title: A light- and electron-microscopic study of the pineal complex of the ammocoete larva of the southern lamprey Geotria australis.
abstract: The pineal complex of larval Geotria australis lampreys has been examined by light- and electron-microscopy. The complex consists of a pineal organ and a smaller parapineal organ, the former being situated dorsal to the latter. It is concluded that the pineal organ is a functioning photoreceptor, with neural and endocrine output. The parapineal appears to be a more basic neuroendocrine organ without photosensory capability. Day-night comparisons of the pineal complex show no obvious differences in ultrastructure; this could be related to the chronobiological role of the complex as a constant monitor of ambient light levels, rather than a mere visual receptor that changes its sensitivity at night.
authors.affiliation: University of the West Indies, Kingston St. Andrew, Jamaica.
authors.forename: V B
authors.initials: VB
authors.lastname: Meyer-Rochow
authors.forename: D
authors.initials: D
authors.lastname: Stewart
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D004027:Diencephalon / Q000254:growth & development / Q000648:ultrastructure*; D007798:Lampreys / Q000033:anatomy & histology* / Q000254:growth & development; D007814:Larva; D008854:Microscopy, Electron; D009490:Neurosecretory Systems / Q000254:growth & development / Q000648:ultrastructure*; D010870:Pineal Gland / Q000254:growth & development / Q000648:ultrastructure*