Spatial and temporal patterns of cell division during early Xenopus embryogenesis

We describe the spatial and temporal patterns of cell division in the early Xenopus embryo, concentrating on the period between the midblastula transi tion and the early tailbud stage. Mitotic cells were identified using an an tibody recognising phosphorylated histone H3. At least four observations ar e of interest. First, axial mesodermal cells, including prospective notocho rd, stop dividing after involution and may not divide thereafter. Second, c ell division is more pronounced in the neural plate than in nonneural ectod erm, and the pattern of cell division becomes further refined as neurogenes is proceeds. Third, cells in the cement gland cease proliferation completel y as they begin to accumulate pigment. Finally, the precursors of periphera l sensory organs such as the ear and olfactory placode undergo active cell proliferation when they arise from the sensorial layer of the ectoderm. The se observations and others should provide a platform to study the relations hip between the regulation of developmental processes and the cell cycle du ring Xenopus embryogenesis. (C) 2001 Academic Press.