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Biomedical subjects

H Mannen

Publications and source records attributed to H Mannen.

At least 55 records · Page 3Linked to original sources
PubMed1987

Morphology of expiratory neurons of the Bötzinger complex: an HRP study in the cat.

In anesthetized and artificially ventilated cats, the physiological and morphological properties of expiratory neurons or their axons of the Bötzinger complex (BOT) were studied using intracellular recording and intracellular HRP labeling techniques. Thirteen expiratory neurons (nine cell somata and four axons) were successfully stained. Four of them were motoneurons, having relatively large cell somata in the retrofacial nucleus (RFN) and axons without any collaterals inside the brainstem. All the motoneurons showed a plateau shape of depolarization potentials during the expiratory phase. Any of the other nine expiratory neurons exhibited augmenting type firing or membrane potential changes during the expiratory phase. In five out of nine augmenting neurons, cell somata were stained and located ventral to the RFN. In four, only axons were stained. The majority of the augmenting neurons had two major axonal branches: one traveling toward the contralateral side and the other descending ipsilaterally in the brainstem. The most striking feature of the axonal trajectory was that all of the stained augmenting expiratory neurons, including the axons, had collateral branches with synaptic boutons in the BOT area, thus indicating that BOT expiratory neurons interact with some respiratory neurons in the BOT area and its vicinity.

Animals↗
PubMed1982

Central course and terminal arborizations of single primary vestibular afferent fibers from the horizontal canal in the cat.

Physiologically identified single primary vestibular afferents originating from the horizontal canal in the cat were intraaxonally stained with horseradish peroxidase. All afferents examined gave off one collateral to the interstitial nucleus of Cajal located in the vestibular root bundle in the brainstem. Then these fibers bifurcated into ascending and descending branches in the lateral vestibular nucleus. The ascending branch distributed terminals mainly in the middle part of the superior vestibular nucleus. The descending branch issued several collaterals in the ventrolateral regions of the lateral and inferior vestibular nuclei. These collaterals ran horizontally and reached the medial vestibular nucleus. Terminals were observed mainly in the boundaries between the medial nucleus and the lateral or inferior nucleus. Two types of primary vestibular afferents may be distinguished. Type A fibers had terminal arborizations with plenty of boutons en passage and boutons terminaux, while type B fibers those with a few boutons. The axonal diameter of the main trunk was smaller in type A fibers than in type B fibers.

Afferent Pathways↗
PubMed1981

Morphological analysis of astrocytes in the bullfrog (Rana catesbeiana) spinal cord with special reference to the site of attachment of their processes.

An attempt was made to elucidate the morphological features of astrocytes in the bullfrog spinal cord by means of a combination of electron microscopy, the Golgi method, and the intravascular dye injection method. Astrocytic somata are densely concentrated both in the wall of the central canal and in its proximity, and diffusely distributed in the intermediate and the ventral part of the gray matter. The most complicated and densest vascular network is found in the dorsal part of the gray matter. There is little correlation between the density of the distribution of astrocytic somata and that of the vascular network. Each astrocyte emits one process and ramifies by repeated bifurcations as it approaches the white matter or enters it. All these branching processes reach the pial surface of the spinal cord (the principal processes). Total rostrocaudal extent of their ramification is within 400 micron. A great number of small lateral offshoots (the secondary processes) arise both from the somata and the principal processes. Electron microscopy of vessel walls and the pial surface revealed that the principal processes attach to the subpial basement membrane with a specialized structure, an electron-dense layer, while the secondary processes merely surround blood vessels in a mode of juxtaposition. Comparison between amphibian and mammalian astrocytes is made regarding the site of attachment of their processes.

Animals↗
PubMed1980

Axonal branches and terminations in the cat abducens nucleus of secondary vestibular neurons in the horizontal canal system.

Single vestibular neurons functionally identified as secondary neurons receiving primary afferents from the horizontal canal in the cat were intracellularly stained with horseradish peroxidase (HRP). The vestibular neurons projecting to the ipsilateral abducens nucleus distributed terminal branches in a relatively narrow band in the nucleus. The stem axon of contralaterally projecting vestibular neurons bifurcated into ascending and descending branches in the contralateral medial longitudinal fasciculus. The collaterals emerging from these branches distributed terminals in a relatively wide area in the abducens nucleus. Collateral branches extended into the medial vestibular nucleus, prepositus hypoglossi nucleus and reticular formation.

Abducens Nerve↗
PubMed1979

Trajectory of group Ia afferent fibers stained with horseradish peroxidase in the lumbosacral spinal cord of the cat: three dimensional reconstructions from serial sections.

