Cell division in a live zebrafish embryo

Time-lapse confocal microscopy of asymmetric (upper) and symmetric (lower) cell division in the brain of a live zebrafish embryo. The upper image sequence shows a single neural progenitor (a cell which can divide and differentiate into a limited number of neural cell types) dividing to produce two daughter cells. One is a neurone (white; upper cell) and the other a progenitor cell (lower cell) which itself divides at the end of the time lapse (right most three images in sequence). Cell nuclei (purple) and cell membranes (green) are visible. This asymmetric mode of cell division allows simultaneous production of both neurones and neural progenitors which are essential for controlling brain growth and differentiation. The lower image sequence shows a single neural progenitor (a cell which can divide and differentiate into a limited number of neural cell types) dividing to produce two similar daughter cells. Both are progenitor cells which then go on to each divide themselves at the end of the time lapse (right most two images in sequence). This symmetric mode of cell division is generally associated with tissue expansion and overgrowth and occurs with higher frequency during the early stages of brain development. Zebrafish embryos are transparent which makes visualising this process ideal. Time lapse lasts approximately 9 hours and width of image is approximately 270 micrometres.