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Biomedical subjects

Z Bradamante

Publications and source records attributed to Z Bradamante.

11 recordsLinked to original sources
PubMed1991

Neural growth factor inhibits the growth of rat egg-cylinders cultured in vitro.

Rat egg-cylinders at the primitive streak stage were grown in modified organ culture for 2 weeks using a chemically defined medium. Differentiation of the epidermis and cartilage was comparable to that in fully serum-supplemented medium, whereas neuroblasts were very scarce. In explants treated either with bovine serum albumin or transferrin, neuroblasts were observed, whereas the addition of NGF did not improve neuroblast differentiation. On the contrary, NGF impaired growth and tissue differentiation when compared with explants grown in serum-free medium.

Animals↗
PubMed1991

Differentiation of the secondary elastic cartilage in the external ear of the rat.

The cartilage in the external ear of the rat belongs to the group of secondary cartilages and it has a unique structural organization. The chondrocytes are transformed into typical adipose cells, the proteoglycan cartilage matrix is reduced to thin capsules around the cells and the rest of the extracellular matrix is occupied by a network of coarse elastic fibers. It appears late in development (16-day fetus) and needs more than one month for final development. The differentiation proceeds in several steps which partly overlap: the appearance of collagen fibrils, elastin fibers, the proteoglycan matrix, and the adipose transformation of chondrocytes. The phenotype of this cartilage and the course of its differentiation are very stable, even in very atypical experimental environmental conditions. The only exceptions are explants in organ culture in vitro and perichondrial regenerates. In these conditions the development of elastic fibers is slow and poor while the production of the proteoglycan matrix is abundant. The resulting cartilage then displays structural characteristics of hyaline cartilage rather than those of the initial elastic one.

Animals↗
PubMed1986

On the ultrastructure of the developing elastic cartilage in the rat external ear.

Selected ultrastructural features of chondrocytes and the extracellular matrix in the developing elastic cartilage of the external ear were studied in rat fetuses and young animals. The cytoplasmic lipid droplets were first observed in the 19-day fetus. They increase in number and size during the first post-natal week. The elastogenesis proceeds in the sequence: oxytalan fibers (17-day fetus), elaunin fibers (1-day rat), elastic fibers (5-day rat). Intermediary stages between the randomly oriented individual microfibrils and bundles of microfibrils (oxytalan fibers) were also observed.

Animals↗
PubMed1981

Ultrastructure of elastic cartilage in the rat external ear.

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.

Animals↗
PubMed1981

Morphogenetic behaviour of the rat embryonic ectoderm as a renal homograft.

Halves of transversely or longitudinally cut primary ectoderm of the pre-primitive streak and the early primitive streak rat embryonic shield developed after 15-30 days in renal homografts into benign teratomas composed of various adult tissues, often in perfect organ-specific 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 1-3 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 neural 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.

Animals↗
PubMed1980

The role of epithelial collagen and proteoglycan in the initiation of osteogenesis by avian neural crest cells.

Osteogenesis was inhibited when mandibular processes from 3 1/2-day-old embryos were cultured in BUdR, LACA, alpha, alpha'-Dipyridyl, 4-Methylumbelliferone, and 4-Methylumbelliferyl-beta-D-glucoside or beta-D-xyloside. Mandibular processes were then cultured in the test substances for 3 days, enzymatically separated into their epithelial and ectomesenchymal components, combined with mandibular components from untreated embros, and either organ-cultured or grafted to chorioallantoic membranes of host embryos. Osteogenesis was inhibited when treated epithelium, but not when treated ectomesenchyme, was present in the tissue recombinations. Analysis of the known action of these inhibitors indicates that proliferation, hydroxylation of collagen, and synthesis of proteoglycans by epithelial cells are all necessary components of this osteogenic epithelial-ectomesenchymal interaction.

2,2'-Dipyridyl↗
PubMed1977

Pre-elastic (oxytalan) fibres in the developing elastic cartilage of the external ear of the rat.

During chondrogenesis in the external ear of the rat oxytalan fibres precede the appearance of mature elastic fibres by 6-7 days. The spatial distribution of oxytalan fibres in fetal and neonatal pre-cartilage corresponds to that of the elastic fibres in mature cartilage. These findings support the hypothesis that oxytalan fibres in the pre-cartilage of the external ear of the rat are pre-elastic in nature.

Age Factors↗