Monika von Düring

The ultrastructure of taste and touch receptors of the Frog's taste organ

SummaryThe taste buds from fungiform papillae and the hard palate of frogs were investigated with the scanning and transmission electron microscopes. An immature pre-taste cell and a mature taste cell can be differentiated. Only the mature taste cell exhibits synaptic contact with the afferent taste fibre. Glandular and satellite supporting cells envelop the thin apical processes of the sensory cells. At the base of the taste disc up to 10 Merkel cells form a complex with nerve endings. There are two types of myelinated fibres, large and small. The small fibre innervates the taste cells, the thicker nerve fibre the Merkel cells. The occurrence of two types of receptors explains physiological results.

Homozygous mutations in caveolin-3 cause a severe form of rippling muscle disease

Heterozygous missense mutations in the caveolin‐3 gene (CAV3) cause different muscle disorders. Most patients with CAV3 alterations present with rippling muscle disease (RMD) characterized by signs of increased muscle irritability without muscle weakness. In some patients, CAV3 mutations underlie the progressive limb‐girdle muscular dystrophy type 1C (LGMD1C). Here, we report two unrelated patients with novel homozygous mutations (L86P and A92T) in CAV3. Both presented with a more severe clinical phenotype than usually seen in RMD. Immunohistochemical and immunoblot analyses of muscle biopsies showed a strong reduction of caveolin‐3 in both homozygous RMD patients similar to the findings in heterozygous RMD. Electron microscopy studies showed a nearly complete absence of caveolae in the sarcolemma in all RMD patients analyzed. Additional plasma membrane irregularities (small plasmalemmal discontinuities, subsarcolemmal vacuoles, abnormal papillary projections) were more pronounced in homozygous than in heterozygous RMD patients. A stronger activation of nitric oxide synthase was observed in both homozygous patients compared with heterozygous RMD. Like in LGMD1C, dysferlin immunoreactivity is reduced in RMD but more pronounced in homozygous as compared with heterozygous RMD. Thus, we further extend the phenotypic variability of muscle caveolinopathies by identification of a severe form of RMD associated with homozygous CAV3 mutations. Ann Neurol 2003

The fine structure of the inner ear in caiman crocodilus

SummaryThe auditory organ in young Caimans (50 to 80 cms length) was studied with SEM and TEM. The auditory organ contains the basilar membrane with the papilla basilaris and the 3 internal ear cavities. A “fourth cavity” bordering on the scala tympani extends into the medial fibrocartilaginous plate. It contains the first nodal region of the myelinated afferent nerve fibres. The efferent nerve fibres occurring in this portion are not myelinated. The sensory cells may be divided into the inner and outer hair cells. The inner hair cells are medially positioned on the basilar membrane above the “fourth cavity”. They are of a high prismatic shape and have relatively long stereocilia. The quantity of the inner hair cells increases from the region near the window towards the lagena. The outer hair cells are calotte shaped and, for this reason, have a relatively large free surface. For the most part, they lie on the tympanic portion of the basilar membrane. The stereocilia of the outer hair cells are remarkably short in contrast to those of the inner hair cells. Seen as a whole, the length of the stereocilia of both types increases from the region near the window towards the lagena. The afferent and efferent innervation of the inner and outer hair cells is on principle the same. In contrast to the outer hair cells, the inner hair cells have more synapses with afferent axons. The efferent axons form axosomatic and axodendritic synapses. Within the region of the tympanic portion of the basilar membrane, the efferent axons also form synaptic contacts with the supporting cells and hyaline cells.

