Analysis of the relationship between the variation in intercleavage times and cell diversification during the cleavage stages of the teleost fish Nothobranchius guentheri.

Abstract

A cell lineage study up to the ninth cleavage of the annual teleost fish Nothobranchius guentheri is presented and analysed with respect to a possible relationship between cell diversification and intercleavage times. The cleavage pattern contains both regular aspects (formation of the external yolk syncytial layer) and irregular aspects (formation of the deep cells and the enveloping layer cells). Cells that generate cells which divide again have a similar intercleavage time independent of the cell type of their daughters. Peripheral blastomeres with a shorter intercleavage time, that are situated near the centre of the blastoderm, contribute more to the formation of the deep cell population than those blastomeres with a longer intercleavage time, that lie closer to the margin of the blastoderm. No evidence was found for a relationship between the duration of the cell cycle and the cell type(s) a cell generates, nor for the involvement of mitotic gradients in cell diversification.