Fig. 4

The intestine of Styela plicata presents PIWI + cells and pHH3 + cells. a–c Phosphohistone (pHH3) immunofluorescence shows antibody reaction in the region of the intestinal epithelia in Styela plicata. All cell nuclei were stained with DAPI (blue). a Wide view of the submucosa region, showing hemoblast aggregations (delineated by dotted lines), glandular structures are highlighted with asterisks. Labeled cells are pseudocolored red. b Wide view of the intestine subepithelial region below the serosa. Glandular structures are highlighted with asterisks. c Detail of labeled cells with pHH3 antibody in the submucosa. d–f Immunofluorescence showing antibody reaction with PIWI in the subepithelial region of S. plicata intestine. All cell nuclei were stained with the nucleus marker DAPI (blue) (d) Detail of the submucosa, labeled cells are pseudocolored green. e Detail of the subepithelial region. f Intestinal villi showing PIWI + cells at the subepithelial region. g Cell counts of pHH3 + cells in different regions of the intestine and the epidermis as an external control tissue (left) and PIWI (right) immunofluorescence in the intestine. Epidermis tissue was used for the control group. h Distribution of the serosa, submucosa, and mucosa cell types in a transverse section of the S. plicata gut showing the range of distribution of pHH3 (red) and PIWI (green) positive cells. (*p < 0.05). (se) serosa, (sm) submucosa, (m) mitochondria, (n) nucleolus. Scale bars = 100 µm in a, b; 20 µm in c–f