Teleosts are unique among vertebrates regarding neuro- anatomical control of the adenohypophysis. In tetrapods, secretion of anterior pituitary hormones is regulated by the hypothalamus through neurohormones transported to the target cells via the pituitary portal system. Teleosts, however, lack a pituitary portal system, and the adenohypophysis is directly innervated. It is still unclear if there are corresponding differences regarding specificity of the transfer of information. Another interesting difference is the regionalized distribution of different cell types in teleosts, whereas the cell types are randomly distributed within the anterior pituitary in mammals. Furthermore, teleosts have separate cells secreting the two gonadotropins, FSH and LH, in contrast to mammals that only have one gonadotrope cell type producing both hormones. Teleosts are therefore powerful models for investigating the differential regulation of the two gonadotropins. In mammals, the anterior pituitary cells differ regarding both their secretory pattern and electrophysiological properties. Similar ion channels are expressed in all cell types, and the different cell properties are due to differential expression of each channel type. In teleosts, electrophysiological properties of pituitary cells have previously only been reported for two species. We have recently studied the electrophysiological properties of pituitary cells in cod, with special focus on the gonadotropes, and basic electrophysiological properties of a subpopulation of large pituitary cells (presumed gonadotropes) in primary cultures from maturing Atlantic cod will be presented. We are currently setting up single-cell PCR in order to identify the pituitary cells following electrophysiological recordings.