Akademik Anton Švajger : (1935. – 2002.) Bradamante, Želimir
Radovi Zavoda za znanstvenoistraživački i umjetnički rad u Bjelovaru,
12/2017, Volume:
10, Issue:
10
Journal Article, Conference Proceeding
Peer reviewed
Open access
Akademik Anton Švajger, liječnik, od dolaska u Zavod za histologiju i embriologiju Medicinskog fakulteta Sveučilišta u Zagrebu pa sve do odlaska u mirovinu u svojoj znanstvenoj problematici ...prvenstveno se posvetio proučavanju temeljnih zakonitosti ranog razvoja sisavaca. Posebnu pažnju posvetio je proučavanju uloge zametnih listića u ranoj embriogenezi. U okviru svoje znanstvene djelatnosti primjenjivao je mnoge dostupne znanstvene tehnike i metode od klasične deskriptivne histomorfološke analize i elektronske mikroskopije do histokemije i imunokemije. Dr. A. Švajger posebno se isticao na području eksperimentalne razvojne biologije vlastitom razrađenom metodom izolacije i mikromanipulacije te transplantacije ranih razvojnih stadija zametaka sisavaca na razini zametnih listića i njihovom eksplantacijom u in vivo i in vitro uvjete. U okviru zadanih znanstvenih zadataka davao je odgovore kao znanstvene rezultate na postavljena si pitanja o razvojnim procesima rane embriogeneze sisavaca. Stručna djelatnost dr. A. Švajgera bogata je i raznolika, posebice na području medicinske enciklopedistike. Visoku stručnu razinu znao je prenositi među suradnike i studente. Održanim brojnim javnim nastupima s tematikom užeg područja struke, općebioloških tema, povijesti medicine i Fakulteta te problematike liječničke etike pokazao se čovjekom široke opće i biomedicinske naobrazbe. U njegovu stručnu djelatnost, osim spomenutog, treba ubrojiti pisanje nastavnih tekstova, poglavlja u monografijama i priručnicima za poslijediplomsku nastavu te trajno usavršavanje liječnika.
Akademik Anton Švajger (1935. – 2002.) Bradamante, Želimir
Radovi Zavoda za znanstvenoistraživački i umjetnički rad u Bjelovaru,
2016
10
Journal Article
Peer reviewed
Open access
Academy Member Anton Švajger, doctor of medicine, was in his scientific work – from his arrival to the Institute of Histology and Embryology of the Faculty of Medicine of the University of Zagreb to ...his retirement – primarily dedicated to the study of fundamental rules in the early development of mammals. He paid special attention to the study of the role of embryonic germ layers leaves in early embryogenesis. Within the frame of his scientific activity, he applied many available scientific techniques and methods – from the classic descriptive histomorphological analysis and electronic microscopy to histochemistry and immunochemistry. Dr. Švajger was particularly prominent in the field of experimental embriology thanks to his personal method of the isolation, micromanipulation and explantation of early developmental stages of mammal in germ layers to in vivo and in vitro conditions. In the context of the set scientific tasks, he gave answers in the form of scientific results to the questions he posed himself relating to developmental processes in the early embryogenesis of mammals. Dr. Švajger’s professional activity was rather rich and diverse, in particular in the field of medical encyclopaedistics. He knew how to transfer the high level of knowledge to his associates and students. In numerous public speeches to the topics including the narrow field of his profession; general biological topics; history of medicine and of the Faculty; as well as problems related to medical ethics, he proved himself as a man of broad general education and specific knowledge in biomedicine. In addition to the aforesaid, his professional activity included writing curricular texts, chapters in monographs, and manuals for postgraduate students, as well as lifelong education of medical doctors.
We report the novel observation that a biphasic, parieto-visceral (PYS/VYS) yolk sac carcinoma can develop from the isolated epiblast of the pre-primitive streak rat embryo in a prolonged cultivation ...in vivo as a renal isograft. Late 7-day rat egg cylinders were dissected free of the ectoplacental cone and the Reichert's membrane. The middle segment of the cylinder, in which the embryonic and the extraembryonic cell layers partly overlap, were also removed. From the rest of the cylinder the 4 cell layers were isolated and transplanted separately under the kidney capsule of isogenic adult males. After 4 weeks the hypoblast was resorbed, the extraembryonic ectoderm gave rise to hemorrhagic cysts and trophoblastic giant cells, the extraembryonic (visceral yolk sac) endoderm formed benign cystic PYS/VYS tumors, and the epiblast developed into a benign teratoma. After prolonged (7-30 weeks) development of these teratomas as isografts, a malignant yolk sac carcinoma (YSC) developed in 45% of them. It destroyed the teratoma and the recipient's kidney, metastasized to peritoneum and other sites, and caused abundant ascites containing clustered tumor cells. The primary tumor was retransplantable subcutaneously as well as intraperitoneally, and displayed the characteristics of the mixed or biphasic PVYS carcinoma, with a progressive loss of the VYS component with time. Several data are apparently in favor of its origin by transdifferentiation rather than from undifferentiated cells.
