Ballanoglossus has no definite endoskeleton of bone or cartilage . The four stiff structures are present:
Buccal diverticulum-A short stiff, thick-walled,holllow projection extend forwards through the proboscis stalk into the proboscis coelom.Its wall is composed of a single layer of tall,slender,vacuolated endodermal cell.
Proboscis skeleton-The proboscis or nuchal skeleton is a y-shaped chitinous structures formed by the thickening of the basement membrane.It consists of a broad,flat,roughly rectangular median plate priduced ventrally into a keel and posteriorly into two diverging horns
Branchial skeleton-It is formed by the thickening of the basement membrane.It consists of numerous M-shaped chitinous skeletal rods that lie in the wall of the pharynx and support the U-shaped gills that perforate.
Pygochord-In the post-hepatic region of the trunk,mid-ventrally between the intestine and body wall,develops a rod-like thickening called pygochord.
Buccal diverticulum-A short stiff, thick-walled,holllow projection extend forwards through the proboscis stalk into the proboscis coelom.Its wall is composed of a single layer of tall,slender,vacuolated endodermal cell.
Proboscis skeleton-The proboscis or nuchal skeleton is a y-shaped chitinous structures formed by the thickening of the basement membrane.It consists of a broad,flat,roughly rectangular median plate priduced ventrally into a keel and posteriorly into two diverging horns
Branchial skeleton-It is formed by the thickening of the basement membrane.It consists of numerous M-shaped chitinous skeletal rods that lie in the wall of the pharynx and support the U-shaped gills that perforate.
Pygochord-In the post-hepatic region of the trunk,mid-ventrally between the intestine and body wall,develops a rod-like thickening called pygochord.
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