The organization of the extraocular motor nuclei in the Atlantic stingray, Dasyatis sabina.




Rosiles, J.R.
Leonard, R.B.

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Retrograde transport of HRP was used to determine the location and organization of the motor nuclei innervating the extrinsic eye muscles of the stingray, and elasmobrach fish. Oculomotor neurons are located both medial to and immediately ventrolateral to the MLF in the rostral midbrain. A ventral oculomotor nucleus was found among the IIIrd nerve rootlets close to the base of the midbrain. The dendrites of cells in the dorsal nucleus appear to be preferentially oriented in the transverse plane penetrating the MLF. Motorneuron pools innervating individual muscles are incompletely segregated in the dorsal group. However, the ventral nucleus innervates only the inferior oblique muscle. Dorsally, motorneurons innervating a single muscle are found on both sides of the MLF. In the caudal midbrain, the majority of trochlear motorneurons are scattered in the medulla from a ventrolateral position resembling the location of the nucleus in teleost fish to a dorsomedial position close to the MLF as in most other vertebrates. In contrast to other vertebrates, the medial rectus muscle is innervated by the contralateral oculomotor nucleus. Motorneurons innervating the other muscles have the same laterality as found in other vertebrates.


p. 677-687.


vertebrate zoology, stingrays, Dasyatis sabina, physiology, neurophysiology, marine fish