Cell and Tissue Research

, Volume 216, Issue 1, pp 113–130 | Cite as

Pineal complex of the clawed toad, Xenopus laevis Daud.: Structure and function

  • H. -W. Korf
  • R. Liesner
  • H. Meissl
  • A. Kirk


The morphological and physiological properties of the pineal complex of Xenopus laevis were investigated in larval, juvenile and adult animals.

In a representative majority of adult X. laevis, the frontal organ does not display signs of degeneration. Fully differentiated frontal organs contain photoreceptors typical of the pineal complex of lower vertebrates. By means of the acetylcholinesterase (AChE)-reaction approximately 30 neurons of two different types were demonstrated in the frontal organ. The frontal-organ nerve is composed of approximately 10 myelinated and 40 unmyelinated nerve fibers. The neuropil areas of the frontal organ are generally similar to the corresponding structures of the intracranial epiphysis.

The neuronal apparatus of the epiphysis cerebri of X. laevis consists of (i) photoreceptor cells, (ii) ∼100 AChE-positive neurons, (iii) complex neuropil areas, and (iv) a pineal tract formed by ∼10 myelinated and ∼100 unmyelinated nerve fibers. Some of them exhibit granular inclusions indicating that pinealopetal elements may enter the pineal complex of X. laevis via this pathway. The topography of the pineal tract of X. laevis differs considerably from that in ranid species. The most conspicuous element of the plexiform zones is the ribbon synapse. The basal processes of the photoreceptor cells may be presynaptic elements of simple, tangential, dyad or triad synaptic contacts. Conventional synapses were observed only occasionally.

Electrophysiological recordings revealed that the pineal complex of Xenopus laevis is directly sensitive to light. In response to light stimuli, two types of responses, achromatic and chromatic, were recorded from the nerve of the frontal organ. In contrast, the epiphysis exhibited only achromatic units. The opposed color mechanism of the chromatic response showed a maximum sensitivity at approximately 360 nm for the inhibitory and at 520 nm for the excitatory event. The action spectrum of the achromatic response of the epiphysis and the frontal organ peaked between 500 and 520 nm and showed no Purkinje-shift during dark adaptation. The functional significance of these phenomena is discussed.

