Variation in the number and size of myelinated nerve fibers regenerated after repeated localized freezing of the sciatic nerve of rats]

The number and size of myelinated fibres have been determined in the nerve to medial head of the gastrocnemius muscle of Rats in which the sciatic nerve had been frozen locally 1 to 5 times at monthly intervals. The contralateral nerve was used as a control. When the measurements were made one month after the last freezing, the number of fibres increased progressively until the 3rd freezing, reaching about 220% of the normal value. No higher values were observed after 4 or 5 freezings. The mean diameter of fibres decreased with the number of operations. When the measurements were made 3, 6, 12 or 18 months after the 3rd freezing, the number of fibres decreased by about 30% between the 1st and the 3rd month and then stabilized. The mean diameter of fibres increased progressively. However, at the 18th month, the size of the myelinated fibres had not reached the normal value.     

Pathways for excitatory and inhibitory innervation to the guinea-pig tracheal smooth muscle

Summary The trachea receives excitatory cholinergic innervation from the vagus nerve and the stellate ganglion. Inhibitory adrenergic fibres have the same sources. Those in the vagus nerve probably derive from high vagosympathetic anastomoses. Nonadrenergic inhibitory fibres have a preganglionic vagal supply.This study has been supported by grants from Magnus Bergvall Memorial Found and Harald and Greta Jeansson Foundation.     

Pathways for excitatory and inhibitory innervation to the guinea-pig tracheal smooth muscle.

The trachea receives excitatory cholinergic innervation from the vagus nerve and the stellate ganglion. Inhibitory adrenergic fibres have the same sources. Those in the vagus nerve probably derive from high vagosympathetic anastomoses. Nonadrenergic inhibitory fibres have a preganglionic vagal supply.     

Degeneration of unmyelinated axons in the dental root canal induced by 6-OH-dopamine

Summary The pulpal nerve fibres of feline incisors were examined ultrastructurally after i.v. administration of 6-OH-dopamine. The presence of degenerating unmyelinated fibres at this site provides conclusive morphological evidence that sympathetic fibres enter the dental pulp.     

Peripheral sympathetic innervation of the deep pineal gland of the golden hamster

Summary Both the superficial and deep pineal components of the intact hamster contain a rich network of green to yellow-green fluorescent nerve fibres. After either superior cervical ganglionectomy or after transection of the nervi conarii the majority of the fluorescing fibres disappeared from both the superficial and deep pineal mases. Although the deep pineal remained intact after surgical removal of the superficial pineal, it was devoid of any green or yellowgreen fluorescent fibres.Supported by NSF Grant No. BMS74-06275A01     

Immunohistochemical localization by electron microscopy of GnRH in the median eminence of Xenopus laevis daud]

Using antibodies against mammalian LHRH with the unlabeled antibody enzyme method immunoreactive nerve fibres were localized in the median eminence of Xenopus laevis at the electron microscopic level. These fibres contain irregularly shaped neurosecretory granules with an average diameter of 890 A.     

Sympathetic preganglionic pupillodilator fibres in the light reflex

Summary The modifications of the sympathetic pupillodilator activity in the light reflex have been demonstrated by recording the electrical discharge of single preganglionic fibres in the cervical sympathetic nerve.This work was supported by a grant of CNR.     

Zum Vorkommen von RNS im Nervenfaserbereich

Summary The incorporation of 3H-uridine into the RNA of the perikaryal and fibrous region of the optic tectum of the fish brain was investigated by means of radioautography after incubation times of 11 min to 96 h. There is no transport of RNA from the cell body to the nerve fibres. After RNase-treatment 90% of perikaryal RNA-labelling is washed out, but only a very small amount of the previous very few labelling of the nerve fibres.     

