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.

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.     

Endothelial nerve fibres in the cornea of the frogRana ridibunda

Summary The ultrastructural study of the frog cornea revealed the existence of intraendothelial nerve fibres. These nerve fibres are unmyelinated elements but surrounded by cytoplasmic lamellae of Schwann cells.Supported by D.C.I.N.P. Grant 78-77.     

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.     

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.     

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.     

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.     

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     

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.     

Der elektrophysiologische Nachweis der propriozeptiven Muskelafferenz und des monosynaptischen Reflexbogens der inneren Kehlkopfmuskeln

Summary On excitation of the superior laryngeal nerve and the recurrent nerve with single square wave shocks in patients undergoing total exstirpation of the larynx for cancer, a reflex potential can be recorded from the vocal muscle. This potential shows the criteria characteristic of the reflex potential arising on excitation of muscle spindles or the afferents of muscle spindles (la-fibres) in limb muscles. The pathway of afferent fibres is for the main part via the sup. lar. nerve but there seems to be an indication of a small part of afferents in the recurrent nerve also.     

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.     

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.     

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.     

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.     

Immunocytology of alpha-endorphin positive hypothalamic fibers of Carassius auratus L. and Cyprinus carpio L.]

An immunocytological study of the basal hypothalamus of Carassius auratus and Cyprinus carpio with an alpha-endorphin antiserum shows the different nerve processes belonging probably to the immunoreactive cells of the lateral part of the N.L.T. According to their pathways, two main fibre tracts have been distinguished: many fluorescent fibres converge towards the pituitary gland into which they enter, other fibres run caudally through the tuber towards the nucleus tuberis inferior (Baumgarten and Braak) where they could not be followed further.     

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.     

Sekretomotorische Fasern und Endigungen in der Adenohypophyse

Summary We demonstrated, in the pituitary of the animals examined, fibres which emerge from the Tr. hypothalamo-hypophyseal system and enter partly into the Pars intermedia and partlyvia the Pars tubularis into the Pars distalis and take their course directly towards the glandular cells. In the Pars distalis the nerve fibres end around the glandular cells in a special pericellular net.     

Ricerche fisiologiche sulla distribuzione periferica del nervo depressore aortico destro nel cane

Summary The periferal distribution of the right aortic nerve has been studied in physiological experiments on the dog. It has been found that after section of both Hering's nerves and left vago-depressor trunk and after denervation of the baroceptor area ofMuratori-Nonidez lying at the root of the right subclavian artery, the electrical stimulation of one splancnic nerve or the intravenous injection of adrenaline still produces a reflex bradycardia; moreover the cooling of the vagus nerve still results in a rise of the blood pressure. It is inferred that a group of baroceptor fibres of the right aortic nerve originate from areas situated in the aortic region.