Previous works have established that RA functions in the patterning of the anterior-posterior positional identities of central nervous system (Holland and Holland, 1996, Escriva et al., 2002, Schubert, 2004, 2005, 2006 and Koop et al., 2010). It can be depicted from the results that the p-test indicates a significant difference between the experimental and control subjects. This means that the retinoic acid, which was added to the experimental group only , have adversely affected the experimental group relative to their counterpart in the control set up. Addition of excess RA to the gastrula stage was demonstrated in amphioxus studies to cause the posteriorization of the central nervous system (Holland and Holland, 1996, Escriva et al, 2002,
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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