QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

Help viewing high resolution images Return to article

Fig. 2. Isolated spherical blastomeres divide differently from cells in the embryo and often bisect a small apical surface. (A) Example of a colour-coded frame from a time-lapse movie that shows the three possible spindle orientations in the embryo, quantified for the 128- to 256-cell division in 10 embryos (n=447 divisions). Par., parallel; Per., perpendicular; Obl., oblique, as defined in the Materials and methods. (B) These three types of spindle orientation occur also in isolated blastomeres at 128-cell stage, as example frames from Movies 1-7 in the supplementary material show; however, the proportion of each type of division differs. (C) Comparison of the proportions of the three division types between the embryo (white bars) and isolated blastomeres, n=151 (black bars). Oblique and perpendicular divisions have significantly different proportions in isolated cells when compared with the embryo (-square goodness of fit, P=0.001). (D) In control embryos, cells with a very small apical surface (less than or equal to one quarter of its sister) will always divide perpendicularly and the apical pigment is not divided. Arrows in D indicate cells with a small apical domain. (E,F) In isolated blastomeres (E) and in embryos that were raised in Ca²⁺/Mg²⁺-free medium (D), such small apical surfaces do become divided. (F) Comparison of frequencies with which the cleavage plane divides a small apical surface. In control embryos: 0% (n=42 divisions in time-lapse movies of 24 embryos). In embryos raised in Ca²⁺/Mg²⁺-free medium, with rounded cells: 32% (n=60 cells with small apical surface were analysed in 12 different embryos).

Return to article