Preferable orientation of the first cleavage furrows of eggs and cranio-caudal axes of neurulae according to the cardinal points in spawn layings of moor frog

摘要

The first cleavage furrows in natural spawn layings of moor frog collected in the forest stand in Moscow district are preferably oriented along the North-South direction. After intented cardinal alteration of initial orientation of laying the cleaving eggs change the attitude restoring the initial distribution of the frequences of furrows orientation. Orientations of cranio-caudal axes of neurulae to the North-South direction are more frequent than according to others directions. Meanwhile, the distributions of the frequences of neurulae cranio-caudal axes are not identical to the same distributions of the first furrow in corresponding layings.