Fig. 5.

Dox treatment rapidly induces apoptosis centering on the putative stem cell zone. A: apoptotic cells were scored via H&E staining of jejunal sections collected at 0, 6, 24, 48, 72, 96, 120, and 168 h after Dox treatment (n = 5–6) and expressed as the number of apoptotic cells per crypt. *Statistical significance compared with zero-time controls (P < 0.05). B: the location of apoptotic bodies within particular cell positions along the crypt was recorded at the 6-h time point. Data are presented as the percent of instances a particular cell position contained an apoptotic cell. The stem/progenitor cell zone is indicated by the shaded boxes. Using the nomenclature of Scoville et al. (37), the gray box indicates the area in which crypt base columnar cells (CBCs) reside and the yellow box indicates the area containing the +4 cells. Note that the green box represents potential overlap of these 2 areas. Inset: H&E micrograph of representative crypts containing apoptotic cells (arrows).