Pheromonal stimulation of spawning release of gametes by gonadotropin releasing hormone in the chiton, Mopalia sp.

The chiton Mopalia sp., a mollusc, was exposed to various dilutions of gonadotropin releasing hormone (GnRH) in sea water to determine whether this peptide is capable of acting as a pheromone that could stimulate release of ripe gametes (spawning). Two of the peptides, lamprey GnRH-1 and tunicate GnRH-2, had this action at a higher concentration (1.

The distribution of lamprey GnRH-III in brains of adult sea lampreys (Petromyzon marinus).

In the sea lamprey, Petromyzon marinus, two forms of GnRH, lamprey GnRH-I and -III, have been demonstrated to be neurohormones regulating the pituitary-gonadal axis. The objective of the present study was to determine the distribution of lamprey GnRH-III in the brains of adult sea lampreys and to compare it to the distribution of lamprey GnRH-I. For this purpose, two kinds of immunostaining were employed: one was a single immunostaining by one of two GnRH antibodies using two successive sections; the other was double immunostaining of a single section.

A brain-Hatschek's pit connection in amphioxus.

In the adult lancelet, Branchiostoma belcheri, there is a lobe of the right ventral margin of the brain that extends around the right side of the notochord and makes contact with Hatschek's pit, which also is to the right of the midline. This structural system resembles the hypothalamo-adenohypophyseal system of vertebrates and appears to make possible seasonal nervous regulation of the release of gonadotropin.