Summary
Ultrastructural details of neuron-like cells as well as synaptic nerve endings in the pineal gland of the ground squirrel are described. The neuronlike cells are situated mainly in the distal portion of the gland. Since the neuron-like cells differ considerably from the pinealocytes and exhibit cytological features characteristic of nerve cells, they are presumably true neurons. The cell bodies or processes of the neuron-like cells receive many synapses. The nerve endings synapsing on these cells contain numerous small non-granulated and some large granulated vesicles but no small granulated vesicles. These synaptic nerve endings are rather abundant within the parenchyma but they are also found in perivascular spaces ensheathed completely or partially by the Schwann cell cytoplasm. Similar nerve endings occasionally make typical synaptic contacts with the cell bodies or processes of the pinealocytes. Since the adrenergic nerve endings do not form synapses on the pinealocytes in the ground squirrel, it is clear that nerve endings other than adrenergic ones also distribute within the pineal gland of this animal. These synaptic nerve endings may contribute, at least to some extent, to the innervation of the ground squirrel pineal gland, whether they are derived from the nerve fibers penetrating the pineal gland or from the neuron-like cells.
Similar content being viewed by others
References
Bargmann, W. Die Epiphysis cerebri. In: Handbuch der Mikroskopischen Anatomie des Menschen, VI/4, pp. 309–502. Berlin: Springer. 1943.
Collin, J.-P. Differentiation and regression of the cells of the sensory line in the epiphysis cerebri. In: The pineal gland (Wolstenholme, G. E. W., Knight, J., eds.), pp. 79–120. Edinburgh-London: Churchill Livingstone. 1971.
David, G. F. X., Herbert, J. Experimental evidence for a synaptic connection between habenula and pineal ganglion in the ferret. Brain Res.64, 327–343 (1973).
David, G. F. X., Herbert, J., Wright, G. D. S. The ultrastructure of the pineal ganglion in the ferret. J. Anat.115, 79–97 (1973).
Gray, E. G. Electron microscopy of presynaptic organelles of the spinal cord. J. Anat.97, 101–106 (1963).
Hartmann, F. Über die Innervation der Epiphysis cerebri einiger Säugetiere. Z. Zellforsch.46, 416–429 (1957).
Kenny, G. C. T. The “nervus conarii” of the monkey. (An experimental study.) J. Neuropath, exp. Neurol.20, 563–570 (1961).
Le Gros Clark, W. E. The nervous and vascular relations of the pineal gland. J. Anat.74, 470–492 (1940).
Levin, P. M. A nervous structure in the pineal body of the monkey. J. comp. Neurol.68, 405–409 (1938).
Matsushima, S., Reiter, R. J. Comparative ultrastructural studies of the pineal gland of rodents. In: Ultrastructure of endocrine and reproductive organs (Hess, M., ed.), pp. 335–356. New York: J. Wiley. 1975 a.
Matsushima, S., Reiter, R. J. Ultrastructural observations of pineal gland capillaries in four rodent species. Am. J. Anat.143, 265–282 (1975 b).
Matsushima, S., Reiter, R. J. Fine structural features of adrenergic nerve fibers and endings in the pineal gland of the rat, ground squirrel and chinchilla. Am. J. Anat.148, 463–478 (1977).
Povlishock, J. T., Kriebel, R. M., Seibel, H. R. A light and electron microscopic study of the pineal gland of the ground squirrel, Citellus tridecemlineatus. Am. J. Anat.143, 465–484 (1975).
Romijn, H. J. Structure and innervation of the pineal gland of the rabbit,Oryctolagus cuniculus (L.). I. A light microscopic investigation. Z. Zellforsch.139, 473–485 (1973).
Romijn, H. J. Structure and innervation of the pineal gland of the rabbit,Oryctolagus cuniculus (L.). III. An electron microscopic investigation of the innervation. Cell Tiss. Res.157, 25–51 (1975).
Spurr, A. R. A low-viscosity epoxy resin embedding medium for electron microscopy. J. Ultrastruct. Res.26, 21–43 (1969).
Trueman, T., Herbert, J. Monoamines and acetyl-cholinesterase in the pineal gland and habenula of the ferret. Z. Zellforsch.109, 83–100 (1970).
Wood, J. G. The effects of niamid and reserpine on the nerve endings of the pineal gland. Z. Zellforsch.145, 151–166 (1973).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Matsushima, S., Reiter, R.J. Electron microscopic observations on neuron-like cells in the ground squirrel pineal gland. J. Neural Transmission 42, 223–237 (1978). https://doi.org/10.1007/BF01675312
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01675312