Ultrastructural observations on the central innervation of the guinea-pig pineal gland.
In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between hypothalamus, epithalamus and the pineal gland.
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D004805:Ependyma / Q000648:ultrastructure; D006168:Guinea Pigs; D008297:Male; D008854:Microscopy, Electron; D009412:Nerve Fibers / Q000648:ultrastructure*; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure; D010870:Pineal Gland / Q000648:ultrastructure*; D013569:Synapses / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure