, and 14 days of incubation). RESULTS: The arterial system of the mesonephros in embryonic chicken is similar to that of the anuran kidney, as described in the literature. The morphology of the degenerating mesonephric glomeruli shows that the glomerular capillaries are more thick, tortuous, and numerous than those in normal glomeruli. The podocytes also show degeneration. The arterial system of the metanephros grows directly from the aorta and from the mesonephric arterial system. During these stages of rapid growth, the metanephros shows angiogenic buds. These angiogenic buds can be either pointed or round blind endings. CONCLUSIONS: The distribution and topography of the mesonephric and metanephric arteries is in general accordance with the literature. The process of glomerular degeneration in the mesonephros seems similar to glomerular senescence in man but is different from that of the aged rat glomeruli. The round angiogenic buds observed in the metanephros resemble tumoral angiogenic buds in some aspects. However, both angiogenesis and the degenerative phenomena are part of the normal developmental process. Consequently, the involved mechanisms are probably under sole genetic control. The system studied here offers therefore the possibility to study vascular growth and degeneration on the same model in physiological conditions without application of vasoactive or pathological agents.

Animals↗
PubMed1993

Technical improvements in corrosion casting of small specimens: a study on mesonephric tubules and vessels of chicken embryos.

The injection technique for corrosion casting of small, embryonic material can be improved by using a "chemical ligature" (cyanoacrylate). With this simple method, leakage of the resin at the injection site is prevented and the mechanical stability of the cannula-vessel coupling is improved. The blood vascular system of chicken embryos as small as Hamburger-Hamilton stage 24 (approximately 4.5 days of incubation) has successfully been injected using this procedure. Corrosion casts of the mesonephric tubular system have been made in a similar manner. Additionally, a simple way for secure transport of the fragile casts by immersion in 10% gelatin is suggested.

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↗
PubMed1990

Kidney structure investigations using scanning electron microscopy of corrosion casts--a state of the art review.

The corrosion casting technique using acrylic resins in the scanning electron microscope (SEM), was originally developed to investigate renal microvascular structure and is now also successfully used in studies on various other organs. However, in the last two decades nearly 100 papers have been published on the renal vascular anatomy of various taxa of vertebrates or on pathomorphological structures of kidneys, using this technique. Analyzing these works, trends and developments in this field can be summed up as follows: The majority of studies are anatomical works on the vascular system of kidneys from all vertebrate classes. In addition, experimental pathological investigations, mostly done using rodents, and documentation of pathologically altered renal structure form another large part of the publications covered in this review. Perspectives for future research on renal systems using this versatile method may be derived from this survey.

Ambystoma↗
PubMed1989

The opisthonephric blood vascular system of the chicken embryo as studied by scanning electron microscopy of microvascular corrosion casts and critical point dried preparations.

Microvascular corrosion casts of chicken embryos between four and 19 days after fertilization have been prepared. The developing kidney was investigated with scanning electron microscopy (SEM). The injection technique and resin composition were modified in order to facilitate the complete replication of native blood vascular systems of specimens as small as 15 mm body length. The development of the opisthonephros was followed from near the beginning of its function until a vascular development comparable to the adult situation was reached. Critical point dried glomeruli show the differentiation of the glomerular visceral epithelium (podocytes) from initially epithelioid to highly branched forms. The embryonic kidney (cranial part of the opisthonephros-mesonephros) shows a construction-principle resembling amphibians that is entirely different from the definitive excretory organ (caudal part of the opisthonephros-metanephros).

Animals↗
PubMed1988

Processing of colloidal gold particles in the glomerular mesangium and macula densa of the duck kidney.

