Fig. 2. Salivary glands have several characteristics of apoptosis, and appear to degrade without the assistance of phagocytes. (A-C) TUNEL assay was used to distinguish nuclei that contain fragmented DNA from cytoplasmic fragments and possible phagocytes. (A) Salivary glands possess TUNEL-positive nuclei (arrows) 14 hours apf. (B) TUNEL-positive nuclei (arrows) are surrounded by TUNEL-negative structures that are presumably fragments of salivary gland cytoplasm 15 hours apf, as well as by a small number of unidentified cells (asterisks) that did not contain obvious cell corpses. (C) At 16 hours apf, few TUNEL-positive structures are present in the location where salivary glands reside prior to destruction, and unidentified cells (asterisks) are present, but do not contain obvious dead cell corpses. (D) Transmission electron micrograph of salivary glands 14.5 hours apf, showing the separation of the nucleus (n) from the cytoplasm (c). (E) Membranous structures reminiscent of smooth endoplasmic reticulum are present in some of the balls of cytoplasm (c). Images in A-C are the same magnification. Scale bars: in D, 10 µm; in E, 1 µm.