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Biomedical subjects

K Illmensee

Publications and source records attributed to K Illmensee.

At least 37 records · Page 2Linked to original sources
PubMed1983

Thymus differentiation and T-cell specificity in nu/nu +/+ mouse aggregation chimaeras.

Thymus development and T cell differentiation were studied in mouse chimaeras produced by aggregating pre-implantation embryos of thymus-deficient nude BALB/c (nu/nu) and wild-type C57BL/6 (+/+) mice and vice versa. Chimaeras showed mosaic distribution of skin and coat pigmentation, of hair follicles, of glucosephosphate isomerase within all tested organs and of lymphocytes expressing the different major transplantation antigens (H-2). When tested for their capacity to generate vaccinia virus-specific and self-H-2 specific cytotoxic T cells, all chimaeras of BALB/c (nu/nu) H-2d in equilibrium C57BL/6 (+/+) H-2b type generated T cells of one or both parental origins that were specific for virus and for self-H-2 of the +/+ (H-2b) type only. In contrast, some BALB/c (+/+) H-2d in equilibrium C57BL/6 (nu/nu) H-2b chimaeras generated vaccinia virus-specific cytotoxic T cells specific for either H-2d (+/+) type or for H-2b (nu/nu) type. These asymmetrical results can be interpreted to indicate the following: (i) The +/+ thymus part alone is functional, but because of asymmetrical cross-reactivities of anti-self-H-2 specificities, the observed T cell restriction phenotypes differ. (ii) Both nu/nu and +/+ thymus parts are functional but immune response defects may be exaggerated in such chimaeras producing unexpected non-responsiveness to vaccinia virus linked to H-2d in H-2b (+/+) in equilibrium H-2d (nu/nu).

Animals↗
PubMed1983

Enzyme activity profiles in mouse teratocarcinomas. A quantitative ultramicroscale analysis.

Nine tumour lines with different developmental capacities were derived from spontaneous as well as from one induced teratocarcinoma: three teratocarcinoma-derived rhabdomyosarcomas TDR 602, TDR 694, and TDR 114; two teratocarcinoma-derived neuroblastomas TDN 2151 and TDN 2283; two teratocarcinoma-derived endodermal tumours TDE 274 and TDE 113; one multipotential teratocarcinoma OTT 2289, and one undifferentiated teratocarcinoma OTT 2158. Quantitative analyses of ten catabolic enzymes, i.e. alkaline and acid phosphatase, alpha- and beta-galactosidase, alpha- and beta-glucosidase, alpha-mannosidase, alpha-fucosidase, beta-glucuronidase, and hexosaminidase were carried out at the 20-cell level, and specific enzyme activity profiles were established for each of the tumour lines studied. These profiles may be used for the biochemical identification of a tumour type at the single cell level in addition to morphological and biological criteria.

Acid Phosphatase↗
PubMed1983

Formation of cytoskeletal elements during mouse embryogenesis. IV. Ultrastructure of primary mesenchymal cells and their cell-cell interactions.

The ultrastructure of the day 8.5 mouse embryo has been studied by transmission electron microscopy, with special emphasis on the primary mesenchymal cells and their interaction with cells of the embryonic ectoderm and the proximal endoderm. The organization of the two polar epithelial cell layers (embryonic ectoderm and proximal endoderm), the isolated cells of the distal endoderm and the primary mesenchymal cells is described. Primary mesenchymal cells are different from embryonic ectoderm cells, from which they are derived, not only by the absence of desmosomes and intermediate-sized filaments of the cytokeratin type but also by their variable morphology not exhibiting stable polar architecture, and their numerous cytoplasmic processes which make contacts with the basal lamina of the ectoderm, the basal cell surface of the proximal endoderm, and other mesenchymal cells. Over most of the embryo the embryonic ectoderm is covered by a typical basal lamina, except for certain regions that are frequently characterized by cytoplasmic projections ("blebs') from the basal cell surface membrane. In contrast, the basal surface of the proximal endoderm is not covered by a continuous basal lamina and reveals mushroom-like protrusions of the cortical cytoplasm. Junctions between primary mesenchymal cells are numerous and include adhaerens-type formations of various sizes as well as gap junctions. Occasionally, a special type of junction between mesenchymal cells and embryonic ectoderm has been found, resulting in local interruptions of the basal lamina. The observations are discussed in relation to possible mechanisms of mesoderm formation and the drastic changes of cell character that accompany this process, including cytoskeletal changes such as the disappearance of cytokeratin filaments and the expression of vimentin.

Animals↗
PubMed1982

Immunohistochemical localization of mouse testis-specific phosphoglycerate kinase (PGK-2) by monoclonal antibodies.