Bovine-serum-albumin coated colloidal gold particles were injected intravenously into healthy, adult domestic ducks. The fate of these tracer particles was followed in a time-sequence up to 4.5 days in the renal glomerular mesangium--distal tubule macula densa junction with transmission electron microscopy. The bulk of particle aggregates is 'trapped' in the mesangial channel system, phagocyted by mesangial cells, exocyted back into the mesangial channels, transported extracellularily towards the vascular hilus, rephagocyted by macula densa cells and expelled into the tubular lumen. This process requires about nineteen hours in the experimental model chosen, although it continues to take place to a much lower extent even 4.5 days after administration of the tracer. This mode of macromolecular excretion may be of interest in connection with the pathogenesis of several forms of glomerulonephritis.

Animals↗
PubMed1987

Scanning electron microscopic investigation of mouse cerebellar macrophages in vitro.

Dispersed monolayer cultures of post-natal mouse cerebella were studied using scanning electron microscopy. Special attention was given to the morphology of the brain macrophages and their interaction with neuronal cells. The brain macrophages resemble other macrophages and mononuclear phagocytes in vitro, reported in the literature. Their ability to induce neuronal growth cones to avoid contact, results in areas devoid of neuronal processes (halos) in this culture system; this seems of considerable interest in connection with their possible developmental role in post-natal reshaping of the brain. Scanning electron microscope observations indicate that these halos are not the result of phagolysis of already established neuronal networks, but can only be induced during neuronal growth and process formation. Established, intact neurons are apparently not altered or harmed by contact with brain macrophages.

Animals↗
PubMed1987

Scanning electron microscopy of vascular corrosion casts in comparative studies on renal vascular structure.

In comparative microcorrosion casting studies on renal vascular systems the following demands should be met: The preparation procedure (anaesthesia, operation, flushing of the blood vascular system, ...) should be in accord with the specific physiological properties of the animal under investigation and the casting procedure (injection, curing, maceration, ...) should be kept constant as far as possible. If these points are considered, comparative data, even of quantitative nature, can be obtained from corrosion casts. Examples of results at the organ, single vessel and intercellular level as well as correlation of the results with physiological data are given.

Animals↗
PubMed1986

Brain macrophages in cerebellar cell cultures.

Brain macrophages were studied in dispersed monolayer cultures of post-natal mouse cerebella. The phagocytotic activity, binding of immunoglobulins, presence and characteristics of nucleoside diphosphatases as well as argentophilia and lipid distribution were tested, with results similar to those for brain macrophages in vivo and for other macrophages in vitro. The macrophages in the cultures showed four different forms with continuous transition from one form to the following and subsequent cell death. No signs of proliferation of this cell type was found. Dynamic investigations showed repelling of neuronal growth cones by certain macrophages, resulting in the formation of areas devoid of neuronal and glial processes around the macrophages. An in vitro model for these cells, described by other authors as being important in post-natal reshaping of the brain, is presented and investigated in this study.

Acid Anhydride Hydrolases↗
PubMed1986

Functional aspects of renal glomeruli based on scanning electron microscopy of corrosion casts, with special emphasis on reptiles and birds.

The glomerular complexity of several species of birds and reptiles is investigated in this study by scanning electron microscopy of vascular corrosion casts. Comparing these results with those of a freshwater teleost and a mammalian species, a trend towards small, simple glomeruli of the avian type, beginning with large, well vascularized glomeruli resembling the type found in fish, can be observed in reptiles. A close correlation between glomerular size and habitat can be established comparing related species having a similar physiological mode of renal function. Entirely different from this sauropsidian evolutionary line of development is the highly complex, large differentiation of the mammalian glomerulus.

Animals↗
PubMedDate not supplied

["Depilation" by micro-algae?].

Itching, reddening and depilation of body hairs was reported by swimmers in the Attersee-lake in Austria. Initially, an environmental crime was suspected. However, further investigations showed that a biological cause was probably responsible for these symptoms. The accrustations found on body hairs turned out in the scanning electron microscope to be dried mucus containing numerous diatoms. The prevailing micro-algae were identified as Cyclotella comensis. Thus, although the phenomenon had a natural, harmless cause, it may happen again given the appropriate environmental conditions.

Austria↗