Whole embryo culture

After intraamniotic injection, acrolein is teratogenic to rats in vivo but not in vitro. When administered intraamniotically to the whole embryo culture system of the rat on day 13 of gestation, acrolein caused edema, hydrocephaly, open eyes, cleft palate, abnormal umbilical cord, and defects of the limbs and face (Slott and Hales 1986). Beauchamp etal. (1985) suggest that acrolein-associated teratogenicity is caused by acrylic acid, an acrolein metabolite. Acrylic acid injected into amniotic fluid of rats on day 13 of gestation produced a dose-dependent increase in the percent of fetuses with skeletal and other abnormalities (Beauchamp et al. 1985). 

Hunter ES III, Rogers EH, Schmid JE, Richard A (1996) Comparative effects of haloacetic acids in whole embryo culture. Teratology 54 57-64... 

A wide range of in vitro systems, ranging from whole embryo culture through organ and tissue culture to a variety of nonmammalian systems, has also been developed for the study of developmental toxicity. In vitro tests are useful in investigation of mechanisms of normal and abnormal... 

In Europe, the developmental toxicity testing (including teratogenicity) of new cosmetic ingredients is performed according to the Cosmetics Directive 76/768/EEC only alternatives leading to full replacement of animal experiments should be used. This chapter presents the three scientifically validated animal alternative methods for the assessment of embryotoxicity the embryonic stem cell test (EST), the micromass (MM) assay, and the whole embryo culture (WEC) assay. 

Piersma AH et al (2004) Validation of the postimplantation rat whole-embryo culture test in the international ECVAM validation study on three in vitro embryotoxicity tests. Altern Lab Anim 32 275-307... 

The implementation of animal test protocols in the 1980s has been accompanied by the development of a host of alternative methods to study adverse effects of chemicals on reproductive and developmental parameters. For example, rat whole embryo culture stems from the seventies (16), as does the rat limb bud organ culture (17) and rat limb bud and brain micromass was developed in the eighties (18). An elegant nonvertebrate alternative model used regeneration of polyps of Hydra atUnuata from dissociated cells (19). Animal-free in vitro alternatives include those employing the proliferation of a human embryonic palatal mesenchymal cell line (20), the attachment of a mouse ovarian tumor cell line (21), and the differentiation of a neuroblastoma cell line (22) and a embryonal carcinoma cell line (23). Various overviews of methods have been published over the years (24). The predictability of... 

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. 

New DA (1978) Whole-embryo culture and the study of mammalian embryos during organogenesis. Biol Rev Camb Philos Soc 53(1 ) 81-122... 

The Rat Whole Embryo Culture Assay Using the Dysmorphology Score System... 

Key words Rat whole embryo culture. Teratogenicity screening, Dysmorphology score system, Rat... 

Rodent whole embryo culture has been routinely used over the past three decades. Alone with the culture method, a score system developed by Brown and Fabro, called the total morphology score (TMS) system, is commonly used to evaluate the embryos (2). This method evaluates six developmental stages of a variety of... 

Since the method of rodent whole embryo culture has been well described by different groups (3-5) the methodology will be briefly reviewed, but the focus of this chapter is to describe DMS system in detail. 

The timed pregnant rats are used to sample gestation day (GD) 9 embryos on the day of the whole embryo culture (WEC) assay. The rats are typically shipped -GD4-5 and allowed to acclimate in the animal room for 4-5 days prior to initiating the culture experiment. 

Fujrnaga M et al (1988) Rat whole embryo culture an in vitro model for testing nitrous oxide teratogenicity. Anesthesiology 69 401-404... 

Augustine-Rauch KA et al (2004) A study of vehicles for dosing rodent whole embryo culture with non aqueous soluble compounds. Reprod Toxicol 18 391-398... 

Due to the specificity of toxicogenomic signatures, compounds may be classified based on common genes (or pathways) disrupted. In developmental toxicity testing, approaches may be used for classification between (1) toxic and nontoxic exposures and/or (2) classes of chemical compounds. To date, most classification studies have been conducted in alternative developmental systems (i.e. stem cells, zebrafish, whole embryo culture) due to the size of material and experimental groups needed. In a series of studies by... 

Robinson JF et al (2012) A comparison of gene expression responses in rat whole embryo culture and in vivo time-dependent retinoic acid-induced teratogenic response. Toxicol Sci 126(l) 242-254... 

Robinson JF et al (2010) Embryotoxicant-specific transcriptomic responses in rat postimplantation whole-embryo culture. Toxicol Sci 118 675-685. doi kfq292 (pii)10.1093/ toxsci/kfq292... 

In 2007, the DART committee held a workshop on alternative assays, which was followed up by a workshop held at the European Teratology Society Annual Meeting in 2009. These workshops focused on three alternative assays (1) whole embryo culture (WEC), (2) mouse embryonic stem cell tests (mESC), and (3) zebrafish. Each assay was presented and data from users were shared, and strengths and limitations were discussed. It should be noted that the WEC and mESC are validated by ECVAM as alternative embryotoxicity assays. Still, there are numerous research needs before even validated tests can achieve regulatory acceptance. The discussions, conclusions, and recommendations of the 2007 workshop were published by Chapin et al. (14). Bullet lists of next steps to move forward were defined for each assay (14) and are briefly summarized here ... 

Chapin R, Augustine-Rauch K, Beyer B, Daston G, Finnell R, Flynn T, Hunter S, Mirkes P, O Shea KS, Piersma A, Sandler D, Vanparys P, Van Maele-Fabry G (2008) State of the art in developmental toxicity screening methods and a way forward a meeting report addressing embryonic stem cells, whole embryo culture, and zebrafish. Birth Defects Res B Dev Reprod Toxicol 83 446-456... 

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