Embryo culture application

Therefore, a validation exercise with a variety of compounds with unknown mechanisms of developmental toxicity has only limited value if only used to derive an overall predictability rate of a single assay. It is more useful to elucidate the applicability domain of the assay in terms of the mechanisms of development covered, and to validate that aspect by testing compounds that do or do not affect the applicability domain. For single end point assays such as specific receptor activation assays, this exercise is relatively straightforward. For more complex assays such as those involving embryonic cell differentiation, the understanding of the applicability domain is more complex, as extensive research with the embryonic stem cell test has learned (27, 47). Whole embryo cultures are probably more straightforward in terms of applicability domain as they involve the entire embryo in a limited window of development, but such assays are complex and not animal free. 

Due to the limited applicability of in silico SAR approaches for developmental toxicity, there is more reliance on in vitro screening. From what has been publicly disclosed, it is evident that the four in vitro tests used for industrial screening are chick embryonic neural retina (CENR) micromass culture, whole embryo culture (WEC, rodent or rabbit), and mouse embryonic stem cells (EST). Recently, there has been significant interest within the pharmaceutical industry in the use of zebrafish for developmental toxicity testing,30 but because this aspect is in its infancy, there is little that has been publicly disclosed except limited abstracts and slide decks at several workshops.31 Although reviewed in considerable detail elsewhere,30-32 36 each test will be briefly compared and contrasted here. 

The results obtained so far clearly demonstrate that in-vitro oocyte maturation (TVM) of embryos obtained from ovaries of slaughtered cows, subsequent in-vitro fertilization (IVF) of these, in-vitro embryo culture (IVC) and embryo transfer process is a possible option for generating specific cattle genotypes for specific production systems in Eastern Afiica. However, there is need for fine tuning of the IVM, IVF and IVC protocols for the local zebu breeds. Planned application of combinations of these technologies would deliver the desired genotypes and commercial business approaches are needed to deliver this technology beyond the current laboratory trial. Ovum pick up (OPU), if embraced, would even make the process much more economically and ethically attractive. 

Application of ABA to immature wheat embryos prevents embryonic germination, while embryo culture without ABA results in precocious germination [23]. Incubation of immature embryos in ABA also causes the early accumulation of proteins that are characteristic of later stages of embryo maturation [22]. Some of the maturation proteins have been identified and these include wheat germ... 

Initially plant cell culture techniques progressed more slowly than those for animal cells, as did procedures for the isolation of plant cell organelles. Technical difficulties have now largely been overcome and culturing plant embryos has now found important commercial applications. 

Ozolins TR, Oglesby LA, Wiley MJ, et al. In vitro murine embryotoxicity of cyclophosphamide in embryos co-cultured with maternal hepatocytes development and application of a murine embryo-hepatocyte co-culture model. Toxicology. 1995 102(3) 259-274. 

The most important fields of research for industrial applications, plant cell tissue and organ cultures are clonal propagation and secondary metabolite production. Plants cultivated in vitro have great changes in their morphological features, from cell tissue to differentiated embryo, roots, shoots or plantlets. 

Thus, some endogenous small molecular compounds that are able to mimic the biological effect of the natural neurotrophic factors, or to stimulate their synthesis and secretion, might be promising candidates for pharmaceutical agents of various neurodegenerative diseases. Sex hormones, thyroid hormones, vitamin D and their derivatives are already known to affect survival and differentiation of dissociated mouse embryo brain in cultures or in cultured rat septal neurons. However, application of these hormones to patients with normal hormone function... 

Embryonic stem (ES) cells are isolated from the inner cell mass (ICM) of a blastocyst stage embryo, which consists of a layer of trophoblast cells lining the ICM and blastocoel or blastocyst cavity. The ICM and trophoblast cells give rise to the embryo proper and extra-embryonic tissue, respectively. Thirthy years ago the in vitro culture of mouse ES (mES) cells was first described (Evans and Kaufman, 1981 Martin, 1981) and later in 1998 also human ES (hES) cells were derived (Thomson et al. 1998). ES cells are characterized by the unique properties of unlimited self-renewal without senescence and pluripotency. The latter infers that ES cells give rise to all cell types of the body. These specific properties led to the great scientific interest in ES cell either for their potential medical applications or as models to address more fundamental questions in development. 

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