The Experts below are selected from a list of 21 Experts worldwide ranked by ideXlab platform

Fox R. R. - One of the best experts on this subject based on the ideXlab platform.

  • Histologic characterization of renal tumors (nephroblastomas) induced transplacentally in IIIVO/J and WH/J rabbits by N-ethylnitrosourea.
    2026
    Co-Authors: Hard G. C., Fox R. R.
    Abstract:

    The histologic features of 63 renal tumors induced in 39 rabbits of two partially inbred strains, IIIVO/J and WH/J, by transplacental exposure to N-ethylnitrosourea (ENU) were analyzed. All tumors in the series conformed to nephroblastoma, permitting the establishment of histologic standards for this neoplasm in the rabbit as well as observations on tumor progression. Essentially, nephroblastoma proved to be predominantly an epithelial tumor identifying with Metanephrogenic Blastema, which was presumed to be the tissue of origin during fetal development. The outstanding features comprised clusters or sheets of undifferentiated Blastemalike tissue and differentiation along the epithelial pathway into tubular profiles and structures suggestive of primitive, nonvascularized glomeruli. The latter were frequently of a complex nature, with a papillary configuration. On the other hand, no definitive evidence of bipotential differentiation into malignant secondary mesenchyme was found, there being no recognizable areas of fibrosarcomatous elements or specialized connective tissue such as smooth or striated muscle, adipose tissue, cartilage, or osteoid. Mesenchymelike fascicular disposition of neoplastic cells between Blastemal clusters was an acquired feature seen in advanced tumors but not in small early lesions. By light microscopy alone it was not possible to determine whether this represented a conformational change of tumor cells or true bipotential differentiation into neoplastic secondary mesenchyme. However, the reticulin pattern was not characteristic of sarcoma. A conspicuous feature accompanying the growth and development of tumors was the magnitude of host fibrous reaction discernible only as a simple ramifying stroma in the earliest lesions but attaining impressive proportions both within and around the tumor with advancing age. Increasing collagen formation appeared to be associated with ischemic necrosis of tumor tissue. Other features of advanced tumors were the presence of discrete foci of differentiated tubular structures suggestive of mature medullary elements and small islands of squamoid differentiation. Metastases occurred only in rabbits of strain IIIVO/J, which had been subjected to a single dose of the carcinogen, representing an incidence in this subgroup of 25%. Nephroblastomas resulting from transplacental induction in IIIVO/J rabbits, particularly by single, high doses of ENU, appear to provide a suitable model for the predominant histologic form of the Wilms' tumor complex in man

P. Grasso - One of the best experts on this subject based on the ideXlab platform.

  • Nephroblastoma in the Rat: Histology of a Spontaneous Tumor, Identity With Respect to Renal Mesenchymal Neoplasms, and a Review of Previously Recorded Cases " 2
    2016
    Co-Authors: Gordon C. Hard, P. Grasso
    Abstract:

    ABSTRACT-The histology of a spontaneously occurring neo-plasm of the rat kidney conforming to a classification of nephro-blastoma is described and compared with that of N-nitrosodi-methylamine-induced renal mesenchymal tumors. This rat ne-phroblastoma was an encapsulated epithelioid neoplasm with a uniform histologic pattern. Clumps of densely crowded, hyper-chromatic cells frequently associated with central, well-differen-tiated ducts were supported by a less cellular, interconnecting stroma of loose areolar or mature fibrous connective tissue. Neoplastic cells were organized into primitive, ill-defined tubular formations. The neoplastic cell component strongly resembled Metanephrogenic Blastema. In contrast, the renal mesenchymal tumor was nonencapsulated and consisted of a heterogeneous mixture of connective tissue elements including fibroblast-like spindle cells, smooth muscle, and embryonic mesenchyme tha

Michal Zapletal A - One of the best experts on this subject based on the ideXlab platform.

  • EXPRESSION OF BCL-2 IN THE DEVELOPING KIDNEY OF HUMAN EMBRYOS AND FETUSES QUALITATIVE AND QUANTITATIVE STUDY
    1999
    Co-Authors: Václav Lichnovský A, Běla Erdösová A, Karla Punkt B, Michal Zapletal A
    Abstract:

    Twelve human embryos and fetuses aged of 7–30 weeks of intrauterinal life were examined to determine the expression of bcl-2 gene in the developing kidney. Tissue samples were routinely processed and three-step indirect immunohistochemical method was used for the detection of Bcl-2 protein. End-point cytophotometry was performed with computer-controlled microscope photometer with a scanning table and the mean relative absorbance of the final product of peroxidase reaction was determined and taken as a measure of Bcl-2 expression. The morphometric evaluation was carried out from the TV display using Weibel s universal hexagonal raster and we determined the relative volume of Bcl-2 positive structures in the various zones of the embryonal kidney. The aim of our research was mapping of the Bcl-2 occurrence in the developing kidney of human embryos and fetuses. The Bcl-2 protein is involved in the regulation of apoptosis and its effect is antiapoptotic. The highest Bcl-2 expression was proved in the cells of Metanephrogenic Blastema. The lower occurrence of Bcl-2 positive cells was demonstrated in proximal tubules anlages and it was almost on the borderline of detection in branches of ureteral bud. In the fetal period the marked Bcl-2 expression was maintained in the epithelial cells of proximal tubules anlages

Hard G. C. - One of the best experts on this subject based on the ideXlab platform.

