Über das Endgebiet des Perineuriums an den Zahnnerven der Ratte

Zusammenfassung Das Perineurium der Zahnnerven endet offen in Form einer Übergangszone. Diese Zone beginnt bei den einzelnen Faszikeln in verschiedener Höhe im subalveolären Knochenmark oder im Periodontium und ist charakterisiert durch den Schwund der Basalmembranen. Im Gegensatz zu anderen Endgebieten wird an den Zahnnerven zunächst die Basalmembran zum Epineurium lückenhaft, während sie auf der endoneuralen Seite noch weiter besteht. Schließlich umgibt nur noch eine von Basalmembranen freie, geschlossene Zellhülle die Faszikel. Hier ist eine Unterscheidung von Perineuralzellen und Fibroblasten nicht mehr möglich. Mit Eintritt in die Pulpa oder kurz danach endet diese Zellscheide bei allen Faszikeln in gleicher Weise nicht wie ein offenes Rohr, sondern unter allmählichem Verlust der Zellkontakte. Die Zellen liegen isoliert und nur noch in loser Beziehung zu den Nervenfaszikeln.Den Nerven im subalveolären Knochenmark und dem Periodontium fehlt ein regelrechtes Epineurium. Hier ist lediglich eine flache, nur selten kontinuierlich um den Faszikel ausgebildete Schicht von Kollagenfibrillen ausgebildet, die mit einem Kaliber von 60–120 m teils größer, teils gleich groß wie im Endoneurium sind. Mikrofibrillen liegen gelegentlich vereinzelt oder bündelweise dazwischen.

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On the terminal of the perineurium of the rats dental nerves

Summary The perineurium of the dental nerves is open-ended and terminates by forming a zone of transition. The beginning of this zone varies in height for each of the fasciculi within the subalveolar marrow or the periodontium. It is characterized by the loss of basement membranes. In contrast with the perineurium-endings of other nerves, in dental nerves the basement membrane becomes interrupted on the outer surface at first but keeps on covering the inner surface. Finally the fasciculi are enclosed by a cellular sheath lacking basement membranes, thus making it impossible to differentiate between perineural cells and fibroblasts. Where the nerves enter the pulp or just above this point this cellular sheath terminates in an equal manner for all fasciculi, not like an open sleeve but by successive loss of cellcontacts. The cells become isolated from each other laying in loose relation to the nerve fasciculi.Within the subalveolar marrow and the periodontium the nerves lack a proper epineurium. The envelope consists only of a thin layer of collagen fibrils which is seldom complete around the fasciculi. These fibrils measure 60 to 120 m. in diameter thus being partly of a larger and partly of the same calibre as the ones in the endoneurium. Occasionally individual or bunches of microfibrils occur among them.

Die Untersuchungen wurden im elektronenmikroskopischen Laboratorium bei Herrn Priv.-Doz. Dr. J. M. Schröder durchgeführt. Ihm und den Technischen Assistentinnen Fräulein Eckstein, Fräulein Frenk und Frau Schilling möchte ich für Hilfe Dank sagen.     

Regulatory peptides in the pancreas of two species of elasmobranchs and in the Brockmann bodies of four teleost species

Summary Immunohistochemistry was used to localize regulatory peptides in endocrine cells and nerve fibres in the pancreas of two species of elasmobranchs (starry ray,Raja radiata and spiny dogfish,Squalus acanthias), and in the Brockmann bodies of four teleost species (goldfish,Carassius auratus, brown troutSalmo trutta, rainbow trout,Oncorhynchus mykiss and cod,Gadus morhua). In the elasmobranchs, the classical pancreatic hormones somatostatin, glucagon and insulin were present in endocrine cells of the islets. In addition, endocrine cells were labelled with antisera to enkephalins, FMRF-amide, gastrin/cholecystokinin-(CCK)/caerulein, neurotensin, neuropeptide Y (NPY), and peptide YY (PYY). Nerve fibres were demonstrated with antisera against bombesin, galanin and vasoactive intestinal polypeptide (VIP). These nerve fibres innervated the walls of blood vessels, in the exocrine as well as the endocrine tissue. In the four teleost species immunoreactivity to somatostatin, insulin and glucagon was intense in the Brockmann bodies. Cells were labelled with antisera to enkephalin, neurotensin, FMRFamide, gastrin/CCK/ caerulein, NPY, PYY and VIP. Only a few nerve fibres were found with antisera against dopamine--hydroxylase (DBH, cod), enkephalin (met-enkephalin-Arg-Phe, cod), bombesin (cod), gastrin/CCK/caerulein (cod) and VIP. Galanin-like-immunoreactive fibres were numerous in the Brockmann bodies of all teleosts examined. Immunoreactivity to calcitonin gene-related peptide (CGRP), substance P, tyrosine hydroxylase (TH), and phenyl-N-methyl transferase (PNMT) could not be found in any of the species studied.     