Über die Feinstruktur der motorischen Endplatte von höheren Wirbeltieren

SummaryIn an electron microscopic study on glutaraldehyde perfused motor-endings of vertebrate striated muscles the morphology of different structures is described.The subneural apparatuses are not a characteristic feature with which to differentiate between slow and twitch muscle fibres. There are twitch fibre junctions with complete absence of any junctional folds of the muscle membrane.The arrangement of the structural elements in the motor ending is a very typical one. The synaptic vesicles lie in a differentiated axoplasm and are separated by several mitochondria from the endoplasmic reticulum, neurofibrils and neurotubules which are in direct connection. The synaptic vesicles seem to originate in tubules of the endoplasmic reticulum. They are often connected to one another by thin filaments. New formations of the endoplasmic reticulum are complex vesicles and brush bordered membrane differentiations. Complex vesicles are often to be seen at the presynaptic membrane. You can also find them rarely at the postsynaptic membrane and the Schwann-cell membrane. Mitochondria containing concentric cellular lamellae or expanded cristae and dense glycogen particles seem to express the normal alteration in the sense of a cell moulting. Glycogen particles are always to be seen in motor nerve endings. Sometimes they are scattered over nearly the whole axoplasm.The fine structure of motor endings is discussed in relation to the synthesis and resynthesis of the transmitter.ZusammenfassungDie Perfusionsfixierung mit Glutaraldehyd führt zu einer genaueren Darstellung der Strukturelemente in motorischen Endplatten höherer Wirbeltiere. Es wurden folgende elektronenmikroskopische Befunde erhoben:Der subsynaptische Faltenapparat ist kein sicheres Kriterium zur Unterscheidung einfach und multipel innervierter Muskelfasern, da die motorische Endplatte einfach innervierter Fasern ebenfalls faltenlos sein kann.Die Feinstruktur der motorischen Endplatte zeigt bei günstiger Schnittführung ein typisches Bauprinzip. Neurofilamente und Mikrotubuli des Axoplasmas sind in der Nähe des synaptischen Membrankomplexes mit dem endoplasmatischen Retikulum verbunden. Das Axoplasma geht in eine randständige Matrix über, in der die synaptischen Vesikel liegen. Das Chondriom bildet eine Grenzzone zwischen der Matrix und den einstrahlenden Axoplasmastrukturen. Die synaptischen Bläschen scheinen sich von Endoplasmaschläuchen abzuknospen. Sie sind über feine Stege miteinander verbunden. Besondere Membrandifferenzierungen an den Retikulumsohläuchen sind Stachelsaumcaveolen und Formationen mit bürstenartigem Stäbchenbesatz. Größere Stachelsaumbläschen treten an der präsynaptischen Membran auf, weniger häufig auch an dem postsynaptischen Sarkolemm und der Schwannzellmembran. Atypische Mitochondrienformen mit dichten lamellären oder lockeren bläschenreichen Formationen sind Ausdruck einer Degeneration, die im Zusammenhang mit einer Organellenmauserung auftreten könnte. Glycogengranula werden regelmäßig gefunden. In Sonderfällen füllen sie große Bereiche der motorischen Endplatte aus.Die Feinstruktur der motorischen Endplatte wird in bezug auf die Synthese und Resynthese der Transmittersubstanz diskutiert.

The anatomy and fine structure of the echidnaTachyglossus aculeatus snout with respect to its different trigeminal sensory receptors including the electroreceptors

SummaryThe gross anatomy and nerve supply of the bill of echidna (Tachyglossus aculeatus) is described in relation to its function as an outstanding sensory organ. The sensory innervation of the skin of the echidna snout was investigated by means of frontal serial sections, after decalcification of the specimens. A comprehensive light and electron microscopic description of the location and fine structure of cutaneous sensory receptors of the trigeminal system was made by this means. The encapsulated and non-encapsulated Ruffini receptors, the types of other free receptors in the connective tissue and the Merkel cell receptor do not differ morphologically from those of higher mammals, whereas the pacinian-like corpuscle shows a unique organization of its outer core. This is composed of large perineural cells containing a unique reticulum of parallel-orientated endoplasmic membranes. Lamellated corpuscles, seen in isolation or in association with push rods, are numerous in the snout and in the tip of the tongue of echidna. Push rod receptor organs occur in the hairless skin of the bill with a very dense array at its rostral end and in the pseudopalatal ridges. Gland duct receptors are restricted to the skin adjacent to the nostrils and the mouth opening, including the pseudopalatal plates. Only about one quarter of the total number of 400 seromucous glands receive a sensory innervation of their intraepidermal duct segment. Within each innervated gland two types of receptor terminals are identified.The distributions of the different receptor types are mapped for different regions of the skin, the mucous membrane of the nasal and oral vestibule and the tip of the tongue. The fine structure of nerve terminals is discussed from a comparative anatomical point of view, and some speculations are made about possible transduction processes that underlie the known electrophysiological properties. The sensory organs such as the “push rod” and “gland duct receptor”, and most of their sensory terminals, are less differentiated in echidna snout than in the platypus (Ornithorhynchus anatinus) bill.