  • Histologic characterization of renal tumors (nephroblastomas) induced transplacentally in IIIVO/J and WH/J rabbits by N-ethylnitrosourea.
    2026
    Co-Authors: Hard G. C., Fox R. R.
    Abstract:

    The histologic features of 63 renal tumors induced in 39 rabbits of two partially inbred strains, IIIVO/J and WH/J, by transplacental exposure to N-ethylnitrosourea (ENU) were analyzed. All tumors in the series conformed to nephroblastoma, permitting the establishment of histologic standards for this neoplasm in the rabbit as well as observations on tumor progression. Essentially, nephroblastoma proved to be predominantly an epithelial tumor identifying with Metanephrogenic Blastema, which was presumed to be the tissue of origin during fetal development. The outstanding features comprised clusters or sheets of undifferentiated Blastemalike tissue and differentiation along the epithelial pathway into tubular profiles and structures suggestive of primitive, nonvascularized glomeruli. The latter were frequently of a complex nature, with a papillary configuration. On the other hand, no definitive evidence of bipotential differentiation into malignant secondary mesenchyme was found, there being no recognizable areas of fibrosarcomatous elements or specialized connective tissue such as smooth or striated muscle, adipose tissue, cartilage, or osteoid. Mesenchymelike fascicular disposition of neoplastic cells between Blastemal clusters was an acquired feature seen in advanced tumors but not in small early lesions. By light microscopy alone it was not possible to determine whether this represented a conformational change of tumor cells or true bipotential differentiation into neoplastic secondary mesenchyme. However, the reticulin pattern was not characteristic of sarcoma. A conspicuous feature accompanying the growth and development of tumors was the magnitude of host fibrous reaction discernible only as a simple ramifying stroma in the earliest lesions but attaining impressive proportions both within and around the tumor with advancing age. Increasing collagen formation appeared to be associated with ischemic necrosis of tumor tissue. Other features of advanced tumors were the presence of discrete foci of differentiated tubular structures suggestive of mature medullary elements and small islands of squamoid differentiation. Metastases occurred only in rabbits of strain IIIVO/J, which had been subjected to a single dose of the carcinogen, representing an incidence in this subgroup of 25%. Nephroblastomas resulting from transplacental induction in IIIVO/J rabbits, particularly by single, high doses of ENU, appear to provide a suitable model for the predominant histologic form of the Wilms' tumor complex in man

Dana Kylarová - One of the best experts on this subject based on the ideXlab platform.

  • THE DETECTION OF MYC PROTEINS IN THE DEVELOPING HUMAN KIDNEY
    2004
    Co-Authors: Běla Erdösová, Filip Wagner, Dana Kylarová
    Abstract:

    The aim of our work was the detection of c- and N- myc proteins in the developing kidney of human fetuses espe-cially in the neogenous zone. These proteins being localized in nucleus and encoded by the cellullar oncogene myc function as transcriptional factors. Myc gene represents the key control gene in the course of cellular proliferation and differentiation. It also participates in the regulation of apoptosis and the origin of some cancers. Both proteins have been proved to be inevitable for proper nephrogenesis in mice. Considering the dearth of studies dealing with human embryonic tissues, we attempted to map the localization and spatiotemporal relations of the expression of these proteins during human nephrogenesis. In addition, issuing from our previous observations, we tried to compare their ways of expression with those of Bcl-2 (antiapoptotic effect) and Bax (proapoptotic function) proteins. Histologically normal kidneys were collected from eight human fetuses ranging from the 10th – 30th week of IUD. Tissue samples were fixed in methacarn and processed by routine paraffin technique. Standard indirect three-step immunohistochemical method was applied for the detection of N- and c-myc proteins. In the neogenous zone both proteins are markedly present in Metanephrogenic Blastema with declining intensity with the increasing age of fetus. Branches of ureteral bud are almost negative. Such localization is also typical for Bcl-2 protein whereas Bax positive cells are present mostly in branches of the ureteral bud. It is not clear if all these proteins collaborate in the course of regulation of apoptosis in human metanephros