PLANE OF CLEAVAGE -
1. Meridional plane - Cleavage forrow passing through the middle, animal vegital poles axis. eg. Amphioxis, frog and first cleavage of chick.
2. Vertical or longitudinal plane - The vertical cleavage pass through the animal & vegital pole but not through the median axis. The cleavage furrow pass either to the right or left of the axis. eg. III cleavage of chick.
3. Equitorial plane - The cleavage furrow is horizontal / transverse and it pass between the animal & vegital pole. eg. I cleavage of the higher mammals including man.
4. Lattitudinal plane - The previous furrow is transversely or horizontally not on the equator. eg. III cleavage in the egg of amphioxis and frog.