Fig. 4. The nuclei of Cancer midgut epithelial endocrine cells are located within their enlarged basal region [Cancer magister posterior midgut caecum (PMC) is shown as an example]. (A) Cross-section of the posterior midgut caecum showing the overall distribution of (A1) substance P-like immunoreactivity (pseudocolored red) and (A2) DAPI labeling (pseudocolored blue) in this structure. A3 is a pseudocolored merger of images A1 and B2. All images in this set are brightest pixel projections of 40 optical sections collected at 1.95-µm intervals, with the substance P and DAPI images collected sequentially. A1 and A2 are shown at the same scale, with the scale bar in A2 equal to 200 µm. The scale bar in A3 is also equal to 200 µm. (B) One immunopositive endocrine cell from A shown at higher magnification. When the images of the substance P immunoreactivity (B1) and DAPI label (B2) are merged (B3), the nucleus of the epithelial endocrine cell (arrow in B2 and B3) can clearly be seen to reside in the enlarged basal region. It should be noted that many other nuclei are present in this micrograph. The large elongate nuclei in the lower portion of B2 and B3 are probably those of epithelial cells, whereas the small, round nuclei in the upper portion of the image may be those of hemocytes. As in A, the substance P and DAPI images shown in B were collected sequentially. All images in this set are brightest pixel projections of 28 optical sections collected at 1.05-µm intervals. B1 and B2 are shown at the same scale, with the scale bar in B2 equal to 25 µm. The scale bar in B3 is also equal to 25 µm.