Fourier analysis of the nuclear and cytoplasmic shapes of living two-cell murine embryos

Abstract

Living two-cell mouse embryos were flushed out from the oviduct 17, 24 and 36 hours after fertilization in order to obtain cells in the G1S, early G2 and late G2 phases of the second cell cycle. The nuclei of the living cells were stained with Hoechst 33342. The coordinates of the contour shapes of the entire cells (cellular contours) were registered by contour image processing with a TV camera coupled with a computer; the contours of the nuclei were computed by means of a digitizer coupled with the computer. Fourier analysis of the cellular and nuclear contours revealed systematic modifications in the folding of the cells and nuclei in the course of the murine second cell cycle. The progression of cells through the second cell cycle was correlated with an increasing diversification of cellular and nuclear shape, with the diversification being much more pronounced in the nuclear shapes.