Organization of rat mesenteric artery after removal of cells or extracellular matrix components

Summary Rat mesenteric arteries, perfusion fixed in relaxed or contracted conditions, were digested with acid and elastase, bleach (sodium hypochlorite), or alkali to selectively remove collagen, elastin, or cells. Scanning electron microscopy was used to study the three-dimensional organization of the remaining cells or extracellular components. Smooth muscle cells of the tunica media were elongated and circumferentially oriented. Superior mesenteric artery cells had an irregular surface with numerous projections and some ends were forked. Small mesenteric artery cells were spindle shaped with longitudinal surface ridges, and showed extensive corrugations upon contraction. Elastin was present both as laminae and as an interconnected fibrous meshwork. Collagen was arranged in an irregular network of individual fibrils and small bundles of fibrils that formed nests around the cells in both arteries. This irregular arrangement persisted, with no apparent reordering or loss of order, upon contraction. The lack of an ordered arrangement or specialized organization at the cell ends suggests mechanical coupling of the cells to elastin or collagen throughout the length of the cell, allowing for force transmission in a number of directions. The tunica media is thus a composite material consisting of cells, elastin, and collagen. The isotropic network of fibers is well suited for transmitting the shearing forces placed on it by contraction of smooth muscle cells and by pressure-induced loading.     

Intraepidermal nerves in human digital skin

Summary Intraepidermal nerve fibers of human glabrous digital skin were investigated using a new silver impregnation method. Nerves were observed to enter the epidermis without regional preference, and to extend into the stratum granulosum. They are non-varicose (smooth) or varicose and range from less than 0.2 m to approximately 2 m in diameter, with varicosities up to 3 m in diameter. Some axons branch profusely within the epithelium, giving off fine branches of differing diameters, while others appear to remain unbranched. At least some intraepidermal axons are fine branches of larger axons taking a horizontal course below the epithelial layer. Others are, at least topically, closely associated with Meissner's corpuscles. At 57 nerves per mm² surface area, the density of intraepidermal nerves found in this investigation is much greater than that reported in recent publications, and agrees closely with values given in several older studies.Dedicated to Prof. Dr. A. Hopf on the occasion of his 65th birthday     

Catecholaminergic nerves in the embryonic chick ovary: co-localization with β2-adrenoceptor-bearing steroidogenic cells

Summary The present study investigates the innervation of the embryonic chick ovary with regard to (i) development and compartmentalization of catecholaminergic nerves, and (ii) presence of adrenoceptors on steroidogenic target cells of catecholaminergic nerve terminals. Catecholaminergic nerve fibers visualized by glyoxylic acid-induced histofluorescence first appeared at embryonic day (E) 13. From E15 through E21 the density of fluorescent aminergic nerves increased markedly in parallel with the concentration of catecholamines and numbers of nerve bundles and single axons seen at the electron-microscopic level. Catecholaminergic nerves were confined to the ovarian medulla and closely associated with interstitial cells. Nerve terminals approached interstitial cells up to a distance of 20 nm and, in their majority, exhibited uptake of the false adrenergic transmitter 5-hydroxydopamine. Although adrenaline amounted to 14% of the total catecholamine content at E21, adrenaline immunoreactivity was only detected in adrenal chromaffin cells, but not in nerve fibers or cell bodies within the ovary. Interstitial cells structurally matured between E15 and E21 as documented by an increase of smooth endoplasmic reticulum and tubular mitochondria. Monoclonal antibodies mAB 120 and BRK 2 raised against avian ₁ and mammalian ₂-adrenergic receptors revealed the presence of ₂-adrenoceptor-like immunoreactivity on the surface of interstitial cells, but not on any other cell type.The results are consistent with the notion of a dense adrenergic innervation of the embryonic chick ovarian medulla and its steroidogenic interstitial cells, and suggest the chick ovary as an excellent model for elucidating the functional role of a neural input to steroidogenic cells during development.     

