Figure 10

Developing pillar-type trabecula in the thin distal part of the genital operculum after the fourth embryonic molt (stage 21). Limulus polyphemus. TEM. Hypodermal cells (C) from the opposed walls of the appendage extend processes (Pr) into the lumen (L) where the ends of the cell processes have not yet formed a connection. The lumen contains fine particulate material that is probably hemocyanin [30, 31]. Cu, cuticle; ER, endoplasmic reticulum. Scale, 2 μm.