Monoclonal antibodies against mouse testis-specific phosphoglycerate kinase (PGK-2) were produced in order to determine immunohistochemically the onset of PGK-2 synthesis in the germinal epithelium of the mouse. PGK-2 was detected in testis sections in spermatids as early as stage 12 and in spermatozoa, but not in earlier stages of spermatogenesis nor in any somatic cells of the testis. During ontogeny, PGK-2 appears within the testis at day 30 post-partum, concomitant with spermatids entering the maturation phase. All three allelic isozymes PGK-2A, -2B, and -2C were detected equally by the monoclonal antibody in testis sections of several inbred mouse strains, each of which expresses a specific PGK-2 variant. Moreover, the monoclonal antibody against mouse PGK-2 reacted with heterologous sperm-specific PGK from rat, rabbit, and bull and, therefore, may serve as a useful immunochemical marker for mammalian spermatogenesis.

Aging↗
PubMed1982

Tissue preference and differentiation of malignant rat x mouse hybrid cells in chimaeric mouse fetuses.

Mouse teratocarcinoma cells (OTT6050) deficient for thymidine kinase were fused with rat hepatoma cells ( Fu5AH ) deficient for hypoxanthine phosphoribosyltransferase using inactivated Sendai virus. The hybrid cells were selected and cultured in the presence of HAT medium. A clonally established hybrid cell line ( As3 ), which in addition to its mouse genome contains several rat chromosomes, expresses rat specific enzyme variants and produces large primarily undifferentiated tumors, with some hepatoma characteristics in athymic nude mice. To reveal the in vivo developmental potential of these cells and to determine whether, under different experimental conditions, they are capable of participating in tissue differentiation, the As3 cells were injected into mouse blastocysts from the C57BL/6 strain. The experimental blastocysts were then transferred into the uteri of pseudopregnant foster mothers to allow further development. From a total of 212 blastocysts transplanted, 61 fetuses developed and were analysed for As3 contributions between the 10th and 18th day of gestation. Four fetuses at day 18 showed hybrid cell participation in their livers and a few organs of only endo-mesodermal origin, as judged from the presence of rat-specific enzyme variants. The enzymes were organ-specifically expressed (e.g., lactate dehydrogenase) or appeared newly during in situ differentiation while being absent in the original hybrid cells (e.g., glycerol-3-phosphate dehydrogenase). During short in vitro culture of the chimaeric organs, it was possible to select for the hybrid cells which reverted to an enzyme pattern simiar to but not identical with the As3 cell line and different to that observed in situ.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Experimental genetics of the mammalian embryo.

Recent progress in experimental mouse embryology has provided new approaches to the genetic manipulation of the mammalian embryo. The production of uniparental embryos enables one to compare maternal and paternal gene activity during development, to study the biological consequences of homozygosity of mutant genes, and to further elucidate the unsolved problem of X chromosome inactivation. Transplantation of nuclei from somatic cells into mouse eggs is considered the most vigorous functional test for the developmental capacity of the nuclear genome and provides a bioassay for the study of possible genomic changes during cellular differentiation. Transplantation of cloned eukaryotic genes into mouse eggs will permit the molecular and genetic analysis of their integration and regulation during development and, eventually, their germ line transmission as new heritable elements.

Animals↗
PubMed1982

Full-term development after transplantation of parthenogenetic embryonic nuclei into fertilized mouse eggs.

Diploid parthenogenetically activated oocytes were obtained after gonadotropin-induced ovulation of virgin females of the LT/Sv (LT) inbred mouse strain. These oocytes cleave spontaneously and develop into blastocysts which implant in the uterus but die within a few days. We examined the developmental potential of nuclei from parthenogenetic embryos after transplantation into fertilized eggs. The inner cell mass (ICM) and trophectoderm (TE) of LT parthenogenetic blastocysts were mechanically isolated and dissociated into single cells. Their nuclei were then injected into fertilized C57BL/6J eggs from which the male and female pronuclei were removed. Of 94 eggs injected with TE cell nuclei, 4 embryos developed to the morula stage; all 4 showed abnormalities and subsequently became arrested in development. Enzyme analysis of these embryos revealed that TE cell nuclei could neither independently initiate or support preimplantation development. However, of 54 eggs injected with nuclei from ICM cells, 3 morulae and 3 blastocysts developed and enzyme analyses of them confirmed that the preimplantation development of 2 embryos was supported by transplanted parthenogenetic nuclei. In another experimental series, 3 morulae and 4 blastocysts developed from 107 eggs injected with ICM nuclei and were transferred to uteri of foster mothers to ascertain their postimplantation development. Four female offspring were born and all of them showed a diploid karyotype and expressed enzyme activity of only the LT genotype. One female proved to be fertile and transmitted the parthenogenetic genome to the next generation. These results demonstrate that the nucleus from LT parthenogenetic blastocysts contains a complete genome necessary to support development of an adult mouse. Therefore, the early postimplantation death of parthenogenetic embryos does not seem to be related to an aberrant genotype but rather to undefined mechanisms associated with fertilization and normal morphogenetic processes.

Animals↗
PubMed1982

Formation of cytoskeletal elements during mouse embryogenesis. III. Primary mesenchymal cells and the first appearance of vimentin filaments.

