HypFIG 6: Division of seam blast cells in L1.
Epifluorescent image of transgenic animals expressing the ajm-1::GFP reporter in the hypodermis. (Strain source: H. Yu and P.W. Sternberg.)
A. Left lateral view. Approximately 5 hours after hatching, the seam cells round up and divide. H0 does not divide at any stage. In this animal H1, H2, V6 and T have not yet divided. Anterior daughters (stars) of V2-V5 have started to insert themselves between the P cells, separating them from one another. (P) Six left-side cells of the P1-P12 pairs. (a) Anus; (inset) V5 is generally the first seam cell to divide.
B. Left lateral oblique view. Approximately 7 hours after hatching. The cytoplasmic processes of the anterior daughters of V2-V6 open up the adherens junctions between the neighboring P cells in each row, isolating each P-cell pair. Some of these cells have either already fused with hyp 7 (arrow) or are in the process of fusing (stars). (Arrowheads) Dissolving adherens junctions of these cells. H1, H2, V1 and T have just divided. Six left-side cells of the P1-P12 pairs are marked with P. (vm) Ventral midline; (a) anus.
C. Left lateral view. Approximately 8 hours after hatching and 3 hours after they are generated, anterior descendants of seam cells fuse to hyp 7, with their nuclei remaining close to the seam cells on each side (not shown). (a) Anus.
D. Left lateral view. Each left and right pair of P cells is detached from its anterior-posterior neighbors by fusion of the anterior seam descendants with hyp 7, producing six pairs of isolated P cells. P1/2 have started to rotate to align along the midline. (Stars) Anterior daughters of V6 and T are in the process of fusion with hyp 7. (a) Anus.
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