Fig. 2
From: Stem cells in Nanomia bijuga (Siphonophora), a colonial animal with localized growth zones
Co-localized vasa-1, pl10, piwi, nanos-1, and nanos-2 expression and histology indicate presence of i-cells in the siphosomal growth zone. a Anterior part of the siphosome, stained blue for vasa-1 transcript. Lateral view. Anterior is up, ventral to the left. b Close-up of growth zone region boxed region in a. vasa-1 expression within the horn of the growth zone (h, filled arrowhead). c–f Anterior part of the siphosome, stained blue for pl-10 (c), piwi (d), nanos-1 (e), and nanos-2 transcript (f). g Semi-thin longitudinal section of the tip of the siphosomal growth zone stained with toluidine blue. h Siphosomal horn, close-up of box in g. i Transmission electron micrograph of the ectoderm of the siphosomal horn. Cells with i-cell morphology reside in between epithelial muscle cells of the ectoderm. j Tip of youngest gastrozooid, close-up of box in g. b bract, ec epithelial cell, ect ectoderm, end endoderm, g gastrozooid, gc gastric cavity, h horn of the growth zone, ic interstitial cell, m mesoglea, n nucleus, nst nectosomal stem, p palpon, sst siphosomal stem