Fig. 6

Details of the fate map and cleavage pattern of the animal, vegetal, and internalized blastomeres of M. membranacea. a Representation of the B quadrant at the 48-cell stage (9.0 hpa) in frontal view (left). Frontal view of the embryo at the mid gastrula stage (16.0 hpa) with left, right, and top regions “opened” for visualization (right); the shades of blue correspond to the blastomeres of the 48-cell stage (left). White lines illustrate cell borders of further progeny from the blastomeres indicated. Color-coding of the remaining blastomeres indicate their quadrant of origin. b Cleavage patterns of the vegetal ectoderm viewed from the vegetal pole at the 28-cell stage (6.7 hpa). The vegetal plate progenitors consist of 12 blastomeres lining at the 32-cell stage (7.5 hpa). These cells divide once, forming 12 derivatives, lining the forming blastopore at the 90-cell stage (9.7 hpa). At the subsequent divisions (15.2 hpa), progeny from the cells at the vertices (2a^L2, 2b^R2, 2d^R2, and 2c^L2) disconnect from the blastopore lip. At this stage, only eight cells are lining the blastopore. The cells 3c¹ and 3c² do not divide. c Cleavage patterns of the four large vegetal blastomeres internalized during gastrulation, frontal view. Quadrant color coding: A (green), B (blue), C (purple), D (red)