Interkinetic nuclear movements promote apical expansion in pseudostratified epithelia at the expense of apicobasal elongation
Fig 1
Growth of caudal neuroepithelium of the chicken embryo from 2 to 4 days of development.
A. Diagram of a chicken embryo at 48h of incubation (stage HH13-, 18 somites). B, transversal cryosections at the level of the forelimb at 48h, 72 and 96h of incubation. C-D, Confocal images of the intermediate region of the neuroepithelium at the level of the forelimb at 48, 72 and 96h of incubation, nuclei are stained with DAPI (grey) and actin with Phalloidin (green). Magenta line, apical domain; cyan line, basal domain. Note that the basal region progressively becomes devoid of nuclei. E, net dorsoventral length of the neural tube. F, net apicobasal length of the neural tube. G, number of pseudolayers of nuclei along the apicobasal axis. H, distribution of DAPI intensity along the apicobasal axis, normalized to the peak intensity in each dataset and to the apicobasal size so that the various stages can be compared. I, ratio of apicobasal and dorsoventral length of nuclei. J, straightness of apical domain (net distance between dorsal-most and ventral-most points of the apical surface divided by the actual length of the apical surface between these two points). K, positions of mitotic cells (either phospho-histone H3-positive cells or cells with condensed chromosomes from DAPI staining), at scale with the actual apicobasal size of the neural tube. L, positions of mitoses, raw data. Descriptive data collected from 20 embryos. Dots represent mean values. Error bars show the standard deviation. Box and whiskers plot: the box extends from the 25th to the 75th percentile; the whiskers show the extent of the whole dataset. The median is plotted as a line inside the box. AB, apicobasal; DV, dorsoventral; HH, Hamburger-Hamilton stages of chicken development; ss, somites.