The cytoskeletal composition of the 'primitive streak' stage of mouse embryos, i.e. at late day 8 ('day 8.5') of gestation, has been examined by electron microscopy, using thin sections of fixed and embedded embryos, and by immunofluorescence microscopy, using cryostat sections of frozen embryos. At this stage primary mesenchymal cells are observed in the posterior part of the embryo which seem to migrate toward the anterior region. For most of the embryo, these mesenchymal cells are separated from the embryonic ectoderm by a continuous basal lamina. Frequently mesenchymal cells form cytoplasmic projections many of which make contact with this basal lamina, with surfaces of proximal endoderm cells, or with other mesenchymal cells. Primary mesenchymal cells contain sparse individual intermediate-sized filaments (IF), but closely packed IF bundles as they occur as tonofibrils in both embryonic epithelia, ectoderm and proximal endoderm, have not been found. Mesenchymal cells also can form junctions of the fascia adhaerens-type but appear to be devoid of desmosomes. Antibodies to cytokeratins reveal strong fibrillar fluorescence in cells of the proximal endoderm and weak, predominantly subapical staining in embryonic ectoderm. Correspondingly, antibodies to desmoplakins, the major proteins of the desmosomal plaque, show punctate fluorescence in both embryonic epithelia. These epithelial cells are not significantly stained with antibodies to other IF proteins such as vimentin and desmin. However, antibodies to vimentin show positive fluorescence, often in fibrillar tangles, in primary mesenchymal cells which in turn are negative with cytokeratin and desmin antibodies. This first detection of expression of vimentin in embryogenesis has been confirmed by two-dimensional gel electrophoresis of cytoskeletal proteins from 35S-methionine-labelled embryos. The observations indicate that during embryogenesis synthesis of vimentin occurs, for the first time, in the primitive streak stage and is restricted to the primary mesenchymal cells. Concomitantly, these cells cease to produce cytokeratins and desmoplakin. Possible mechanisms effective in this rapid change from epithelial to mesenchymal character, i.e. from cytokeratin IF to vimentin IF, are discussed.

Animals↗
PubMed1982

The expression of X-linked phosphoglycerate kinase in the early mouse embryo.

During early mouse embryogenesis, the activity of X-chromosomally linked maternal and paternal phosphoglycerate kinase (PGK-1) alleles was determined using electrophoretic separation of their gene products and a sensitive fluorometric enzyme assay. In the embryos collected from females homozygous for PGK-1b mated with PGK-1a males and vice versa, the paternally derived allozyme was first detected after implantation on day 6. Expression of the maternally inherited allele was studied in embryos from females heterozygous for PGK-1b and PGK-1a. From day 1 to day 4, the embryos maintained a constant ratio of enzyme activity of PGK-1B to PGK-1A. Prior to implantation of the embryos between day 4 and day 5, the activity ratio of the two PGK-1 allelic variants changed significantly due to the first appearance of newly synthesized PGK derived from the maternally inherited allele. Our data demonstrate a temporal difference in the onset of PGK synthesis depending on whether this particular gene product is of maternal or paternal origin. Therefore, we conclude that the maternal PGK-1 locus is already activated during late preimplantation development whereas the paternally inherited gene locus remains silent at the preimplantation stage but is subsequently expressed at approximately the time of X-chromosomal inactivation.

Animals↗
PubMed1981

Formation of cytoskeletal elements during mouse embryogenesis. II. Epithelial differentiation and intermediate-sized filaments in early postimplantation embryos.

Following our study on the expression of cytokeratin filaments in preimplantation mouse embryos [30], we have examined the organization of cytoskeletal elements in early postimplantation embryos up to day 8 of gestation, employing electron microscopy, immunofluorescence microscopy an two-dimensional gel electrophoresis of cytoskeletal proteins labelled by incorporation of 35S-nethionine. The characteristic epithelia formed by the embryonic ectoderm and proximal (visceral) endoderm present well-developed junctional complexes and various differentiated membrane structures. Several apical differentiations of the proximal endodermal cells, such as brush border-like microvilli, the endocytotic labyrinthum, and the supranuclear vacuoles resemble the organization of epithelial cells of the ileum of neonatal mammals. Both embryonic epithelia show typical desmosomes and attached intermediate sized filaments of the cytokeratin type. Other types of intermediate-sized filaments, such as vimentin and desmin filaments, have not been detected in any of the cells of embryos of days 6 and 7, but filaments of the vimentin type can be seen, by immunofluorescence microscopy, late in day 8 in certain cells located in the forming mesoderm. Gel electrophoresis has further revealed that the major cytoskeletal proteins synthesized during days 6-8 in both extraembryonic and embryonic tissue are similar to those characteristic of preimplantation blastocysts and include a major polypeptide corresponding to cytokeratin A described in some internal organs of adult rodents. By the same techniques, synthesis of another cytoskeletal proteins vimentin, has first been found late in day 8. It is concluded that early postimplantation embryonic development, up to mesoderm formation, is characterized by the exclusive presence, in both embryonic ectoderm and proximal endoderm, of differentiated epithelial cells containing desmosome-cytokeratin filament complexes and that other types of intermediate-sized filaments are not yet expressed.

Animals↗