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T Donáth

Publications and source records attributed to T Donáth.

At least 37 records · Page 2Linked to original sources
PubMed1991

Morphometric and immunohistochemical study on the endocrine cells of pancreatic transplants.

The endocrine cells of embryonic pancreatic tissue fragments transplanted into the anterior eye-chamber of rats for 74 days were investigated immunohistochemically and morphometrically and the results obtained were compared with that of normal tissue. Four types of endocrine cells were identified and their distribution was as follows: insulin: 42-52%, glucagon: 11-28%, somatostatin: 4%, and pancreatic polypeptide-positive cells: 3-6%. Their size in square micrometer were as follows: 153, 110, 38 and 51. The area, number, distribution and topography of these endocrine cells with regard to each other did not differ significantly from that of normal tissue. The area of each islet and their cell population vary considerably both in normal and transplanted pancreas.

Animals↗
PubMed1990

Distribution of acetylcholinesterase--and monoamine oxidase--positive neurons in pancreatic tissue transplant.

Acetylcholinesterase-and monoamine oxidase-positive neuronal elements were investigated in embryonic pancreatic tissue fragments transplanted into the anterior eye-chamber of rats for 28, 77, and 135 d, using enzyme histochemical method. Amongst the components of the parenchymal tissue, only the ductal and islets cells survived. Monoamine oxidase (MAO)- and acetylcholinesterase (AChE)-positive neuronal cell bodies and fibres were found to be considerably many in the surviving and newly formed islets of Langerhans, in the wall and periphery of the tubules. Their topography with regards to these components is similar to that in normal tissue. In normal tissue, MAO-positive fibers abut the basal and lateral parts of acinar cells. AChE-positive neurons are most conspicuous in the islets and in the wall of pancreatic ducts.

Acetylcholinesterase↗
PubMed1990

Morphological findings in long-term pancreatic tissue transplants in the anterior eye chamber of rats.

Morphological changes in 21-day-old embryonic and 2-day-old postnatal rat pancreatic tissue fragments transplanted into the anterior eye chamber of homologous animals for 74, 77, 180, and 534 days were investigated using light and electron microscopic, acetylcholinesterase enzyme, and immunohistochemical methods. The pancreatic acinar cells degenerated and were not observed at this stage of transplantation. The ductal system proliferated and partly differentiated into endocrine cells that subsequently formed many new islets of Langerhans as well. The structures of beta-, alpha-, delta-, and pancreatic polypeptide cells were found to be intact even 1.5 years after transplantation. In addition to this, the organization of these cells inside the islets is similar to that of normal pancreatic tissue. The transplanted tissue fragments were well vascularized with blood vessels and innervated also by serotonergic cells and acetylcholinesterase-positive neurons. It is concluded that pancreatic tissue fragments, with the exception of the acinar component, can grow and survive with intact structure in the anterior eye chamber of homologous rats for up to 1.5 years.

Animals↗
PubMed1990

Ultrastructure of pancreatic light and clear cells in normal and transplanted tissue fragments in the anterior eye-chamber of rats.

The ultrastructure of pancreatic light and clear endocrine cells in normal and transplanted tissue fragments in the anterior eye-chamber of rats was described by electron microscopy. Compared to the dark cells, the light cells contain a conspicuously poorly stained cytoplasmic ground substance with varying number of rough endoplasmic reticulum cisterns and secretory granules. The quantities of these two organelles are inversely proportional to each other. "Light" alpha, beta, delta and pancreatic polypeptide cell-types were identified in normal and transplanted tissue. Out of these, the light alpha cell is the most commonly occurring. The "clear" endocrine cells are much fewer in number than the light cells. They contain well stained cytoplasm with numerous low electron density vesicles and few secretory granules. There is no ultrastructural difference between the light and clear cells in normal and in transplanted tissue for 77 and 534 days. The occurrence of light and clear cells in the transplanted tissue shows that these transplants behave morphologically like normal tissue. These cell types might be related to the different stages of secretory granule synthesis and maturation.

Animals↗
PubMed1989

Formation and exocytosis of secretory granules in the endocrine cells of normal and transplanted pancreas: an electromicroscopic study.

The mechanism of secretory granule formation and exocytosis in the endocrine cells of normal and transplanted rat pancreas was studied using electron microscopy. On the one hand, formation of secretory granules starts with the dilatation of the 2 ends or the vesicularization of the middle parts of rough endoplasmatic reticulum (RER). On the other hand, prohormone ribosomes condense into the vesicles of the GOLGI apparatus. This probably indicates that the GOLGI complex is not the only source of formation of secretory granules. Exocytosis occurs with the formation of an electron dense streak between the perigranular membrane and the apical cell membrane. This is followed by the rupture of the streak at this midpoint allowing the granule to extrude into the space between the cell membrane and the parenchymal basal membrane. This fusion-rupture-extrusion mechanism repeats itself at the parenchymal and capillary basal membranes and also at the endothelium until it gets into the capillary lumen, showing that hormones of pancreatic endocrine cells may be actively transported into circulation as intact secretory granules. There is no significant morphological difference between the mechanism of secretory granule formation in normal and transplanted pancreatic tissue.

Animals↗
PubMed1988

Ultrastructural morphology of light beta cells in pancreatic tissue implanted into the anterior eye-chamber of rats.

The ultrastructure of light beta cells in pancreatic tissue implanted into the anterior eye-chamber of homologous rats was described using electron microscopical method. The light beta cells contain more mitochondria and rough-surfaced endoplasmic reticulum cisternae and dilatated smooth endoplasmic reticuli than the dark beta cells. Their cytoplasm are poorly stained and contain secretory beta granules of similar morphological form to those in the dark cells. The secretory granules are also more heterogenous. The light cells seem to represent the early secretory stages of the beta cells.

Animals↗
PubMed1988

Re-innervation of pancreatic tissue implants in normal and in sympathetically denervated eyes of rats.

Embryonic, newborn and adult pancreatic tissue fragments were implanted into the anterior eye-chamber of rats of the same offspring to determine whether there is any difference in the pattern of their re-innervation. In another experiment the embryonic pancreatic tissue fragments were implanted into sympathetically denervated eyes of homologous rats. Newborn, adult and embryonic pancreatic tissue implants were removed under a stereo-microscope after 17, 45 and 53 days, respectively. The embryonic pancreatic tissue implants in denervated eyes were removed after 46 days. The implants were processed for electron microscopy. The embryonic, newborn and adult pancreatic tissue implants were equally well re-innervated by agranular and granular vesicle-containing nerve terminals and varicosities from the host iris. The embryonic pancreatic tissue implants were also re-innervated in sympathetically denervated eyes, most likely by parasympathetic nerves of the iris. Except for the few intrinsic nerve profiles, the re-innervating nerve fibres seemed to reach the implant stroma through the blood vessels revascularizing the implants. The re-innervation of the endocrine pancreas is more pronounced than that of the whole tissue.

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