Search PubMed⌕ Search

Biomedical subjects

J Rossant

Publications and source records attributed to J Rossant.

At least 181 records · Page 10Linked to original sources
PubMed1980

Intrinsic and extrinsic factors affecting the viability of Mus caroli x M. musculus hybrid embryos.

Interspecific hybrids between M. musculus and M. caroli, a wild species of mouse, were produced by artificial insemination, although the species do not normally interbreed. However, the success rate was low, with many embryos dying at various stages of pregnancy. Hybrid embryos were retarded in comparison with either parent species from the earliest stages of development, suggesting that intrinsic problems of genomic incompatibility play a major role in poor hybrid survival. However, failure of normal embryo-uterine interactions may also be important, since M. caroli x M. caroli embryos transferred to the M. musculus uterus also failed to survive to term. It is suggested that a maternal immune response to antigens on the foreign trophoblast may be involved.

Animals↗
PubMed1979

Investigation of the fate of 4-5 day post-coitum mouse inner cell mass cells by blastocyst injection.

Two distinct patterns of chimaerism were found in conceptuses produced by injecting dissociated 4.5-day inner cell mass cells into genetically dissimilar blastocysts. Pattern 1: donor cells were found in the endoderm layer of the visceral yolk sac, but not in the adjacent mesoderm layer of this organ or in the foetus itself. Pattern 2: donor cells were found in the mesoderm layer of the visceral yolk sac and/or foetus, but never in the yolk-sac endoderm as well. Primitive endoderm cells of donor inner cell masses are responsible for the first pattern and primitive ectoderm cells for the second. These results, together with those of previous studies, suggest that the entire foetus, including its endodermal components, is formed from the primitive ectoderm, and that primitive endoderm forms only extra-embryonic endoderm of the conceptus.

Animals↗
PubMed1978

Effect of implantation delay on transfer of rat embryos to mice.

Rat and mouse blastocysts were transferred to the uteri of ovariectomized mice, maintained by progesterone for a few days and induced to implant by oestradiol administration. Mouse implantation sites contained normal embryos; all rat embryos were retarded, although some had developed to the egg-cylinder stage.

Animals↗
PubMed1978

Investigation of the potency of cells from the postimplantation mouse embryo by blastocyst injection: a preliminary report.

Chimaeric conceptuses have been produced by injection of 5 1/2-and 6 1/2-day extra-embryonic ectoderm and 5 1/2-day embryonic and extra-embryonic endoderm into 3 1/2-day mouse blastocysts. Extra-embryonic ectoderm cells contributed only to the ectoplacental cone and/or trophoblast giant cell fractions, reflecting the probable trophectoderm origin of these cells. Proximal (visceral) endoderm cells overlying both the embryonic and extra-embryonic ectoderm contributed cells only to the endoderm of the visceral yolk sac, indicating that the definitive embryonic endoderm has not formed by 5 1/2 days p.c.

Animals↗
PubMed1977

[Crohn's disease].

Explore the source record for details and available documents.

Crohn Disease↗
PubMed1977

Properties of extra-embryonic ectoderm isolated from postimplantation mouse embryos.

Extra-embryonic ectoderm isolated from the mouse embryo as late as 81/2 days post coitum can form cells with the morphological characteristics of trophoblast giant cells both in ectopic sites and in vitro. This similarity to the properties of ectoplacental cone tissue provides further support for the postulated common origin of both tissues from the trophectoderm of the blastocyst.

Animals↗
PubMed1976

Postimplantation development of blastomeres isolated from 4- and 8-cell mouse eggs.

Blastomeres isolated from 4- and 8-cell mouse eggs were inserted into empty zonae and transferred to the oviduct. The products of both types of blastomere were capable of inducing decidual formation. One implant produced by an isolated blastomere from a 4-cell egg contained a small, retarded embryo at 5 1/2 days but most decidua from blastomeres of either 4- or 8-cell eggs contained only a few trophoblast giant cells. It is suggested that this lack of totipotency is due to insufficient cells being present at cavitation rather than restriction in developmental potential.

Animals↗
PubMed1976

The effect of short-term labelling in (3H) thymidine on the viability of mouse blastomeres: alone and in combination with unlabelled blastomeres.

A method of labelling 8-cell-stage mouse blastomeres with [3H]thymidine is described, which allows them to be followed to the late blastocyst stage and is compatible with normal postimplantation development. However, the [3H]thymidine does affect the postimplantation vigour of the cells when placed in competition with unlabelled cells in blastomere aggregates. This suggests that caution should be used in interpreting results using [3H]thymidine as a label for early mammalian cells.

