Hatschek’s pit
Quick Summary
Hatschek's pit is a structure found in the subphylum Cephalochordata, which includes animals like the amphioxus (lancelet). This pit is located near the brain and appears to be connected to the neural gland, suggesting a relationship to the vertebrate pituitary gland.1
Research indicates that extracts from Hatschek's pit can stimulate the testes of toads. Additionally, the cephalochordate endostyle, similar to that in ascidians, can synthesize thyroid hormones. These findings suggest that the fundamental organization of the vertebrate endocrine system may have originated in the simpler organs of these invertebrate chordates.1
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