Key words

Pineal complex AChE-positive neurons Plexiform areas Photosensory function Xenopus laevis 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bagnara JT (1964) Independent actions of pineal and hypophysis in the regulation of chromatophores of anuran larvae. Gen Comp Endocrinol 4:299–303Google Scholar
  2. Bagnara JT (1965) Pineal regulation of body blanching in amphibian larvae. Progr Brain Res 10:489–506Google Scholar
  3. Dayrhuber H (1972) Über die Synapsenformen und das Vorkommen von Acetylcholinesterase in der Epiphyse von Bombina variegata L (Anura). Z Zellforsch 126:278–296Google Scholar
  4. Dartnall HJA (1953) The interpretation of spectral sensitivity curves. Br med Bull 9:24–30Google Scholar
  5. Dartnall HJA (1956) Further observations on the visual pigments of the clawed toad, Xenopus laevis. J Physiol 134:327–338Google Scholar
  6. Denton EJ, Pirenne MH (1954) The visual sensitivity of the toad Xenopus laevis. J Physiol 125:181–207Google Scholar
  7. Biederen JHB (1975) A possible functional relationship between the subcommissural organ and the pineal complex and the lateral eyes in Rana esculenta and Rana temporaria. Cell Tissue Res 158:37–60Google Scholar
  8. Dodt E (1963) Reversible Umsteuerung lichtempfindlicher Systeme bei Pflanzen und Tieren. Experientia 19:53–56Google Scholar
  9. Dodt E, Heerd E (1962) Mode of action of pineal nerve fibers in frogs. J Neurophysiol 25:405–429Google Scholar
  10. Dodt E, Jacobson M (1963) Photosensitivity of a localized region of the frog's diencephalon. J Neurophysiol 26:752–758Google Scholar
  11. Dodt E, Morita Y (1964) Purkinje-Verschiebung, absolute Schwelle und adaptives Verhalten einzelner Elemente der intracraniellen Anurenepiphyse. Vision Res 4:413–421Google Scholar
  12. Dodt E, Ueck M, Oksche A (1971) Relation of structure and function: The pineal organ of lower vertebrates. In: Kruta V (ed) J Purkinjě Centenary Symposium Prag 1969. Brno University JE PurkinjěGoogle Scholar
  13. Donley CS, Meissl H (1979) Characteristics of slow potentials from the frog epiphysis (Rana esculenta); possible mass photoreceptor potentials. Vision Res 19:1343–1349Google Scholar
  14. Eakin RM (1961) Photoreceptors in the amphibian frontal organ. Proc Natl Acad Sci (Wash) 47:1084–1088Google Scholar
  15. Eldred WD, Nolte J (1979) Pineal photoreceptors: evidence for a vertebrate visual pigment with two physiological active states. Vision Res 18:29–32Google Scholar
  16. Eldred WD, Finger TE, Nolte J (1980) Central projections from the frontal organ of Rana pipiens, as demonstrated by the anterograde transport of horseradish peroxidase. Cell Tissue Res 211:215–222Google Scholar
  17. Flight WFG (1973) Observations on the pineal ultrastructure of the urodele, Diemictylus viridescens viridescens. Proc Kon Ned Akad Wet Ser C 76Google Scholar
  18. Haffner K von (1950) Über die progressive und regressive Entwicklung der Pinealblase (Parietalorgan) des Krallenfrosches (Xenopus laevis Daud). Verh Zool Gesell, pp 93–100Google Scholar
  19. Hamasaki DI (1970) Interaction of excitation and inhibition in the stirnorgan of the frog. Vision Res 10:307–316Google Scholar
  20. Hamasaki DI, Esserman L (1976) Neural activity of the frog's frontal organ during steady illumination. J comp Physiol 109:279–285Google Scholar
  21. Hamasaki DI, Eder DJ (1977) Adaptive radiation of the pineal system. In: Crescitelli F (ed) Handbook of Sensory Physiology. Vol VII/5 The visual system in vertebrates. Springer, Berlin Heidelberg NewYork, pp 497–548Google Scholar
  22. Hartwig HG, Baumann Ch (1974) Evidence for photosensitive pigments in the pineal complex of the frog. Vision Res 14:597–598Google Scholar
  23. Hogben L, Slome D (1931) The pigmentary effector system. VI. The dual character of endocrine coordination in amphibian color change. Proc Roy Soc B 108:10–53Google Scholar
  24. Karnovsky MJ, Roots L (1964) A “direct coloring” thiocholine method for cholinesterase. J Histochem Cytochem 12:219–221Google Scholar
  25. Korf HW (1976) Histological, histochemical and electron microscopical studies on the nervous apparatus of the pineal organ in the tiger salamander, Ambystoma tigrinum. Cell Tissue Res 174:475–497Google Scholar
  26. Kreht H (1940) Die markhaltigen Fasersysteme im Gehirn der Anuren und Urodelen und ihre Myelogenie; zugleich ein kritischer Beitrag zu den Flechsigschen myelogenetischen Grundgesetzen.II. Kleinhirn, Mittelhirn, Zwischenhirn und Endhirn. Z mikr anat Forsch 48:191–286Google Scholar
  27. Meissl H, Donley CS (1980) Change of threshold after light-adaptation of the chromatic response of the frog's pineal organ (stirnorgan). Vision Res 20:379–383Google Scholar
  28. Morita Y, Dodt E (1965) Nervous activity of the frog's epiphysis cerebri in relation to illumination. Experientia 21:221–222Google Scholar
  29. Munz FW, McFarland WN (1977) Evolutionary adaptations of fishes to the photic environment. In: Crescitelli F (ed) Handbook of Sensory Physiology. Vol VII/5 The visual system in vertebrates. Spinger, Berlin Heidelberg New York, pp 193–274Google Scholar
  30. Nieuwkoop PD, Faber J (1956) Normal table of Xenopus laevis Daudin. North Holland Publ Comp, AmsterdamGoogle Scholar
  31. Oksche A (1955) Untersuchungen über die Nervenzellen und Nervenverbindungen des Stirnorgans, der Epiphyse und des Subkommissuralorgans bei anuren Amphibien. Morph Jb 95:393–425Google Scholar
  32. Oksche A (1971) Sensory and glandular elements of the pineal organ. In: Wolstenholme GEW, Knight J (eds) The pineal gland. A Ciba Foundation Symposium. Churchill-Livingstone, Edinburgh London, pp 127–146Google Scholar
  33. Oksche A, von Harnack M (1963) Elektronenmikroskopische Untersuchungen am Stirnorgan von Anuren (Zur Frage der Lichtrezeptoren). Z Zellforsch 59:239–288Google Scholar
  34. Oksche A, Vaupel-von Harnack M (1965) Elektronenmikroskopische Untersuchungen an den Nervenbahnen des Pinealkomplexes von Rana esculenta L. Z Zellforsch 68:389–426Google Scholar
  35. Omura Y, Ali MA (1980) Responses of pineal photoreceptors in the brook and rainbow trout. Cell Tissue Res 208:111–122Google Scholar
  36. Parker GH (1948) Animal colour changes and their neurohumors. Univ Press CambridgeGoogle Scholar
  37. Paul E, Hartwig HG, Oksche A (1971) Neurone und zentralnervöse Verbindungen des Pinealorgans der Anuren. Z Zellforsch 112:466–493Google Scholar
  38. Ueck M (1968) Ultrastruktur des pinealen Sinnesapparates bei einigen Pipidae und Discoglossiden. Z Zellforsch 92:452–476Google Scholar
  39. Ueck M (1979) Innervation of the vertebrate pineal. Progr Brain Res 52:45–88Google Scholar
  40. Wake K, Ueck M, Oksche A (1974) Acetylcholinesterase containing nerve cells in the pineal complex and subcommissural area of the frogs, Rana ridibunda and Rana esculenta. Cell Tissue Res 154:423–442Google Scholar

Copyright information

© Springer-Verlag 1981

Authors and Affiliations

  • H. -W. Korf
    • 1
  • R. Liesner
    • 1
  • H. Meissl
    • 2
  • A. Kirk
    • 2
  1. 1.Department of Anatomy and CytobiologyJustus Liebig University of GiessenGiessenGermany
  2. 2.Max Planck Institute for Physiological and Clinical ResearchBad NauheimGermany

Personalised recommendations