Organismal polarity of V. rousseletii. (a)1 Closeup view of somatic cells at the anterior pole (see frame in Figure 1c). (a)2-(a)4 Individual somatic cells from the anterior pole at high magnification. (b)1, Closeup view of somatic cells at the posterior pole (see frame in Figure 1c). (b)2-(b)4 Individual somatic cells from the posterior pole at high magnification. (c) The swimming direction of V. rousseletii along its posterior-anterior axis is indicated by a white arrow. The progeny are within the posterior hemisphere. The polar diameter of the spheroid is always greater than the equatorial diameter. The frames indicate the areas shown in (a)1 and (b)1. (d) The diameter of the eyespots was plotted against the linear distances between the respective somatic cells and the anterior pole (n = 24). (e) Size of the eyespot surface area at the anterior and posterior poles (n = 15). (f) Size of the protoplast surface area at the anterior and posterior poles (n = 60). (g) Distance between protoplasts at the anterior and posterior poles (n = 250). (e)-(g) Error bars indicate the standard deviation of the y-value. (d)-(g) The sizes and distances were calculated from the photomicrographs.