A reconstruction was made of the intramedullary trajectory of 23 physiologically identified Ia afferents from cat hind limb muscles (medial gastrocnemius, soleus, plantaris, flexor digitorum-hallucis longus, and hamstring). The afferents were stained by intra-axonally injected HRP. The axons of these afferents were traced over distances of 5.8 mm to 15.7 mm rostrocaudally. In the dorsal funiculus fibers from all the muscles showed a similar course and similarly bifurcated into an ascending and a descending branch. The mean diameters of stem axons, ascending branches, and descending branches were 6.6 micrometer, 5.8 micrometer, and 3.0 micrometer, respectively. Within the analyzed lengths of the spinal cord five to eleven collaterals were given off from the two branches. The distances between adjacent collaterals of the ascending and descending branches averaged 1200 micrometer and 790 micrometer, respectively. The collaterals as a rule passed through the medial half of the dorsal horn before they entered the deeper parts of the gray matter. The terminal distribution areas common to all Ia collaterals were: (1) the medial half of the base of the dorsal horn, mainly lamina VI: (2) lamina VII; and (3) lamina IX. The numbers of terminals were largest in lamina IX and smallest in lamina VII. The density of terminals in lamina IX was highest in the homonymous motor cell column. The terminal distribution areas of adjacent collaterals showed no overlap in the sagittal plane. Terminal branches carried one bouton terminal and up to six boutons en passage with an average of 1.8 terminals per terminal branch. Apparent axosomatic and axodendritic contacts were seen on small-sized and medium-sized neurons in laminae V-VI, medium-sized neurons in lamina VII, and large neurons in lamina IX. One motoneurons was contacted by an average of 3.3 terminals. In addition to the common features, Ia collaterals of various muscles of origin showed some differences in their trajectories in the ventral horn, and in their terminations in the gray matter.

Animals↗
PubMed1978

Reconstruction of trajectory of primary afferent collaterals in the dorsal horn of the cat spinal cord, using Golgi-stained serial sections.

Using Golgi-stained serial sections obtained at the sacro-caudal levels of the cat spinal cord, it was possible to reconstruct the trajectory of primary afferents. They were classified into two groups: reliable primary afferents directly traced from the dorsal root and probable primary afferents traced from the dorsal funiculus or Lissauer's tract. The diameters of the reliable primary afferents vary from 0.88-1.88 mum. According to their courses, reliable primary afferents as well as probable primary afferents were classified into three groups: the first is distributed to both medial and lateral halves of the dorsal horn, the second to the medial half, and the third to the lateral half. Commissural fibers were also observed among the probable primary afferents. The rostro-caudal and medio-lateral extents of reliable primary afferents are found to be between 250 and 950 mum and 270 and 700 mum respectively, while those of the probable primary afferents were between 125 and 670 mum and 270 and 1,640 mum respectively. These primary afferent fibers are connected with at least two or more laminae of the dorsal horn gray matter.

Afferent Pathways↗
PubMed1976

Reconstruction of neurons of dorsal horn proper using Golgi-stained serial sections.

Three neurons located in the dorsal horn (Lamina III) have been reconstructed using Golgi-stained serial sections. These cells including dendritic and axonal branchings appear to remain within the dorsal horn and to belong to small-sized local interneurons of the dorsal horn proper. The measurements have been made with various criteria: the medio-lateral, dorso-ventral and rostro-caudal extents of the dendritic tree as well as the axonal branchings, total dendritic and axonal length, number of axonal endings and distance from the starting point of the axon at the dendrite to the point where the dendrite joins the soma (S-A distance).

Animals↗
PubMed1975

Reconstruction of axonal trajectory of individual neurons in the spinal cord using Golgi-stained serial sections.

A procedure bringing the axonal and dendritic cut ends found in the confronting planes of the serial sections face to face by means of serial photomicrographs provides a means for precisely reconstructing individual Golgiimpregnated neurons. Utilizing this method, it was possible to follow at the caudal level of a kitten's spinal cord the total course of the axons and dendrites of sixteen intramedullary neurons. The neurons located in the dorsal horn (laminae IV and V) send their long ascending axon into the lateral funiculus of the ipsi- or contralateral side, and, in one case, into the anterior funiculus of the ipsilateral side, giving off on the way several collaterals to the dorsal half of lamina VII of the ipsi- or contralateral side. Some of the neurons found in the intermediate region and the ventral horn (laminae VII, VIII and X) distribute their axonal branches in the intermediate region or the ventral horn of the ipsi- or contralateral side or both sides, running throughout their course in the grey matter, while the others act in the same manner by way of the lateral or anterior funiculi. Axonal and collateral endings terminate with small terminal knobs. The total axonal length of the neurons observed, with the exception of some with a long ascending trajectory, varies from 1,680 mum to 6,480 mum.

Animals↗