Summary
Eels were adapted to black- or white-coloured backgrounds and the pituitary glands were prepared for light and electron microscopy. Immunocytochemical staining was used to study the distribution of the neurohypophysial melanin-concentrating hormone in the neurointermediate lobe. The hormone was located in small, elliptical, electron-opaque neurosecretory granules, measuring approximately 120×90 nm. The neurones terminated on blood vessels in the centre of the neurohypophysis and on the basement membrane separating neural and intermediate lobe tissues. The results of both light and electron immunocytochemistry and of radioimmunoassay are consistent with a higher rate of hormone release from eels adapted to white backgrounds than from those adapted to black backgrounds. In addition to this, when fish that had been adapted to white tanks were transferred to black tanks, there was an accumulation of irMCH in the gland and an increased numerical density of secretory granules at nerve terminals. These results reinforce the proposal that MCH is released during adaptation to a white background, to cause melanin concentration and to inhibit MSH release, and that its release is halted in black-adapted fish.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Baker BI (1979) The evolution of ACTH, MSH and LPH — structure, function and development. In: Barrington EJW (ed) Hormones and evolution. Vol 2. Academic Press, New York London, pp 643–722
Baker BI, Ball JN (1975) Evidence for a dual pituitary control of teleost melanophores. Gen Comp Endocrinol 25:147–152
Baker BI, Ranee TA (1983) Further observations on the distribution and properties of teleost melanin-concentrating hormone. Gen Comp Endocrinol 50:423–431
Baker BI, Bird DJ, Buckingham JC (1986) Effects of chronic administration of melanin-concentrating hormone on corticotrophin, melanotrophin and pigmentation in the trout. Gen Comp Endocrinol 63:62–69
Barber LD, Baker BI, Penny JC, Eberle AN (1987) Melanin-concentrating hormone (MCH) inhibits the release of α-MSH from teleost pituitary glands. Gen Comp Endocrinol 65:79–86
Bendayan M, Stephens H (1984) Double labelling cytochemistry applying the protein A-gold technique. In: Polak JM, Varndell IM (eds) Immunolabelling for electron microscopy. Elsevier, Amsterdam, New York, pp 143–154
Bowley TJ, Ranee TA, Baker BI (1983) Measurement of immunoreactive-melanocyte stimulating hormone in the blood of the rainbow trout kept under various conditions. J Endocrinol 97:267–275
Danscher G (1981) Localisation of gold in biological tissue: A photochemical method for light and electron microscopy. Histochemistry 71:81–88
Danscher G, Norgaard JOR (1983) Light microscopic visualisation of colloidal gold on resin-embedded tissue. J Histochem Cytochem 31:1394–1398
De Mey J (1983) Colloidal gold probes in immunocytochemistry. In: Polak JM, Van Noorden S (eds) Immunocytochemistry: practical applications in pathology and biology. John Wright, Bristol pp 82–112
Geuze HJ, Slot JW, Van Der Ley PA, Scheffer CJ, Griffith J (1981) Use of colloidal gold particles in double labelling immunoelectron microscopy of ultrathin frozen sections. J Cell Biol 98:653–665
Gilham ID, Baker BI (1984) Evidence for the participation of a melanin-concentrating hormone in physiological colour change in the eel. J Endocrinol 102:237–243
Holgate CS, Jackson P, Cowen PN, Bir CC (1983) Immunogoldsilver staining: New method of immunostaining with enhanced sensitivity. J Histochem Cytochem 31(7): 938–944
Huang WM, Gibson SJ, Facer P, Gu J, Polak JM (1983) Improved section adhesion for immunocytochemistry using high molecular weight polymers of L-lysine as a slide coating. Histochemistry 77:275–279
Kawauchi H, Kawazoe I, Tsubokawa M, Kishida M, Baker BI (1983) Characterisation of melanin-concentrating hormone in chum salmon pituitaries. Nature (Lond) 305:321–323
Knowles F, Vollrath L (1965) A functional relationship between neurosecretory fibres and pituicytes in the eel. Nature (Lond) 208:1343
Knowles F, Vollrath L (1966) Neurosecretory innervation of the pituitary of the eels Anguilla and Conger. 1. The structure and ultrastructure of the neurointermediate lobe under normal and experimental conditions. Philos Trans R Soc [Biol] 250:311–327
Leatherland JF, Dodd JM (1969) Activity of the hypothalamoneurohypophysial complex of the European eel (Anguilla anguilla L.) assessed by the use of an in situ staining technique and by autoradiography. Gen Comp Endocrinol 13:45–59
Naito N, Nakai Y, Kawauchi H, Hayashi Y (1985) Immunocytochemical identification of melanin-concentrating hormone in the brain and pituitary of the teleost fishes Oncorhynchus keto and Salmo gairdneri. Cell Tissue Res 242:41–418
Newman JR, Jasani B, Williams ED (1983) A simple post-embedding system for the rapid demonstration of tissue antigens under the electron microscope. Histochemical J 15:543–555
Öztan N (1966) The structure of the hypothalamic neurosecretory cells of Zoares viviparus L. under conditions of constant dark and light during the reproductive cycle. Z Zellforsch 75:66–82
Ranee TA, Baker BI (1979) The teleost melanin-concentrating hormone — a pituitary hormone of hypothalamic origin. Gen Comp Endocrinol 37:64–73
Rodrigues KT, Sumpter JP (1984) Effects of background adaptation on the pituitary and plasma concentrations of some pro-opiomelanocortin related peptides in the rainbow trout (Salmo gairdneri). J Endocrinol 101:277–284
Simionescu N, Simionescu M (1976) Galloylglucoses of low molecular weight as mordant in electron microscopy. J Cell Biol 70:608–633
Slot JW, Geuze H (1981) Sizing of protein A-colloidal gold probes for immunoelectron microscopy. J Cell Biol 90:533–536
Slot JW, Geuze H (1985) A new method of preparing gold probes for multiple labelling cytochemistry. Eur J Cell Biol 38:87–93
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Powell, K.A., Baker, B.I. Structural studies of nerve terminals containing melanin-concentrating hormone in the eel, Anguilla anguilla . Cell Tissue Res. 251, 433–439 (1988). https://doi.org/10.1007/BF00215852
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00215852