Figure 3.

Stem, progenitor, proliferating, and differentiated cells exhibit specific localization within villi and crypts at Hatch. Immunofluorescence (IF) of enterocyte marker fatty acid binding protein (FABP), proliferating cell nuclear antigen (PCNA), DAPI nuclear staining, and their merge at X100 magnification (A–D), and X400 magnification (E–H), and stem/progenitor cell marker SRY-Box Transcription Factor 9 (Sox9), PCNA, DAPI, and their merge (I–L) at Hatch. FABP expression was localized to all villus cells (E, dashed outlines). Proliferating cells were found along the villus (F, asterisks), overlapping FABP⁺ cells. Sox9 expression was restricted to crypts (I). Arrows indicate Sox9⁺/PCNA⁻ cells, arrowheads indicate Sox9⁺/PCNA⁺ cells, arrow outlines indicate Sox9⁻/PCNA⁺ cells, and arrowhead outlines indicate Sox9⁻/PCNA⁻ cells (I,J).