Electron microscopic observations on the epiphysial sensory cells in lizards and the pineal sensory cell problem

1960 ◽  
Vol 51 (6) ◽  
pp. 735-747 ◽  
Author(s):  
Willem Steyn
Keyword(s):  
Sensory Cell ◽  
Sensory Cells ◽  
Cell Problem ◽  
Electron Microscopic

Auditory sensory cells in hawkmoths: identification, physiology and structure

1999 ◽  
Vol 202 (12) ◽  
pp. 1579-1587 ◽  
Author(s):  
M.C. Göpfert ◽  
L.T. Wasserthal
Keyword(s):  
Neuronal Activity ◽  
Sensory Cell ◽  
Sensory Organ ◽  
Sensory Cells ◽  
Chordotonal Organ ◽  
Auditory Function ◽  
Sensory Structure ◽  
Ultrasonic Stimulation ◽  
Afferent Response

The labral pilifers are thought to contain auditory sensory cells in hawkmoths of two distantly related subtribes, the Choerocampina and the Acherontiina. We identified and analysed these cells using neurophysiological and neuroanatomical techniques. In the death's head hawkmoth Acherontia atropos, we found that the labral nerve carries the auditory afferent responses of a single auditory unit. This unit responds to ultrasonic stimulation with minimum thresholds of 49–57 dB SPL around 25 kHz. Ablation experiments and analyses of the neuronal activity in different regions of the pilifer revealed that the auditory afferent response originates in the basal pilifer region. The sensory organ was identified as a chordotonal organ that attaches to the base of the pilifer. This organ is the only sensory structure in the basal pilifer region and consists of a single mononematic scolopidium and a single sensory cell. In Choerocampina, a homologous scolopidium was also found and is probably the only sensory structure of the pilifer that might serve an auditory function. Since a pilifer chordotonal organ with only a single scolopidium has also been detected in a non-hearing hawkmoth species, hearing in the distantly related choerocampine and acherontiine hawkmoths presumably evolved from a single proprioceptive mechanoreceptor cell that is present in all hawkmoths.

Ultrastructure of a sensillum associated with the pharynx of the cockroach Periplaneta americana

1996 ◽  
Vol 74 (11) ◽  
pp. 1999-2008
Author(s):  
R. Gary Chiang ◽  
K. G. Davey
Keyword(s):  
Electron Microscopy ◽  
Cell Body ◽  
Extracellular Space ◽  
Direct Contact ◽  
Periplaneta Americana ◽  
Sensory Cell ◽  
Sensory Cells ◽  
Osmotic Concentration ◽  
Sensory Cilia ◽  
Ultrathin Sections

A sensillum associated with the pharynx of the cockroach Periplaneta americana was examined in serial ultrathin sections using electron microscopy. This sensillum consisted of a group of 10–20 similar sensillar subunits. Each sensillar subunit possessed one 60- to 70-μm long dendritic sheath that made direct contact with the cuticle. The dendritic sheath enclosed 3–5 sensory cilia arising from 3–5 sensory cells located in a cluster approximately 30 μm proximal to the base of the sheath. Between the sensory cell body and the base of the sheath the dendrites were wrapped by the sheath-forming cell. Before entering the dendritic sheath itself, the dendrites crossed through an extracellular space, the ciliary sinus. No cuticular specializations, such as a well-defined sensory hair or pore, were observed. The structure of this sensillum suggests that it responds poorly to mechanical distortion of its surroundings. This characteristic supports the hypothesis that this sensillum measures the osmotic concentration of the ingested food.

Electron Microscopic study of inner ear of guinea pig with special reference to morphological changes in vestibular macula in hypercholesterolemia

1993 ◽  
Vol 51 ◽  
pp. 430-431
Author(s):  
Yan Qiao ◽  
Goro Asano ◽  
Izumi Kashiwado ◽  
Yasuo Hattori
Keyword(s):  
Guinea Pig ◽  
Inner Ear ◽  
Vascular Function ◽  
Lipid Droplets ◽  
Morphological Changes ◽  
Ultrastructural Changes ◽  
Sensory Cells ◽  
Vascular Changes ◽  
Electron Microscopic ◽  
Microscopic Techniques

Vertigo may be induced by various factors such as vascular changes including arteriosclerosis and hypercholesterolemia in the inner ear. In orter to clarify the mechanism of vertigo, the inner ear of guinea pig in hypercholesterolemia condition was investigated by electron microscopic techniques.The guinea pigs have served as experimental materials. They were divided into two groups: one received non-administration of cholesterol and the other received the administration of cholesterol. The vestibular macula in inner ear were observed at 1, 2 and 3 months after the administration of cholesterol and also vascular function was investigated by using horseradish peroxidase as tracer.Ultrastructural changes such as the depletion of microvilli on the cell surface and increased microvesicles were detected in the cytoplasm of sensory cell after cholesterol administration. After two months, lipid droplets were demonstrated in the cytoplasm, associated with intercellular edema. The cytoplasmic projection with vacuolization was demonstrated in the surface of sensory cells in the vestibular macula after three months of cholesterol administration.

Comparative electron microscopic investigation of the nuchal organs in Protodriloides, Protodrilus, and Saccocirrus (Annelida, Polychaeta)

1990 ◽  
Vol 68 (2) ◽  
pp. 325-338 ◽  
Author(s):  
Günter Purschke
Keyword(s):  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Retractor Muscle ◽  
Sensory Cells ◽  
Ciliated Cells ◽  
Electron Microscopic ◽  
Distal Process ◽  
Transmission Electron ◽  
Sensory Cilia ◽  
Nuchal Organs

The nuchal organs of the interstitial polychaetes Protodriloides chaetifer, Protodriloides symbioticus, Protodrilus ciliatus, Protodrilus adhaerens, Saccocirrus krusadensis, and Saccocirrus papillocercus were investigated by scanning and transmission electron microscopy. These organs vary from spherical to elongated ciliary brushes and usually lie in shallow pits. In P. symbioticus only a reduced nuchal organ exists, whereas the other species all have well-developed nuchal organs of similar structure consisting of ciliated supportive cells and bipolar primary sensory cells. The perikarya of the sensory cells form the nuchal ganglia, which lie behind the brain. Different retractor muscle cells are attached to the ciliated cells. The number of sensory cells varies from 4 to about 90 according to the size of the nuchal organs. Each sensory cell gives rise to a distal process (dendrite), and 4–25 processes at a time unite to form bundles that penetrate between the ciliated cells. Apically the dendrites terminate in small sensory bulbs, each bearing several microvilli and a modified cilium. The sensory cilia usually branch, lose their axonemes, and extend as microvillus-like structures into the olfactory chamber representing an extracellular space below the reduced cuticle. Specific microvillar processes of the ciliated cells form a dense cover above the cuticle which is only penetrated by the motile cilia of these cells. The ciliated cells are highly pinocytic. The nuchal organs of the species investigated show striking similarities to those of spionids.

scholarly journals Peptide immunoreactivity of unmyelinated primary afferent axons in rat lumbar dorsal roots.

1989 ◽  
Vol 37 (7) ◽  
pp. 1047-1052 ◽  
Author(s):  
D L McNeill ◽  
K N Westlund ◽  
R E Coggeshall
Keyword(s):  
Substance P ◽  
Dorsal Root ◽  
Sensory Cell ◽  
Experimental Manipulation ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Dorsal Roots ◽  
Sensory Axons ◽  
Calcitonin Gene

The present study demonstrates calcitonin gene-related peptide (CGRP), somatostatin (SOM), bombesin (BOM), and substance P (SP) at the electron microscopic level in lumbar dorsal root axons of normal rats. The highest percentages of labeled axons were for CGRP (14%) and then, in descending order, for SP (8.6%), SOM (6.8%), and BOM (3.1%). The labeled axons were exclusively unmyelinated for SP, SOM, and BOM, and predominantly unmyelinated for CGRP. These data are consistent with the data for labeled sensory cell bodies for these same compounds. We emphasize that these peptides were immunocytochemically visualized in the dorsal roots without experimental manipulation, such as colchicine or dorsal root ligation. Quantitative sampling of this type can be used to assay changes in response to physiological stimuli in numbers of sensory axons that contain identifiable concentrations of these peptides.

Characterization of the synaptic membranes in the central nervous system through electron microscopic immunocytochemistry of the botulinum toxin

1978 ◽  
Vol 36 (2) ◽  
pp. 592-593
Author(s):  
Botulinum Toxin ◽  
Nobutaka Iiirokawa ◽  
Masaru Kitamura
Keyword(s):  
Botulinum Toxin ◽  
Botulinum Toxin Type A ◽  
Freeze Fracture ◽  
Botulinum Toxin Type ◽  
Sensory Cells ◽  
Synaptic Membranes ◽  
Target Cells ◽  
Electron Microscopic ◽  
Electron Microscopic Immunocytochemistry ◽  
The Central Nervous System

Synapses are established between neurites of nerve cells and target cells (e. g. neurons, muscles, sensory cells). Synaptic membranes differentiate to show two main characteristics: one is for release of neurotransmitters and the other is for recognition of its partner during development. Many investigations have been undertaken to visualize the characteristics of the synaptic membranes by lectins, PTA staining and freeze fracture technique. The precise substantial nature of the synaptic membranes, however, has little been known till now. In the present study we intend to characterize synaptic membranes through electron microscopic immunocytochemistry of the botulinum toxin. The binding site of this neurotoxin is supposed to be specific gangliosides and it is well known that the toxin blocks the transmitter release at the neuromuscular junction and gangliosides may contribute much in neuronal recognition.The botulinum toxin type A cristalline toxin was supplied by Dr. E. J. Schantz(Wiseonsin Univ. ).

The fine structure of crustacean proprioceptors I. The chordotonal organs in the legs of the shore crab, Carcinus maenas

1962 ◽  
Vol 245 (725) ◽  
pp. 291-324 ◽  
Keyword(s):  
Fine Structure ◽  
Connective Tissue ◽  
Sensory Cell ◽  
Light And Electron Microscopy ◽  
Carcinus Maenas ◽  
Sensory Nerve ◽  
Shore Crab ◽  
Structural Basis ◽  
Sensory Cells ◽  
Axial Filament

In the walking legs of the shore crab, Carcinus maenas , is a series of chordotonal organs. Each organ consists of a strand of elastic connective tissue in which are embedded scolopidia. The anatomy and histology of the organs in the coxopodite-basipodite, meropodite-carpopodite, carpopodite-propodite and propodite-dactylopodite joints are described in detail, as seen by light and electron microscopy. The organs are hereafter referred to by the initial letters of the leg segments with which they are associated. The CB organ runs from a projection near the dorsal hinge of the coxa to the dorsal rim of the basipodite. MC1 runs from the side of the tendon of the ‘accessory flexor’ muscle to two attachments on the preaxial wall of the meropodite. MC2 runs from the adductor tendon to the preaxial wall of the carpopodite. CP1 runs from the productor tendon to two ventral attachments on the carpopodite. CP2 runs from the reductor tendon to the floor of the propodite. PD runs from the adductor tendon to the postaxial wall of the dactylopodite. The scolopidia have a tube distal to the scolopale, into which are inserted the ends of the distal processes of bipolar sensory nerve cells. The tube is an extracellular organ apparently formed by the cell that contains the scolopale as an intracellular organ. Each scolopidium has associated with it two sensory cells, whose cell bodies lie in, on or near the connective tissue strands. In CB the sensory cells of a pair are similar to one another (isodynal scolopidia); in the other organs the two cells are dissimilar in their fine structure (heterodynal scolopidia). The difference, in the heterodynal scolopidia, consists in the presence or absence of a part of the distal process, the ciliary segment, which has nine double peripheral filaments regularly spaced, and in the precise form of the distal end of the axial filament. In all scolopidia, the two distal processes of the sensory cells are separated by intrusions of the sheath cells or of the scolopale cell, except for an area near the base of the scolopale where their cell membranes are in apposition; this area is referred to as the ephapse. At the level of the base of the scolopale the distal processes each contain an axial filament, which shows transverse striations, and there are attachment plaques between the distal processes and the scolopale cell. Distal to this level, each sensory cell contains a centrosome. Distal to the centrosome, the distal processes, which cross the scolopale space to end in the tube, can be divided into the following regions: a ciliary segment (where it occurs), a paraciliary segment characterized by nine double peripheral filaments less regularly arranged than in the ciliary segment, and a terminal segment characterized by numerous single microtubules. It is suggested that in each scolopidium one sensory cell responds to extension of the strand, and one to its shortening. This might account for the unidirectional responses observed in the organs. No structural basis for the observed differentiation of the sensory cells into ‘position’ and ‘movement’ receptors could be found.