The endolymphatic duct and sac of the rat: a histological, ultrastructural, and immunocytochemical investigation

A study of the ultrastructure, vascularization, and innervation of the endolymphatic duct and sac of the rat has been performed by means of light- and electron-microscopic and immunocytochemical methods. Two different types of epithelial cells have been identified: the ribosome-rich cell and the mitochondria-rich cell. These two cell types make up the epithelium of the complete endolymphatic duct and sac, although differences in their quantitative distribution exist. The morphology of the ribosome-rich cells varies between the different parts of the endolymphatic duct and sac; the morphology of the mitochondria-rich cells remains constant. According to the epithelial composition, vascularization, and structural organization of the lamina propria, both duct and sac are subdivided into three different parts. A graphic reconstruction of the vascular network supplying the endolymphatic duct and sac shows that the vascular pattern varies among the different parts. In addition, the capillaries of the duct are of the continuous type, whereas those supplying the sac are of the fenestrated type. Nerve fibers do not occur within the epithelium of the endolymphatic duct and sac. A few nerve fibers regularly occur in the subepithelial compartment close to the blood vessels; these fibers have been demonstrated in whole-mount preparations by the application of the neuronal marker protein gene product 9.5. Single beaded fibers immunoreactive to substance P and calcitonin-gene related peptide are observed within the same compartment. Dopamine-β-hydroxylase-immunoreactive axons are restricted to the walls of arterioles. Morphological differences between the different portions of the endolymphatic duct and sac are discussed with regard to possible roles in fluid absorption and immunocompetence.

Topography and Ultrastructure of Group III and IV Nerve Terminals of the Cat’s Gastrocnemius-Soleus Muscle

Topography, structure and values of muscle spindles and Golgi tendon organs within the gastrocnemius-soleus muscle of the cat are well documented (Swett et al., 1960; Chin et al., 1962; Boyd and Davey, 1968; Ariano et al., 1973). More than two thirds of thick myelinated nerve fibers in a muscle nerve innervate these proprioreceptors (Boyd and Davey, 1968; Boyd and Smith, 1984). There is much evidence that the receptor rich portion of the striated muscle is rich in oxidative muscle fibers (Gonyea and Ericson, 1978; Botterman et al., 1978; Richmond and Stuart, 1985). In physiological studies of slowly conducting fine afferent units (group III and group IV afferents) in the gastrocnemius-soleus muscle different receptor types are classified: 1. low threshold mechanoreceptors (LTM), 2. receptors that are stimulated by contraction only (ergoreceptors), 3. thermoreceptors and 4. receptors stimulated by ischemic contraction (nociceptors) (Mense and Stahnke, 1983; Kaufman et al., 1984; Mense and Meyer, 1985). Other investigators describe the thin-fiber receptors in the skeletal muscle as polymodal receptors responding to mechanical, chemical and thermal stimulation (Kumazawa and Mizumura, 1977; Kumazawa and Tadaki, 1983; Kumazawa et al., 1983). The functional significance of fine afferent fibers of skeletal muscle receptors for the control of cardiovascular reflexes has been reviewed by Mitchell and Schmidt (1983). Little is known about the morphology of these fine afferents.

