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The rat's postero‐orbital sinus hair: I. Brainstem projections and the effect of infraorbital nerve section at different ages
Author(s) -
Waite Phil M. E.,
de Permentier Patrick
Publication year - 1991
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903120302
Subject(s) - infraorbital nerve , anatomy , brainstem , trigeminal nerve , lingual nerve , biology , nucleus , maxillary nerve , medicine , neuroscience , pathology , alternative medicine , tongue
The central terminations, in the trigeminal nucleus, of afferents from the rat's postero‐orbital (PO) sinus hair have been investigated with transganglionic transport of horseradish peroxidase (HRP) and succinic dehydrogenase (SDH) histochemistry. The normal pattern of terminations has been compared with that found after section of an adjacent nerve, the infraorbital (IO) nerve, at three ages: neonatal, 1 week old, and adult. The PO afferent fibres have three separate representations in the brainstem‐in trigeminal sensory nucleus principalis (Vp) and rostral subnucleus oralis (Vo), in trigeminal subnucleus interpolaris (Vi), and in caudal trigeminal subnucleus caudalis (Vc) and C 1 dorsal horn. In coronal sections the areas of terminations were seen as oval patches lying ventrolaterally in Vp, Vo, and Vi and ventromedially in Vc and C 1 . Following neonatal IO nerve section the terminal areas were approximately doubled in Vp, Vo, and Vi but were unchanged in Vc and C 1 . IO nerve section at day 7 also caused a significant, though smaller (1.4× compared with 2.0×), increase in the terminal areas in the rostral three nuclei, without changing Vc and C 1 . However, no significant change in area occurred after adult IO nerve section. SDH histochemistry at 3 to 4 weeks of age showed patches of terminals on both normal and lesioned sides consistent with those seen after HRP. Previous studies have reported increased functional representation of surrounding intact skin regions, including the PO sinus hairs, after neonatal but not adult, IO nerve section. The present results show that there are concomitant anatomical changes. Like the functional results, the extent of the anatomical changes are dependent on the maturity of the rat when lesioned.