Microtubules in hindgut cells of late embryos of stage S18 A overlay of epifluorescence and DIC images obtained on paraffin section showing microtubules in green (AlexaFluor 488). Image depicts longitudinal section of the embryo. Arrows point to distinct fluorescent labelling of microtubules in epidermis of the limb buds B overlay of epifluorescence and DIC images obtained on paraffin section showing microtubules in green (AlexaFluor 488) and cell nuclei in blue (DAPI). Image depicts area denoted by frame B in image A. Arrowheads point to diffuse fluorescent labelling in the hindgut C electron micrograph of equivalent area as denoted by frame C in image B. Arrow points to an individual microtubule in the apical cytosol D overlay of epifluorescence and DIC images obtained on paraffin section showing microtubules in green (AlexaFluor 488) and cell nuclei in blue (DAPI). Image depicts cross-section of the rectum near the anal opening. Arrowheads point to apico-basal bundles of microtubules in the rectum. An arrow points to distinct dilator muscles surrounding the rectum. Abbreviations: AN – anal opening; CUT – cuticle; DG – digestive glands; HG – hindgut; RE – rectum.