Geschwindigkeit der Nervenleitung innerhalb der Netzhaut

Summary The conduction velocity of the unmyelinated portion of the optic nerve fibres within the cat's retina was measured by shifting a microelectrode from the blind spot outwards and stimulating antidromically in the lateral geniculate body. The mean conduction velocities were 2.8 m/s for the fast, and 1.7 m/s for the slow group of optic nerve fibres, as compared with maxima of 70 and 23 m/s respectively for the same groups in the myelinated extrabulbar portion.     

Effects of increased potassium in scala tympani on auditory nerve sensitivity.

Raising the K+ concentration in scala tympani of the guinea-pig cochlea generally caused a substantial increase in the spontaneous firing rate of single auditory nerve fibres. This effect was not accompanied by any observed reduction in the threshold sensitivity of these fibres. These findings cast doubt on current theories of cochlear transduction.     

Innervation of the ovarian interstitial cell of the chick embryo.

Electron microscopic examination of the developing ovary of 15-20-day chick embryos revealed that the interstital cells well innervated. Nerve fibres and nerve endings were observed in close contact with steroid-producing cells.     

A simple silver nitrate impregnation of nerve fibres with preservation of acetylcholinesterase activity at the motor end-plate

A rapid silver nitrate impregnation of nerve fibres has been devised to maintain a histochemically detectable acetylcholinesterase activity at the motor end-plates.     

Innervation of the ovarian interstitial cell of the chick embryo

Summary Electron microscopic examination of the developing ovary of 15–20-day chick embryos revealed that the interstitial cells were well innervated. Nerve fibres and nerve endings were observed in close contact with steroid-producing cells.     

Effects of increased potassium in scala tympani on auditory nerve sensitivity

Summary Raising the K⁺ concentration in scala tympani of the guinea-pig cochlea generally caused a substantial increase in the spontaneous firing rate of single auditory nerve fibres. This effect was not accompanied by any observed reduction in the threshold sensitivity of these fibres. These findings cast doubt on current theories of cochlear transduction.G. Leng was supported by the S.R.C.     

The level of noradrenaline in terminals and varicosities after the ligation performed in the sympathetic ground-plexus

Summary It is well-known that the ligation of nerve trunk induces an intensive accumulation of noradrenaline proximally to the ligation. A similar ligation, performed in the sympathetic ground-plexus, induces no changes in the segments of terminal fibres situated proximally.     

The level of noradrenaline in terminals and varicosities after the ligation performed in the sympathetic ground-plexus

It is well-known that the ligation of nerve trunk induces an intensive accumulation of noradrenaline proximally to the ligation. A similar ligation, performed in the sympathetic ground-plexus, induces no changes in the segments of terminal fibres situated proximally.     

A simple silver nitrate impregnation of nerve fibres with preservation of acetylcholinesterase activity at the motor end-plate

Summary A rapid silver nitrate impregnation of nerve fibres has been devised to maintain a histochemically detectable acetylcholinesterase activity at the motor end-plates.We thank Mrs Paulette Cloup and Mr D. Levieux for their valuable technical assistance.     

Role of grafted Schwann cells in the regeneration of intraspinal nerve fibers when peripheral nerve, skeletal muscle or submandibular gland fragments are transplanted into the spinal cord of the mouse

Small pieces of peripheral nerve, skeletal muscle or submandibular gland, taken from young or new-born mice, were grafted into the non-transected spinal cord of young albino mice, at the thoracic level, through a punctiform meningeal opening. Neighbouring intraspinal nerve fibres, severed during the grafting process, regenerate into and eventually throughout the transplants. In this regenerative process, sedentary or migrating Schwann cells of the transplants probably have a prominent influence in guiding the growth of the axonal sprouts they ensheathe and eventually myelinate.     

Do peripheral nerves contain a factor inducing acetylcholine sensitivity in skeletal muscle?

A crude extract of the sciatic nerve, eluate of dialyzed nerve extract or 2 folin-positive sephadex fractions induced acetylcholine sensitivity of extrajunctional regions in extensor digitorum longus muscle fibres of the rat, when released from silastic plates implanted for 3--4 days onto the muscle surface.