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Organization of the six motor nuclei innervating the ocular muscles in lamprey
Author(s) -
Fritzsch B.,
Sonntag R.,
Dubuc R.,
Ohta Y.,
Grillner S.
Publication year - 1990
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.902940402
Subject(s) - oculomotor nucleus , anatomy , abducens nucleus , biology , extraocular muscles , oculomotor nerve , trochlear nerve , superior oblique muscle , lamprey , abducens nerve , medial rectus muscle , lateral rectus muscle , nucleus , superior rectus muscle , lampetra , midbrain , neuroscience , central nervous system , medicine , alternative medicine , pathology , fishery , palsy
The topography of motoneurons supplying each of the six ocular muscles of the lamprey, Lampetra fluviatilis , was studied by selective application of HRP to the cut nerves of identified muscles. In addition, the distributions of motoneuron populations to both eyes were studied simultaneously with fluoresceine and rhodamine coupled dextran‐amines (FDA and RDA) applied to cut ocular muscle nerves of either side. The motoneuron pool of the caudal oblique muscle is represented bilaterally in the trochlear (N IV) motor nucleus. The dorsal rectus muscle is innervated from a contralateral group of oculomotor (N III) motoneurons and the remaining four muscles exclusively from the ipsilateral side (N III and N VI). The inferior and posterior rectus muscles are both innervated by the abducens nerve. In contrast to all jawed vertebrates, only three eye muscles (the dorsal rectus, rostral rectus, and rostral oblique) are innervated by the oculomotor nerve in lampreys (N III). Lampreys have a motor nucleus similar to the accessory abducens nucleus previously described only in tetrapods. They lack the muscle homologous to the nasal rectus muscle of elasmobranchs and the medial rectus muscle of osteognathostomes. The distribution of the dendrites of different groups of motoneurons was studied and is considered in relation to inputs from tectum and the different cranial nerves.