|
A Summary of Events During the First
Three Hours of Embryonic Development
The initial 13 nuclear divisions are syncytial, synchronous, and rapid (18-18 minutes).
Early embryonic development in the fruit fly Drosophila melanogaster is extremely rapid. The first 13 nuclear divisions are completed in just over 3 hours and occur in the absence of cytokinesis, producing an embryo of some 6000 nuclei in a common cytoplasm. During these syncytial divisions, the body axes and segments are established. Three cell (nuclear) types are also formed: yolk nuclei, germ cells, and somatic cells. The dividing nuclei progress through an orchestrated series of migrations to situate in a well-organized monolayer of nuclei at the actin-rich cortex. These events occur on a time-scale of minutes (many of the nuclear cycles are less than 10 minutes in length). In spite of the speed and crowding of the nuclei, the fidelity of these events is high. Research, especially during the past decade, indicates that this is in large part the result of centrosomal and cytoskeletal-based activities that coordinate nuclear division and migration.
Sullivan, W. and Theurkauf, W. (1995). The cytoskeleton and morphogenesis of the early Drosophilia embryo.Current Opinion in Cell Biology 7:18-22.
Yu, K. R., R.J. Duronio, and W. Sullivan. (1998) Cell cycle checkpoints: safe passage through mitosis. In "Frontiers in Biolgy." Oxford University Press
Sisson, J.C., W.F. Rothwell, and W. Sullivan. (1999) Cytokinesis: Lessons from Rappaport and the Drosophila blastoderm embryo.Current Biology International 23:871-876.
Rothwell, W.F. and W. Sullivan. (2000) The centrosome in early Drosophila embryogenesis. Current Topics in Developmental Biology 49:409-447.
Tram, U., B. Riggs, and W. Sullivan. (2001) Cleavage and gastrulation in Drosophila embryos. In Encyclopedia of Life Sciences.
|
