In the later larval body, the hydropore opens to the right side of the larva (Fig.
The hydropore is formed on one of the primary interradial plates.
Weakly positive signals were recognized in the hydropore
, the entire or portions of the intestinal epithelium, and the stomach epithelium (Fig.
is located dorsally at the base of the longer arm; it is a small orifice of about 10 [micro]m in diameter.
On the dorsal side, dark pigment was also present in the posterior region, and the hydropore
was strongly marked by dark pigment.
Before or during hatching, the hydropore opens as a shallow invagination on the left side of the plane of bilateral symmetry [ILLUSTRATION FOR FIGURE 2D OMITTED].
By the time the hatching process is near completion, on day 5, all five hydrocoel lobes have formed and the hydropore opens via the ciliated hydroporic canal [ILLUSTRATION FOR FIGURE 3E OMITTED].
In most types, the water vascular passages open to the exterior through a hydropore
or compound mad-reporite, and fluid within the system is used hydraulically to extend agile appendages, the tube feet.