Endocrine System, Subphylum Cephalochordata

The cephalochordate brain contains neurosecretory neurons that possibly are related to a structure called Hatschek's pit, located near the brain. Hatschek's pit appears to be related to the neural gland and hence to the vertebrate pituitary gland. Treatment of amphioxus with GnRH or luteinizing hormone (LH) reportedly stimulates the onset of spermatogenesis