Figure 2.

Cartoons of Caenorhabditis elegans (A) and Steinernema carpocapsae (B) gonads and lateral left view (anterior to left) micrograph of posterior S. carpocapsae gonad arm (C): differential interference contrast (DIC) alone (top); DIC color overlay (bottom). Unlike C. elegans, which undergoes stereotypical development to a ‘U-shaped’ gonad, the most common S. carpocapsae gonad shape does not include extensive migration along the ventral wall. As shown in the stitched DIC micrograph (C) (top) and with transparent color overlay (bottom), the gonad extends from the central region of the animal near the vulva (position indicated with straight arrow) and immediately extends to the dorsal side where it extends away from the mid-body. It eventually makes a u-turn (curved arrow) and then extends along the dorsal wall back to the mid-body where it then migrates back to the ventral wall. The posterior gonad arm typically wraps around the left side of the intestine, whereas the anterior arm typically wraps around the right side of the intestine. The proximal end of the gonad, including the uterus and spermathecal-uterine complex, is colored red. The distal end of the gonad following the turn includes the ovary and is colored blue. Scale bar, 50 µm.