+ Translate

Evidence suggesting that both the cortico pontine and cerebello pontine systems are each composed of 2 separate neuronal populations an electron microscopic and horseradish peroxidase study in the rat

, : Evidence suggesting that both the cortico pontine and cerebello pontine systems are each composed of 2 separate neuronal populations an electron microscopic and horseradish peroxidase study in the rat. Journal of Comparative Neurology 195(2): 221-242

Evidence from horseradish peroxidase (HRP) and EM studies suggests that both the corticopontine and cerebellopontine systems each arise from 2 separate populations of neurons within their respective sites of origin. Following injection of HRP into the pontine nuclei using a ventral approach, labeled neurons in sensorimotor cortex included the large pyramidal cells deep in layer Vb and small-to-intermediate-sized neurons located more superficially in Vb. Previous studies (Wise and Jones) showed that these same large pyramidal neurons give rise to fibers of the corticospinal system while smaller more superficial cells project either to various brainstem locations or to the spinal cord. HRP-positive neurons were observed in visual cortical areas where they were again restricted to layer Vb, which is the source of cells projecting to the superior colliculus and pulvinar (Gilbert and Kelley; Lund, et al.). The corticopontine projection apparently consists of collateral terminations of the corticospinal system as well as branches of a corticofugal system which arises from neurons in sensorimotor and visual cortices and projects primarily to certain brainstem locations. EM studies revealed that following sensorimotor or visual cortex lesions both filamentous and dark degenerating boutons were evident in the pons. The small dark boutons terminated distally on pontine neurons and predominated after sensorimotor lesions while the larger filamentous endings contacted more proximal parts of pontine neurons and predominated after visual cortex lesions. Similar results were obtained in studies of the cerebellopontine system. Basilar pontine HRP injections resulted in the labeling of cells in each of the cerebellar nuclei, the majority of which were classified as medium-to-large multipolar neurons while a lesser number appeared to be smaller fusiform or spindle-shaped cells. After interruption of cerebellopontine axons in the brachium conjunctivum, many large filamentous degenerating boutons were observed in contact with a characteristic cluster of dendritic spines as well as somata and dendritic shafts. A lesser number of small boutons undergoing the typical dark type of degeneration were in opposition to singular, small dendritic shafts. The combination of HRP and EM observations suggests that the cerebellopontine system, like the corticopontine system, consists of 2 neuronal elements: larger multipolar neurons giving rise to the large boutons which form the central element in a characteristic synaptic complex and undergo filamentous degeneration, and smaller neurons whose axons terminate as the small boutons which contact only small dendritic profiles and do not participate in the synaptic complexes.

(PDF 0-2 workdays service)

Accession: 005411899

Submit PDF Full Text: Here

Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:

Related references

Mihailoff, G.A.; Watt, C.B.; Burne, R.A., 1981: Evidence suggesting that both the corticopontine and cerebellopontine systems are each composed of two separate neuronal populations: an electron microscopic and horseradish peroxidase study in the rat. Journal of Comparative Neurology 195(2): 221-242

Hollander, H.; Brodal, P.; Walberg, F., 1969: Inst electron microscopic observations on the structure of the pontine nuclei and the mode of termination of the cortico pontine fibers an experimental study in the cat. Experimental Brain Research 7(2): 95-110

Mihailoff G.A.; Watt C.B., 1979: The dual nature of cortical and cerebellar inputs to the basilar pontine nuclei in the rat a horseradish peroxidase electron microscopic degeneration and combined golgi electron microscopic analysis. Anatomical Record 193(3): 623

Watt, C.B.; Mihailoff, G.A., 1983: The cerebello pontine system in the rat 2. electron microscopic studies. Cerebellopontine axonal boutons in the neuropil of the basilar pontine nuclei (BPN) were marked for ultrastructural identification by producing unilateral electrolytic lesions of the superior cerebellar peduncle (SCP) as it exited from the cerebel...

Trojanowski J.Q.; Gonatas J.O.; Gonatas N.K., 1981: A light microscopic and electron microscopic study of the intra neuronal transport of horseradish peroxidase and wheat germ agglutinin peroxidase conjugates in the rat visual system. The ability of horseradish peroxidase (HRP) and the lectin wheat germ agglutinin (WGA) covalently conjugated with HRP to label retrogradely dorsal lateral geniculate nucleus (dLGN) neurons, subsequent to injections of either marker into rat striat...

Hitselberger W.E.; House W.F., 1973: Micro topography of the cerebello pontine angle and early otologic diagnosis of cerebello pontine angle tumors. Schuermann, K And Et Al (Ed ) Advances in Neurosurgery, Vol 1 Brain Edema: Pathophysiology And Therapy; Cerebello Pontine Angle Tumors: Diagnosis And Surgery Symposium, Mainz, West Germany, April 30-May 3, Xvi+385p Illus Springer-Verlag: Berlin, West Germany; New York, N Y , U S A 203

Bjaalie J.G.; Brodal P., 1983: Visual field representation in the cortico pontine projection from area 17 as determined with retrograde transport of horseradish peroxidase wheat germ agglutinin. Neuroscience Letters (SUPPL 14): S30

Atkinson, W.J., 1949: The anterior inferior cerebellar artery; its variations, pontine distribution, and significance in the surgery of cerebello-pontine angle tumours. Journal of Neurology, Neurosurgery, and Psychiatry 12(2): 137-151

Border B.G.; Kosinski R.J.; Azizi S.A.; Mihailoff G.A., 1986: Certain basilar pontine afferent systems are gamma aminobutyric acid ergic combined horseradish peroxidase studies in the rat. Injection of the tracer substance wheat germ agglutinin-horseradish peroxidase (WGA-HRP) directly into the basilar pontine nuclei using a ventral surgical approach resulted in the labeling of somata in many areas both rostral and caudal to the bas...

Woodruff, M.L.; Baisden, R.H.; Whittington, D.L.; Kelly, J.E., 1986: Inputs to the pontine A5 noradrenergic cell group: a horseradish peroxidase study. The noradrenergic A5 cell group of the caudal ventrolateral pons has been implicated in regulation of cardiovascular activity. The efferent fibers from this cell group have been established, but the sources of afferents into the region have not. H...