The Endostyle of Invertebrate Chordates May Have Been the Precursor

Question

The endostyle of invertebrate chordates may have been the precursor to the vertebrate
A)gall bladder.
B)liver.
C)thyroid gland.
D)pancreas.
E)esophagus.

Accepted Answer

The endostyle of invertebrate chordates is a glandular groove in the ventral floor of the pharynx that secretes iodinated proteins involved in iodine metabolism. This glandular system may have given rise to the thyroid gland in vertebrates, which also secretes iodinated proteins, including thyroid hormones. The other options (gall bladder, liver, pancreas, and esophagus) are not directly related to the endostyle.