IMMUNOCYTOCHEMICAL STUDIES OF LUTEINIZING-HORMONE-RELEASING HORMONE IN BRAINS OF AGNATHAN FISHES .2. PATTERNS OF IMMUNOREACTIVITY IN LARVAL AND MATURING WESTERN BROOK LAMPREY (LAMPETRA-RICHARDSONI)

An immunocytochemical unlabeled antibody enzyme technique has been applied to localize mammalian-like immunoreactive luteinizing hormone-releasing hormone (ir-LH-RH) in central nervous tissues of Western brook lamprey (Lampetra richardsoni). In larval animals faint specific immunocytochemical staining was found over perikarya in the posterior preoptic nucleus (PON), in fiber tracts passing ventro-posteriorly into the infundibulum, and in nerve endings in the neurohypophysis (NH). In brains of nonreproductive adults, faint staining of cell bodies was observed throughout the PON; staining of NH was intense. In reproductive adults, heavy staining was noted in PON perikarya, in beaded axons containing Herring body-like dilatations, and in NH. Perikarya with ir-LH-RH were distinct from those, presumably vasotocinergic ones, which stained with aldehyde fuchsin; specific immunocytochemical staining was absent in other brain regions and in control preparations. A change in number of cells stained, and in quality of staining was coincident with metamorphosis and sexual maturation; mechanisms by which ir-LH-RH might be transported from the preoptico-neurohypophysial system to the pars distalis to exert any physiological actions have not been established. © 1979.