[Mirror symmetrical and "left dominant" organization in the gastrula stage molted parabiotic larva of mountain salamander].

Gastrulae of Triturus alpestris were laterally fused (body axes in equal directions). The parabiotic larvae mostly showed an undivided body with tail, but exhibited two heads. Defects of organogenesis were frequently observed in the gut, and, to some fewer extent, in the heart. The gut mostly develops undivided, the heart in singular or (with transitions) as two organs. The number of organ-inversions and partial inversions was high (table 1). In addition a transindividual organ-symmetry (mirror-image symmetry of the "pair situs") was abundant (table 3, fig. 6) and the gut and the habenular nuclei showed a strong dominance for that phenotype. The organ inversions were more abundant in the right organ or part of the organ. These right-left-differences were statistically significant referring to the inversion tendency of the heart and the habenular nuclei (table 2). This "left-dominance" observed in the organ Anlagen investigated is discussed in regard to results published previously.