Fig. 1

CS extrusion is achieved by apical extrusion of multiple renal epithelial cells.

(A) Lateral views of a stage series analysis of CS extrusion in a single live Tg(cdh17:egfp) embryo (top panels) and embryos fixed at the stages shown and stained for cdh17(purple)/stc1(red). (B) Image of a sagittal section through the pronephros of a Tg(cdh17:egfp) embryo co-labelled with Phalloidin (F-actin, red) and DAPI (nuclear stain, blue) at the site of the extruding CS at 38 hpf. (C) Histogram shows the frequency of the four stages of CS extrusion at 24 hpf, 32 hpf, 40 hpf and 50 hpf. (D) Panels show transverse sections through the CS gland of Tg(cdh17:egfp) embryos at the stages indicated. Green fluorescence is from the endogenous GFP, Cdh1 is labelled red and nuclei are labelled blue (DAPI). Dotted box in the 50 hpf panel indicates weak/absent Cdh1 staining at the interface between the ventral side of the CS gland and the dorsal side of the tubule. (E) Panels show lateral views of an extruding CS gland in embryos at the indicated stages labelled with epcam. Abbreviations: PT, Proximal tubule; DE, Distal early tubule segment; CS, Corpuscles of Stannius; DL, Distal Late tubule segment; hpf, hours post fertilisation; Pr, Pronephros.