Caudalization by retinoic acid is correlated with inhibition of cell population growth and expansion of chick blastoderms cultured in vitro.
Full primitive streak stage chick embryos, cultured in vitro for 20 h in the presence of 10(-9) to 10(-7) moles of retinoic acid (retinol, all-trans), exhibit increasing extent of malformations. RA causes caudalization, suppression of telencephalon, formation of open and enlarged neural tube in the regions of midbrain, hindbrain and spinal cord, failure of fusion of heart tubes, and gives rise to winged or diffused, and even supernumerary somites. Extreme abnormalities include failure to form the head fold and foregut. Abnormal embryos were graded according to Rao and Chauhan (Teratology 4: 191-198, 1971), and we find that the larger the severity of malformation, the smaller the size of total cell population and blastoderm area. Concomitant to caudalization, retinoic acid suppresses the cell population growth.
Modak
S P
SP
Department of Zoology, University of Poona, Pune, India.
Ghatpande
S K
SK
Rane
R K
RK
Mulherkar
L
L
D000014:Abnormalities, Drug-Induced; D000818:Animals; D001756:Blastoderm / Q000187:drug effects* / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000196:embryology; D002455:Cell Division / Q000187:drug effects*; D002642:Chick Embryo; D046508:Culture Techniques; D006321:Heart / Q000187:drug effects / Q000196:embryology; D009024:Morphogenesis / Q000187:drug effects; D009436:Neural Tube Defects / Q000139:chemically induced; D013687:Telencephalon / Q000187:drug effects / Q000196:embryology; D014212:Tretinoin / Q000494:pharmacology / Q000633:toxicity*
D014212:Tretinoin