Biomedical subjects

B Heppelmann

Publications and source records attributed to B Heppelmann.

45 records · Page 3Linked to original sources

PubMed1990

Ultrastructural three-dimensional reconstruction of group III and group IV sensory nerve endings ("free nerve endings") in the knee joint capsule of the cat: evidence for multiple receptive sites.

The noncorpuscular endings ("free nerve endings") of thinly myelinated group III and nonmyelinated group IV afferent nerve fibers have been examined in the knee joint capsule of sympathectomized cats by transmission electron microscopy and three-dimensional reconstruction of series of semi- and ultrathin sections. The sensory ending is the most distal part of a group III or IV nerve fiber that consists only of the sensory axon and associated Schwann cells but lacks a myelin sheath and is not surrounded by perineurium. The sensory axon divides into several branches and forms a terminal tree. The branches run either as single fibers or within small Remak bundles in parallel to sensory axons of other endings; they spread along vessel walls and also extend into dense connective tissue. Each sensory axon consists of a series of spindle-shaped thick segments ("beads") connected by waist-like thin segments. Thus all axons of sensory endings have a string-of-beads appearance, which resembles that of efferent sympathetic nerve fibers. The beads of the sensory axon and the end bulb at its tip show the same ultrastructural features which are characteristic of receptive sites: an accumulation of mitochondria and glycogen particles and various vesicles in the axoplasm and "bare" areas of axolemma that are not covered by Schwann cell processes. Group III and group IV sensory endings differ in the length of their branches (up to 200 microM in group III vs. more than 300 microM in group IV), number of beads per 100 microM axon length (about seven vs. nine or ten), mean diameter of axons (0.9-1.5 microM vs. 0.3-0.6 microM), and the presence of a neurofilament core consisting of bundles of parallel microfilaments only in group III. In conclusion, we propose that the sensory part of noncorpuscular "free nerve endings" is formed by the entire terminal tree of group III or group IV nerve fibers and that the beads in the course of the sensory axon represent multiple receptive sites.

Animals↗

PubMed1990

Origin of sympathetic innervation of the knee joint in the cat: a retrograde tracing study with horseradish peroxidase.

In the cat the origin of sympathetic nerve fibers in the medial and posterior articular nerve (MAN and PAN) of the knee joint was studied using retrograde labeling with horseradish peroxidase (HRP). Three to 5 days after uptake of HRP by MAN per cat 404 +/- 136 labeled somata (mean +/- S.D., n = 4 cats) were found mainly in the paravertebral ganglia L4 and L5 of the ipsilateral sympathetic trunk, and uptake of HRP by PAN labeled per animal 532 +/- 155 cell bodies (mean +/- S.D., n = 4 cats) mainly in the paravertebral ganglia L5 and L6. The cross-sectional areas of the labeled somata ranged from 200 to 1300 microns 2 with a mean of about 620 microns 2.

Adrenergic Fibers↗

PubMed1989

Serial sectioning, electron microscopy, and three-dimensional reconstruction of fine nerve fibres and other extended objects.

Two different techniques for three-dimensional reconstructions of nerve fibres or other extended fine tissue structures were developed to study the afferent innervation of the cat's knee-joint capsule. The re-embedding technique starts with series of semithin sections for light microscopic reconstructions. In a second step, selected semithin sections can be re-embedded for ultramicrotomy to examine ultrastructural details. This method offers the possibility to investigate fine structures over a distance of several hundred micrometres without any loss of ultrastructural information. The serial section-ESI technique is based on the electron spectroscopic imaging of semithin sections. Small tissue blocks are cut into series of either semithin or alternate semi- and ultrathin sections which can be directly used for a complete ultrastructural investigation. Finally, true-to-scale three-dimensional reconstructions are performed by graphical techniques or computer-aided methods.

Afferent Pathways↗

PubMed1988

The projection of the medial and posterior articular nerves of the cat's knee to the spinal cord.

We studied the spinal projections of the medial and posterior articular nerves (MAN and PAN) of the knee joint in the cat with the aid of the transganglionic transport of horseradish peroxidase. The afferent fibers of the MAN entered the spinal cord via the lumbar dorsal roots L5 and L6 and those of the PAN entered via the dorsal roots L6 and L7. Within the dorsal root ganglia, most labeled neurons had small to medium diameters. A relatively higher number of medium-size cell bodies were labeled from the PAN than from the MAN. In the spinal cord labeled MAN afferent fibers and terminations were most dense in the L5 and L6 segments, and those of the PAN were most dense in L6 and L7, that is, in the respective segments of entry. Labeled afferent fibers from both nerves projected rostrally at least as far as L1 and caudally as far as S2. Labeled fibers were found in Lissauer's tract as well as in the dorsal column immediately adjacent to the dorsal horn. In the spinal gray matter, both nerves had two main projection fields, one in the cap of the dorsal horn in lamina I, the other in the deep dorsal horn in laminae V-VI and the dorsal part of lamina VII. Both nerves, but particularly the PAN, projected to the medial portion of Clarke's column. No projection was found to laminae II, III, and IV of the dorsal horn or to the ventral horn. Since these findings parallel observations on hindlimb muscle afferent fibers, the present data support the existence of a common pattern for the central distribution of deep somatic afferent fibers.

Afferent Pathways↗

PubMed1988

Morphological characteristics of the innervation of the cat's knee joint.

The peripheral and central terminals of primary afferents of the cat's knee joint were studied with light- and electron microscopy (including HRP-transport methods). The majority of these afferent fibres are unmyelinated or thinly myelinated. In the periphery, they terminate in non-corpuscular endings. A dense network of branching nerve fibres surround the blood vessels to terminate at the vessel walls or in the adjacent dense collagenous tissue. Besides the terminals the fibres show preterminal bulges which are assumed to represent additional transduction sites. This implies that the whole distal fibre portion has a receptive function. The spinal projection is located in lamina I and V-VII of the dorsal horn. This location parallels that of muscular and visceral fibres, pointing to the possibility of a common projection pattern for deep somatic afferent fibres in the spinal cord of the cat.

