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Figure 1:
Pristionchus pacificus (A) and Caenorhabditis elegans (B) adult hermaphrodites have similar sizes and shapes. Scale bar 50 µm.
Figure 2:
Life cycle of Pristionchus pacificus. Differential interference contrast images of developmental stages. Development from the two-cell stage to adult takes approximately 72 hrs at 20°C. Each post-embryonic stage is positioned with its left side facing the reader, except the J4, which is facing the right side. Scale bar, 50 µm.
Figure 3:
Unhatched J2. The presence of a shed J1 cuticle (arrowhead) is indicative of the J1 to J2 molt occurring prior to hatching. Scale bar, 10 µm.
Figure 4:
(A) The cuticle of P. pacificus contains longitudinal stippled lines around the circumference of the animal. Scale bar, 10 µm. (B) In an EM cross section, this stippling can be seen as waves around the animal (arrowheads). Scale bar, 1 µm. Image source: Ralf Sommer Lab, Bumbarger13–1301. (C, D) The cuticle of P. pacificus is interrupted by epithelial gland cell pores. In DIC (C), the small gland cell pores (arrow) are occasionally visible both dorsal and ventral of the midline (deirid, arrowhead). Scale bar, 10 µm. In EM cross sections (D), the epithelial gland cell (purple) is surrounded by the hypodermis. Scale bar, 1 µm. Image Source: Ralf Sommer, Bumbarger14–1955.
Figure 5:
Transverse EM section through the P. pacificus head showing body wall muscles (green) lying against body wall. Scale bar, 1 µm.
Figure 6:
Transverse TEM micrograph through junction of excretory glands with canal cell and secretory vesicle being released in gland cell ampulla (arrowhead). Scale bars, 1 µm. Source: Ralf Sommer lab, Bumbarger13_2251.
Figure 7:
(A) Longitudinal EM through stoma of eurystomatous form with dorsal tooth (arrowheads). The dorsal tooth attaches to pharyngeal muscle (green) and contains an opening for vesicles from the dorsal pharyngeal gland (purple) to be released into the stoma. A subventral tooth (arrow) is seen on the opposite side. Scale bar, 1 µm. (B) Transverse EM micrograph through a euryostomatous stoma showing dorsal tooth (arrowhead) with lumen for dorsal pharyngeal gland secretions. A subventral tooth (arrow) is found in the subventral sector of the stoma. Scale bar, 1 µm. (Image source: Ralf Sommer Lab, Bumbarger13–154.) C,D. DIC comparison of eurystomatous (C) and stenostomatous (D) forms. The eurystomatous form contains an obvious dorsal tooth (arrowhead). (Image source: Erik Ragsdale.)
Figure 8:
P. pacificus young adult hermaphrodite gonad. Unlike in C. elegans, the distal arms of the P. pacificus gonad extend back to the ventral side. Scale bar, 10 µm.
