Visceral and orofacial somatic afferent fiber terminals converge onto the same neuron in paratrigeminal nucleus: An electron microscopic study in rats.
The paratrigeminal nucleus (Pa5) receives visceral sensory inputs through the vagus (X) and glossopharyngeal (IX) nerves and somatic sensory inputs through the trigeminal (V) nerve. In the present study, transganglionic transport of the WGA-HRP and Wallerian degeneration was used to identify whether two kinds of primary afferent fiber terminals converge onto a single neuron in the Pa5 at the utrastructural level. It was found that HRP-labeled and degenerated terminals originating from the IX and/or X nerves and infraorbital nerve formed asymmetrical synapses with unlabeled dendrites in the Pa5. Furthermore, approximately 7% (43/630) HRP-labeled and 31% (43/137) degenerated terminals formed synaptic connections with the same dendritic profiles simultaneously in the dorsal division of the Pa5. These results may provide a neuroanatomical substrate for integration of viscerosomatic sensory inputs associated with visceral and cardiovascular reflexes in the Pa5.
Ma
Wen-Ling
WL
Department of Anatomy and K K Leung Brain Research Centre, Fourth Military Medical University, Xi'an 710032, P R China. Ma_wlmail@sohu.com
Zhang
Wen-Bin
WB
Xiong
Kang-Hui
KH
Guo
Feng
F
D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D005830:Geniculate Ganglion / Q000502:physiology; D005930:Glossopharyngeal Nerve / Q000502:physiology; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009475:Neurons, Afferent / Q000502:physiology* / Q000648:ultrastructure*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014278:Trigeminal Nuclei / Q000166:cytology*; D014630:Vagus Nerve / Q000502:physiology; D014855:Wallerian Degeneration / Q000473:pathology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate / Q000378:metabolism
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate