Pristionchus pacificus is a nematode model for the developmental genetics of morphological polyphenism, especially at the level of individual cells. Morphological polyphenism in this species includes an evolutionary novelty, moveable teeth, which have enabled predatory feeding in this species and others in its family (Diplogastridae). From transmission electron micrographs of serial thin sections through an adult hermaphrodite of P. pacificus, we three-dimensionally reconstructed all epithelial and myoepithelial cells and syncytia, corresponding to 74 nuclei, of its face, mouth, and pharynx. We found that the epithelia that produce the predatory morphology of P. pacificus are identical to Caenorhabditis elegans in the number of cell classes and nuclei. However, differences in cell form, spatial relationships, and nucleus position correlate with gross morphological differences from C. elegans and outgroups. Moreover, we identified fine-structural features, especially in the anteriormost pharyngeal muscles, that underlie the conspicuous, left-right asymmetry that characterizes the P. pacificus feeding apparatus. Our reconstruction provides an anatomical map for studying the genetics of polyphenism, feeding behavior, and the development of novel form in a satellite model to C. elegans.

This dataset was collected by manually annotating an alignment of digitized, transmission electron microscopy images. These manual annotations resulted in volume-segmented objects, in which segmentation errors were then manually corrected. Additional processing included global operations on each object to improve visualization.

All volume-segmented objects are represented by Wavefront (.obj) files. Wavefront files need to be held in the same directory as their associated .mtl files, which can be imported together with the .obj file into object visualization software. Several software platforms can be used with this file type; for the manuscript associated with this dataset, the authors visualized objects using the open-source platform Blender (blender.org).