There wasn’t much interest in studying the exposure of adult embryo to excess RA because we believed, although not confirmed that, once the anterior-most parts of the adult embryo have developed, RA acid might not have an obvious detrimental effect in preventing its development. Our assertion was however proven otherwise by Marshall et al., 1996, who demonstrated that RA treatment at later stages specifically leads to a ‘posteriorisation’ of rhombomeres (r) 2-3 to an r4-r5 identity. Moreover, treatment of pregnant mice or rats with excess RA leads to tetratogenic changes in the hindbrain (Morriss, 1972). Controlled exposure to retinoic acid (RA) is important for normal heart development, since excess RA is teratogenic, resulting in cardiac defects in humans and model organisms (Lammer et al., 1985; Mark et al., 2006; Pan and Baker, 2007). The tetratogic effect was found in majority of our test subjects. This could be due to poor judgment on our part as well as the formaldehyde in which the embryos were fixed because in most cases the eye development was not very clear. In other words, we could, as a results of error, classify a normal embryo as posterioriozed and that’s a source of
There wasn’t much interest in studying the exposure of adult embryo to excess RA because we believed, although not confirmed that, once the anterior-most parts of the adult embryo have developed, RA acid might not have an obvious detrimental effect in preventing its development. Our assertion was however proven otherwise by Marshall et al., 1996, who demonstrated that RA treatment at later stages specifically leads to a ‘posteriorisation’ of rhombomeres (r) 2-3 to an r4-r5 identity. Moreover, treatment of pregnant mice or rats with excess RA leads to tetratogenic changes in the hindbrain (Morriss, 1972). Controlled exposure to retinoic acid (RA) is important for normal heart development, since excess RA is teratogenic, resulting in cardiac defects in humans and model organisms (Lammer et al., 1985; Mark et al., 2006; Pan and Baker, 2007). The tetratogic effect was found in majority of our test subjects. This could be due to poor judgment on our part as well as the formaldehyde in which the embryos were fixed because in most cases the eye development was not very clear. In other words, we could, as a results of error, classify a normal embryo as posterioriozed and that’s a source of