Animals↗
PubMed1976

Investigation of inner cell mass determination by aggregation of isolated rat inner cell masses with mouse morulae.

Inner cell masses (ICMs) dissected from 4 1/2-day rat blastocysts were aggregated with 2 1/2-day mouse morulae. Successful aggregates formed blastocysts in vitro and morphologically normal 5 1/2-day conceptuses in the mouse uterus. Immunofluorescent analysis of these conceptuses revealed that rat cells were only present in the embryonic ectoderm and endoderm and never in the trophectoderm derivatives, although rat trophoblast did develop in the mouse uterus in various control experiments. The single-cell resolution of this technique extends the results obtained from aggregating mouse ICMs with mouse morulae and provides strong evidence that ICM cells, although not overtly differentiated, are determined by the blastocyst stage.

Animals↗
PubMed1975

Investigation of the determinative state of the mouse inner cell mass. I. Aggregation of isolated inner cell masses with morulae.

Inner cell masses (ICMs) were dissected from 3 1/2- and 4 1/2-day blastocysts and cultured in contact with 2 1/2-day morulae. Blastocysts and morulae were homozygous for different electrophoretic variants of the enzyme glucose phosphate isomerase (GPI). Aggregation of ICMs and morulae was observed, and such aggregates were able to form blastocysts in vitro and morphologically normal foetuses in utero. GPI analysis of these conceptuses revealed that most were chimaeric. However, donor ICM-type isozyme was only detected in the embryonic and extra-embryonic fractions of the chimaeras and never in the trophoblastic fraction. Thus, ICM cells appear unable to form trophoblast derivatives even when exposed to 'outside' conditions as experienced by developing trophoblast cells. This is evidence that ICM cells, although not overtly differentiated, are determined by 3 1/2 days.

Animals↗
PubMed1975

Investigation of the determinative state of the mouse inner cell mass. II. The fate of isolated inner cell masses transferred to the oviduct.

Inner cell masses (ICMs) were dissected from 3 1/2- and 4 1/2-day mouse blastocysts and inserted into empty zonae before transfer to the oviducts of pseudopregnant mice. The ICMs survived in the oviduct for at least 2 days with little evidence of reduction in cell number. After 1 day, isolated 3 1/2-day ICMs were still viable, since they could form chimaeras when injected into 3 1/2-day blastocysts. However, no evidence of trophoblast formation could be detected in any of the isolated ICMs, despite exposure of some of their cells to 'outside' conditions. This is further evidence that ICM cells, although not overtly differentiated, are determined by 3 1/2 days. Although no trophoblast was formed, 3 1/2-day ICMs formed an outer endoderm layer after 1 day in the oviduct, as judged by light and electron microscopical evidence. It is suggested that cell position may be important in endoderm differentiation.

Animals↗
PubMedDate not supplied

Cell lineage-specific undermethylation of mouse repetitive DNA.

Several distinct cell lineages are established during mouse embryogenesis. The trophectoderm and primitive endoderm give rise to extraembryonic structures alone, while the primitive ectoderm becomes the fetus proper. Recent studies suggest that the levels of DNA modification are lower in inactive X chromosomes from extraembryonic tissues than in embryonic and adult somatic tissues. Using HpaII/MspI isoschizomers, Southern blots and cloned probes, we show here that repetitive DNA sequences from all derivatives of the two extraembryonic lineages, trophectoderm and primitive endoderm, are substantially undermethylated compared with primitive ectoderm derivatives. This contrasts with the highly methylated state of these repetitive elements observed in adult somatic tissues. Specific demethylation or inhibition of de novo methylation, or a combination of both mechanisms, may be involved. These findings suggest that elements of gene regulation dependent on DNA modification may be different in extraembryonic cell lineages.

Animals↗
PubMedDate not supplied

Clonal origin of haematopoietic colonies in the postnatal mouse liver.

The liver of the neonatal mouse continues to show haematopoietic activity for up to 2 weeks after birth and morphological analysis has shown that this activity becomes focused in discrete haematopoietic colonies by the end of the first week postnatal. Furthermore, each colony contains cells of one haematopoietic lineage only, that is, erythroid, myeloid or pre-B-lymphoid cells. This pattern of differentiation suggests that each colony is derived from a single committed precursor cell, which, if true, would represent the first demonstration of non-mixed haematopoietic colonies in normal development and would provide a useful system for studying the factors affecting the clonal diversity of haematopoietic stem cells and their lineage-committed progeny. Here we have analysed the haematopoietic foci in the liver of neonatal mouse chimaeras, using a newly developed ubiquitous in situ cell marker system which clearly demonstrates the clonal origin of these colonies.

Animals↗