Animals↗

PubMed1988

Fiber size distribution of myelinated and unmyelinated axons in the medial and posterior articular nerves of the cat's knee joint.

The distribution of fiber size in the posterior articular nerve (PAN) and medial articular nerve (MAN) of the cat's knee joint was studied by light and electron microscopy. The myelinated fibers of the PAN ranged from approximately 1 to 18 micron, with maxima at 3-4 micron and 8-9 micron. According to the classification of Boyd and Davey (1968), the PAN contained about 34% Group III fibers, 56% Group II fibers, and 10% Group I fibers. In contrast, the MAN showed a unimodal, skewed distribution, with a range from approximately 1 to 14 micron and a maximum at 3-4 micron. According to the Boyd and Davey classification, the PAN contained about 69% Group III fibers, 30% Group II fibers, and 1% Group I fibers. Unmyelinated fibers examined in the MAN showed a unimodal distribution, with a range of from 0.1 to 1.5 micron and a maximum at 0.4-0.5 micron. To differentiate between afferent and sympathetic fibers, a sympathectomy or ganglionectomy was performed on one side. The fiber size distribution indicated a considerable overlap in the diameter of the afferent and sympathetic unmyelinated fibers. Most sympathetic fibers had a diameter of between 0.8 and 0.9 micron, whereas afferent fibers showed a maximum at 0.3-0.4 micron. When data were combined for myelinated and unmyelinated fibers in the PAN, about 74% of the afferent fibers were found to belong to Groups III and IV; they are thought to terminate in noncorpuscular endings. The other 26% were found to belong to Groups I and II; they terminate in corpuscular receptors and muscle spindle primary and secondary endings.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Effects of acetylsalicylic acid and indomethacin on single groups III and IV sensory units from acutely inflamed joints.

In cats with an acute experimental inflammation in the right knee joint the effects of acetylsalicylic acid (ASA) and indomethacin on the discharge properties of single fine myelinated and unmyelinated articular afferent units were tested. The knee joint was inflamed by injection of kaolin and carrageenan into the joint cavity some hours before the recording period. Before drug application the single afferent fibres showed resting activity and responses to movements of the joint within its working range which is common for units from the inflamed knee. Resting activity was reduced significantly in most units within 0.5 h after the intravenous injection of the drugs. Within the observation time of about 1-2 h there was no recovery. In a few units a transient increase of resting activity was observed immediately after the injection of a drug. After the initial observation period of 1-2 h the responses to movements were tested. They were reduced in all units except one myelinated afferent. Also during this testing period the resting discharges did not recover. Intra-arterial injection of prostaglandin E2 in low doses close to the joint temporarily nullified the depressing effects of aspirin and indomethacin. Resting activity and movement evoked responses were increased up to the level before the treatment with analgesic drugs. The effects of prostaglandin E2 lasted for several minutes to more than 1 h. The depression of resting and evoked activity in single afferent articular units from inflamed joints is discussed in relation to the analgesic properties of aspirin and indomethacin.

Afferent Pathways↗

PubMed1983

Histochemical localization of neuraminidase in the CNS of mice and fish by means of 5-brom-3-indolyl-alpha-ketoside of 5-N-acetyl-D-neuraminic acid (BI-NeuAc).

The applicability of the 5-brom-3-indolyl-alpha-ketoside of N-acetyl-D-neuraminic acid (BI-NeuAc) as substrate for the histochemical indication of neuraminidase (GOSSRAU et al. 1977) was examined in frozen sections of brain, small intestine and kidney from suckling and adult mice and respectively from a cichlid fish (Sarotherodon mosambicus) with and without formaldehyde fixation. Following biochemical investigations using tritiated gangliosides as substrate a decrease in the activity of neuraminidase took place from about 50 to 80% after tissue fixation with formaldehyde. Nevertheless significant histochemical reactions were found only in fixed tissue sections. The specificity of this reaction was shown by means of inhibitions tests using 2,3-dehydro-2-desoxy-N-acetyl-neuraminic acid according to KUMAR et al. (1981). In contrast to distinct staining of neuraminidase activity in the small intestine and kidney, only faint reactions occurred in brain sections. From this it is concluded that the application of the new synthetic substrate for quantitative staining of neuraminidase seems to be not very suitable for the CNS.

Animals↗

PubMed1981

[Histochemical demonstration of sialic acid-containing compounds in the CNS of mice and goldfish by means of the mPAT ("mild" periodic acid-thionine)-method (author's transl)].

The "mild" periodic acid-thionine (mPAT)-method was examined for the quantitative research of histochemical localization of sialic acid (NeuAc)-containing compounds in brain samples of goldfish and albino mice in comparison to salivary gland (Glandula submandibularis) of the mouse. Biochemical determinations of NeuAc contents of the tissues showed that during histological treatment a significant decrease in the amount of lipid-bound NeuAc, especially in the brain had occurred, because of its high content of lipid-bound NeuAc. A previous KOH-treatment caused in an increase of the colour reaction, which indicated mainly the amount of O-acylated NeuAc just as possibly lactone containing NeuAc-compounds. The intensity of staining, especially in the optic tectum of goldfish, decreased to 45% after neuraminidase-treatment. The low concentration of NeuAc-compounds in the brain in comparison to the salivary glands, results in only a faint staining. Therefore, the use of the mPAT-method seems to be not very suitable for a specific and quantitative staining of all NeuAc-compounds in the CNS.

Animals↗