Ultrastructure of the cirrus pouch of Cylindrotaenia hickmani (Jones, 1985) (Cestoda, Nematotaeniidae)

The cirrus pouch of Cylindrotaenia hickmani was examined by transmission electron microscopy. The cirrus pouch is a complex organ consisting of muscular, nervous and epithelial tissues. Muscles forming the cirrus pouch wall contain large myocytons that merge with myofibrils. Muscles supplying the gonadoducts within the pouch consist of small myocytons which are connected to associated myofibrils by elongate processes. Discrete neuromuscular junctions are commonly seen in both muscles. Two cells, thought to be neurons, are present in the pouch. The abundance of nervous tissue in the pouch is suggestive of a high level of neural control of the activity of that organ. The cirrus is lined by filamentous, hook-like and blade-like microtriches. Ciliated sensory receptors are found among the microtriches lining the cirrus. Epithelial cytons associated with proximal regions of the cirrus produce a material which is secreted from the syncytial cytoplasm of the cirrus. Intercellular junctions, resembling gap junctions, are common among the cells associated with the cirrus. The complexity of the cirrus pouch of C. hickmani suggests that this organ may prove valuable for studies on neuromuscular physiology and cellular interactions in cestodes.     

Substance P-immunoreactive sensory nerves in the lower respiratory tract of various mammals including man

Summary The occurrence and origin of substance P (SP)-immunoreactive (IR) nerves in the lower respiratory tract was studied by means of immunohistochemistry in the guinea-pig, rat, cat and man. In addition, biopsies from human material were also analysed by radioimmunoassay. SP-IR nerves were seen in four principal locations: 1) under or within the lining epithelium, 2) around blood vessels, 3) within the bronchial smooth muscle layer, and 4) around local tracheobronchial ganglion cells. Ligation experiments combined with capsaicin pretreatments indicated that all SP-IR nerves in the respiratory tract are sensory. The trachea seems to be mainly supplied by the vagal nerves, while intrapulmonary bronchi and blood vessels receive SP-IR nerves of both vagal and non-vagal (spinal) origin. SP-IR nerves were also found in the human bronchi with principally similar location as in the guinea-pig. The levels of SP-IR in the trachea and peripheral bronchi of man were about 3–4 pmol/g, which is in the same range as the content of corresponding tissues from the guinea-pig.In conclusion, the present experimental findings of SP-IR nerves in the lower respiratory tract in both experimental animals and man support the functional evidence for the importance of SP in the vagal and non-vagal (spinal) control of bronchial smooth muscle tone and vascular permeability.     

Distribution and vasomotor effects of peptide HI (PHI) in feline cerebral blood vessels in vitro and in situ

Peptide HI (PHI)-immunoreactive nerve fibres were numerous around cerebral blood vessels of the cat. The number and distribution resemble that previously found for vasoactive intestinal polypeptide (VIP), a peptide with which PHI co-exists in pial arteries, at least in some segments. PHI and VIP elicit dilatation in a concentration-dependent manner in isolated middle cerebral arteries; the maximum effects were similar but VIP was considerably more potent. Neither effect was blocked by atropine, cimetidine or propranolol, confirming an action at a non-adrenergic, non-cholinergic site. In chloralose-anaesthetized cats PHI and VIP elicited concentration-dependent dilatations; the magnitude of responses was similar, however, considerably more PHI was necessary to elicit the same response as that of VIP. The results suggest that though both peptides are co-localized and may act at the same receptor, VIP is a more likely candidate for eliciting dilatation during physiological conditions.     

Axoplasmic flow of adrenaline and monoamine oxidase in amphibian sympathetic nerves

Summary The accumulation of both A and MAO proximal to a ligature on toad spinal nerves has been shown to occur at a slower rate than in mammals. As in mammals, there are two components of axonal transport in amphibian nerves, with the accumulation of A reaching a peak at between 4 and 7 days (cf. 2–4 days for NA in mammals), while MAO accumulation does not reach its maximum before 9 days (cf. 7 days in mammals). No accumulation occurs after sympathectomy, providing evidence for localization of MAO within amphibian sympathetic adrenergic nerves. Distal accumulation of MAO occurs in toad sympathetic nerves; this has not been reported to occur in mammalian nerves. Distal accumulation reaches a peak at 2–4 days, which suggests either a fast retrograde flow of MAO or that induction of MAO is occurring. These results are discussed in relation to differences between mammalian and amphibian sympathetic nerves and to the events occurring following ligation of these nerves.We wish to thank Judy Lenk, Vivienne Einhorn and Barbara Peachey for their assistance with the initial MAO histochemical work. This work was supported by grants from the National Heart Foundation of Australia and the Australian Research Grants Committee.     

Ultrastructural evidence for the presence of nerve cells in the gastrodermis of Hydra

Summary Two types of nerve cells, namely, neurosensory and neurosecretory cells have been identified and described in the gastrodermis of Hydra pseudoligactis. The morphological criteria used for the identification of gastrodermal nerves are based on those presented previously for epidermal nerves. The third type of nerve cell in the epidermis, ganglionic cells, was not observed in these studies. The distribution, function and origin of gastrodermal nerve cells are discussed briefly.With the technical assistance of Linda M. Bookman.