. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. D Figure 4. Surface change of eggs immediately alter Icrtili/ation (inseminated 40 min alter 1-MeAde treatment). (A) Forty seconds after insemination. A number of panicles are observed in the perivitelline space (perivitelline-space particles). (B) Two minutes after insemination. Note thin processes (fixing processes; arrow) connecting the fertili/ation envelope and tlie egg. Perivitelline-space particles (arrowheads) moved along the fixing processes towards the fertilization envelope. (C) Three minutes after insemination. N
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. D Figure 4. Surface change of eggs immediately alter Icrtili/ation (inseminated 40 min alter 1-MeAde treatment). (A) Forty seconds after insemination. A number of panicles are observed in the perivitelline space (perivitelline-space particles). (B) Two minutes after insemination. Note thin processes (fixing processes; arrow) connecting the fertili/ation envelope and tlie egg. Perivitelline-space particles (arrowheads) moved along the fixing processes towards the fertilization envelope. (C) Three minutes after insemination. Note the prominent cone-like shape at the bases of the fixing processes (white arrowheads). Very few perivitelline-space particles could be seen in the perivitelline space. (D) The 2-cell stage (3 h after insemination). Fixing processes were elongated in the vicinity of the cleavage furrow and were shortened near the boundary between the areas of the blastomeres touching the fertilization envelope. Scale bar: 50 jim. tion of the cytoplasm (Fig. 6B. white arrow), reaching a length of 2 /LUTI. The diameter of these fibers was 5-6 nm, so they can be considered microfilaments. Crossing the microfilament bundle, repeated bands were observed (Fig. 6B, black arrowheads). We could not examine microfilaments in the fixing pro- cesses by transmission electron microscopy, because the fixing processes were not preserved by the quick-freeze and freeze-substitution fixation that effectively preserves micro- filaments. To get information on these microfilaments, we examined the effects of cytochalasin D on the fixing pro- cesses. When the cytochalasin was applied to fertilized eggs, intact fixing processes disappeared within several minutes of treatment, and only fragmented fixing processes were observed in the perivitelline space (Fig. 7A). In em- bryos pulse-treated with the cytochalasin at early cleavage stages, the fixation of blastomeres on the fertilization enve- lope were severely damag
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