Four new cases of stomatin-deficient hereditary stomatocytosis syndrome: association of the stomatin-deficient cryohydrocytosis variant with neurological dysfunction

This report concerns congenitally Na+–K+ leaky red cells of the ‘hereditary stomatocytosis’ class. Three new isolated cases and one new pedigree are described, and one previously reported case is expanded. In all cases, Western blotting of red cell membranes revealed a deficiency in the 32 kDa membrane protein, stomatin. All showed pronounced cation leaks at 37°C with markedly abnormal intracellular Na+ and K+ concentrations, like all other such stomatin‐deficient cases. Consistent with recent findings in two previously described British pedigrees, immunocytochemistry demonstrated that the deficiency of stomatin was not complete. On typical blood films, some red cells showed positive stomatin immunoreactivity, while most were negative, although in one case only a minority were negative. All platelets and neutrophils were stomatin positive. The cases differed markedly between themselves with regard to the temperature dependence of the passive leak to K+. Three showed a simple monotonic temperature dependence, while two showed a minimum at around 20–25°C, such that the cells were extremely leaky at 0°C, giving the phenotype known as ‘cryohydrocytosis’. These patients are the only two known cases of stomatin‐deficient cryohydrocytosis. Both showed a congenital syndrome of mental retardation, seizures, cataracts and massive hepatosplenomegaly, probably defining a new haemato‐neurological syndrome.

Salivary cortisol and psychological mechanisms in patients with acute versus chronic low back pain

This study was designed to explore whether the basal adrenocortical activity is related with pain-related coping, nonverbal pain behavior, depressive mood, and fatigue in patients with acute and chronic nonspecific low back pain. 19 patients with acute low back pain (ALBP) and 24 with chronic low back pain (CLBP) participated in the study. The adrenocortical activity was assessed through the cortisol awakening response. All participants provided five saliva samples (0, 15, 30, 45, and 60min after waking) on two consecutive days off work. Pain-related coping [fear-avoidance coping (FAC) and endurance coping (EC)], nonverbal pain behavior (NPB), depressive mood, and fatigue were assessed through questionnaires. Among ALPB patients, EC was negatively associated with the cortisol release, whereas fatigue was positively associated with it. Among CLBP patients, FAC, NPB, depressive mood, and fatigue were negatively associated with the cortisol awakening response, whereas EC tended to be positively associated with it. The results indicate that pain-related coping strategies which are expected to be successful appear to lower the adrenocortical activity among ALBP patients, whereas affective distress may enhance the level of cortisol in this group. Among CLBP patients, long-term maladaptive coping strategies might contribute to hypocortisolism.

Topography and immunocytochemical characterization of nerve fibers in the leptomeningeal compartments of the rat. A light- and electron-microscopical study

Abstract.The localization of peptidergic, catecholaminergic, and nitroxidergic nerve fibers in the ventral leptomeningeal connective tissue compartment was studied in whole-mount preparations and serial semithin and ultrathin sections. For immunocytochemistry, whole-mount preparations of the leptomeninges and ventral brain slices with the meninges were incubated as free-floating specimens with primary antibodies against protein gene product 9.5 (PGP 9.5), substance P (SP), calcitonin gene-related peptide (CGRP), dopamine beta-hydroxylase (DβH), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), and nitric oxide synthase (NOS) using the avidin-biotin-peroxidase method. Based on the regional differences of the connective tissue organization, the leptomeninx is subdivided into the pial, trabecular, and adventitial leptomeninx. The antibody PGP 9.5 stains all unmyelinated nerve fibers in the leptomeninx. Although the highest density of nerve fibers occurs in the adventitial leptomeninx, nerve fibers, and terminals are additionally present in the trabecular and pial leptomeninx. DβH-, NPY-, VIP- and NOS-immunoreactive (IR) nerve fibers occur exclusively in the adventitial leptomeninx forming neuromuscular junctions. CGRP- and SP-IR nerve fibers are localized in all three leptomeningeal compartments where they terminate close to the subarachnoid space (type 1) or within the connective tissue (type 2). Due to their morphological and immunocytochemical characterization a possible chemo-, mechano- or nociceptive function is discussed in the context of pathophysiological aspects.