We report the novel observation that a biphasic, parieto-visceral (PYS/VYS) yolk sac carcinoma can develop from the isolated epiblast of the pre-primitive streak rat embryo in a prolonged cultivation ...in vivo as a renal isograft. Late 7-day rat egg cylinders were dissected free of the ectoplacental cone and the Reichert’s membrane. The middle segment of the cylinder, in which the embryonic and the extraembryonic cell layers partly overlap, were also removed. From the
rest of the cylinder the 4 cell layers were isolated and transplanted separately under the kidney capsule of isogenic adult males. After 4 weeks the hypoblast was resorbed, the extraembryonic ectoderm gave rise to hemorrhagic cysts and trophoblastic giant cells, the extraembryonic (visceral yolk sac) endoderm formed benign cystic PYS/VYS tumors, and the epiblast developed into a benign teratoma. After prolonged (7–30 weeks) development of these teratomas as isografts, a malignant yolk sac carcinoma (YSC) developed in 45% of them. It destroyed the teratoma and the recipient’s kidney, metastasized to peritoneum and other sites, and caused abundant ascites containing clustered tumor cells. The primary tumor was retransplantable subcutaneously as well as intraperitoneally, and displayed the characteristics of the mixed or biphasic PVYS carcinoma, with a progressive loss of the VYS component with time. Several data are apparently in favor of its origin by transdifferentiation rather than from undifferentiated cells.
Halves of transversely or longitudinally cut primary ectoderm of the pre-primitive streak and the early primitive streak rat embryonic shield developed after 15â30 days in renal homografts into ...benign teratomas composed of various adult tissues, often in perfect organspecific associations. No clear difference exists in histological composition of grafted halves of the same embryonic ectoderm. The primary ectoderm of the pre-primitive streak rat embryonic shield grafted under the kidney capsule for 2 days displayed an atypical morphogenetic behaviour, characterized by diffuse breaking up of the original epithelial layer into mesenchyme. Some of these cells associated into cystic or tubular epithelial structures. The definitive ectoderm of the head-fold-stage rat embryo grown as renal homograft for 1â3 days gave rise to groups of mesenchymal cells. These migrated from the basal side of the ectoderm in a manner which mimicked either the formation of the embryonic mesoderm or the initial migration of neural crest cells. This latter morphogenetic activity was retained in the entire nejjral epithelium of the early somite embryo but was only seen in the caudal open portion of the neural groove at the 10- to 12-somite stage. The efficient histogenesis in grafts of dissected primary ectoderm and the atypical morphogenetic behaviour of grafted primary and definitive rat embryonic ectoderm were discussed in the light of current concepts on mosaic and regulative development, interactive events during embryogenesis and positioning and patterning of cells by controlled morphogenetic cell displacement.
Ultrastructure of elastic cartilage in the rat external ear Kostovic-Knezevic, L; Bradamante, Z; Svajger, A. (Zagreb Univ. (Yugoslavia). Faculty of Medicine. Inst. of Histology and Embryology)
Cell and tissue research,
01/1981, Volume:
218, Issue:
1
Journal Article
Peer reviewed
The structure of elastic cartilage in the external ear of the rat was investigated by transmission and scanning electron microscopy. The narrow subperichondrial, boundary zone contains predominantly ...ovoid cells rich in cell organelles: mitochondria, Golgi complex, granular endoplasmic reticulum and small (40--100 nm) vesicles. Scarce glycogen granules and bundles of 6--7 nm cytoplasmic filaments are also present. Deeper in the boundary zone, one or more cytoplasmic lipid droplets appear and cytofilaments become more abundant. Fully differentiated chondrocytes in the central zone of the cartilage plate resemble white adipose cells. They are globular and contain a single, large cytoplasmic lipid droplet. The cytoplasm is reduced to a thin peripheral rim; it contains a flattened nucleus, few cytoplasmic organelles and abundant, densely packed, cytoplasmic filaments. The intercellular matrix is very sparse. The pericellular ring consists of collagen fibrils about 20 nm in diameter and a proteoglycan cartilage matrix in the form of a "stellate reticulum". The complex of these two structures appears in the scanning electron micrographs as a a network of randomly oriented, ca 100 nm thick fibrils. Spaces between pericellular rings of matrix also contain thick elastic fibers or plates, apparently devoid of microfibrils. In scanning electron micrographs elastic fibers could be detected only in a few areas, in which they were not obscured by other constituents of the matrix. Immature forms of elastic fibers, oxytalan (pre-elastic) and elaunin fibers, were found in the perichondrial and boundary zones.
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