Antero Huhtala

Origin of myelinated nerves in the rat iris

Abstract In order to investigate the origin of myelinated fibres of the iris, albino rats were subjected to the following denervations: (1) extirpation of the ciliary ganglion, (2) extirpation of the superior cervical ganglion, and (3) stereotactic coagulation of the ophthalmic division of the trigeminal nerve. The animals were killed 7–21 days after the denervations and the myelinated nerves of the iris were studied with electron microscopy. Trigeminai neurotomy produced Wallerian degeneration in the myelinated fibres of the ipsilateral iris. After ciliary and superior cervical ganglionectomies the myelinated fibres of the iris remained intact. On the basis of these findings it would appear evident that only the ophthalmic division of the trigeminal nerve contributes myelinated nerve fibres to the rat iris and these fibres enter the iris exclusively via the long ciliary nerves.

Effects of denervations on the acetylcholinesterase-containing and fluorescent nerves of the rat iris.

The thiocholine method for the demonstration of AChE‐containing fibres and the formaldehyde‐induced fluorescence technique for the visualization of adrenergic fibres were employed to study the innervation of the albino rat iris. The following denervations were performed in order to verify the origins of different nerve types: (1) extirpation of the ciliary ganglion, (2) extirpation of the superior cervical ganglion, (3) stereotactic coagulation of the ophthalmic division of the trigeminal nerve, and (4) all possible combinations of the above‐mentioned procedures.

Wallerian degeneration of the myelinated nerves of cat iris after denervation of the ophthalmic division of the trigeminal nerve: an electron microscopic study

Abstract To confirm the central origin of the myelinated nerves of the cat iris, the ophthalmic division of trigeminal nerve was interrupted stereotactically using an intracranial approach. Damage to the third nerve was avoided. Absent blink-reflex and neuroparalytic keratitis appeared in the ipsilateral eye, whereas the other eye was normal. The cats were killed 1, 2, 3 or 5 days after denervation. The location of electrocoagulation was verified at autopsy by naked-eye examination and by studying the distal end of the trigeminal nerve electron microscopically. Electron micrographs revealed Wallerian degeneration in the myelinated nerves of the iris. Axonal changes were seen 2–3 days after denervation, and myelin sheath fragmentation appeared 5 days after denervation. Ultrastructure of myelinated nerves in the other eye was normal. The results suggest that the myelinated nerves of the iris are derived from the ophthalmic division of the trigeminal nerve.

Myelinated Nerves of Guinea Pig Iris after Denervation of the Ophthalmic Division of the Trigeminal Nerve

Myelinated nerves of the iris of 12 guinea pigs were studied light-microscopically after stereotactic denervation of the ophthalmic division of the trigeminal nerve. The trypsin digestion and bleaching technique for demonstration of myelinated nerves of the iris was used. After trigeminal denervation all myelinated nerves of the iris degenerated. This indicated that only somatic sensory nerves have myelin sheaths in the guinea pig iris.

Observations on the Nerves of the Cat Iris after Denervation of the Ophthalmic Division of the Trigeminal Nerve

The ophthalmic division of the trigeminal nerve was denervated stereotactically by electrocoagulation. Damage to the third nerve was avoided. Four days after denervation the homolateral iris was studi

Organization of the myelinated nerves in the cat iris

Abstract The trypsin digestion and bleaching technique, with PAS-haematoxylin or Sudan black staining, was used for demonstration of the architecture and organization of the myelinated nerves of the cat iris. The myelinated nerves enter the cat iris as several bundles in many places on the iris root. The ciliary part of the iris contains strongly-developed myelinated nerve bundles running radially or obliquely and having circular anastomoses. On division and intersection, the myelinated nerves dorm a finer plexus with a rhomboid mesh in the pupillary part. The myelinated nerves do not follow the iris vessels. They are arranged according to the course of the connective tissue fibres. The myelinated nerves of the cat iris were considered to be sensory.

Myelinated Nerves of the Guinea pig Iris

The organization of the myel inated nerves of the guinea pig iris was visualized by trypsin digestion and bleaching technique with PAS-haematoxylin or Sudan black staining. These nerves form a well-de