(a) Cartoon showing EdU pulse-chase strategy to examine the differentiation of stem cells into tsp-2+ cells. (b) Quantification of the number of EdU+tsp-2+or EdU+cathepsin B+ cells following a single pulse of EdU given to parasites in vivo. Percentages of EdU+ tsp-2+/total tsp-2+ cells were D1 0.22% (2/917), D3 41% (323/787), D5 52% (299/575), 13% (57/437), D9 8.1% (49/603), D11 1.4% (8/567). Percentages of EdU+ Cathepsin B/ total Cathepsin B+ cells were D1 0% (0/1570), D3 2.4% (26/1057), D5 2.9% (61/2044), D7 4.2% (58/1359), D9 4.3% (106/2469), D11 3.9% (64/1646). Data were collected from > 5 male parasites recovered from two separate mice, except for cathepsin B labeling at D11 where parasites were recovered from a single mouse. (c, d) Fluorescence in situ hybridization showing the EdU labeling of tsp-2+ or cathepsin B+ cells at various time points following an EdU pulse. Scale bars, 15 µm. (e) Potential models for tegumental cell differentiation.