scholarly journals Let-7 miRNAs control auditory sensory progenitor behavior in the vertebrate inner ear

2019 ◽  
Author(s):  
Lale Evsen ◽  
Shuran Zhang ◽  
Angelika Doetzlhofer
Keyword(s):  
Protein Expression ◽  
Inner Ear ◽  
Sensory Cell ◽  
Basilar Papilla ◽  
State Transitions ◽  
Sensory Cells ◽  
Chromatin Remodeler ◽  
Self Renewal ◽  
Auditory Organ

ABSTRACTThe evolutionary conserved lethal-7 (let-7) family of microRNAs (miRNAs) is a well-known activator of terminal mitosis and differentiation. Surprisingly, we previously found that overexpression of let-7 miRNAs in the murine auditory organ accelerated the terminal mitosis of auditory sensory progenitors (pro-sensory cells) but failed to stimulate their differentiation into mechano-sensory hair cells (HCs). To further address the role of let-7 miRNAs in auditory sensory differentiation, we conducted gain and loss of function experiments in the developing chicken auditory organ, the basilar papilla (BP). Using a sponge approach, we show that the disruption of let-7 miRNA function in the developing BP delays pro-sensory cell exit and delays differentiation of auditory HCs, revealing that endogenous let-7 miRNAs limit pro-sensory cell self-renewal in the developing BP. However, consistent with the role of let-7 miRNAs in the murine auditory organ, let-7b overexpression in the developing BP delayed HC differentiation, suggesting that too low or too high let-7 miRNA levels disrupt HC differentiation. Furthermore, we provide evidence that the repressive role of let-7 miRNAs in HC differentiation may be due to its targeting of the chromatin remodeler CHD7. Mutation in the human CHD7 gene causes CHARGE syndrome, which amongst others is characterized by inner ear and hearing deficits. Using target prediction algorithms, we uncovered a highly predictive and evolutionary conserved let-7 binding site within the Chd7 transcript. Consistent with being a target of let-7 repression, we demonstrate that let-7b overexpression significantly reduced CHD7 protein expression in to the developing BP. Furthermore, utilizing an inducible let-7g transgenic mouse model, we show that let-7 miRNAs negatively regulate CHD7 protein expression in developing murine cochlear, retinal and brain tissue. CHD7 is dosage dependent and the here described regulation by let-7 miRNAs may be critical to fine tune CHD7 protein levels during sensory and neuronal development.SIGNIFICANCEThe evolutionary highly conserved let-7 miRNAs are essential for proper timing of cell state transitions during embryogenesis. Even though abundantly expressed in the vertebrate auditory organ, surprisingly little is known about their function in auditory sensory differentiation. Here, we demonstrate that endogenous let-7 miRNAs are essential for limiting auditory sensory progenitor (pro-sensory) cell self-renewal. Furthermore, we find that precocious let-7 miRNAs expression interferes with auditory hair cell differentiation and identify chromatin remodeler CHD7 as a potential target gene of let-7 repressive function in HC differentiation.

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