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Parallel collagen fibers such as ligaments and tendons are composed of fiber bundles, or fascicles, enclosed in a sheath of reticular membrane. In the Achilles tendon, these fascicles can be long, extending from the gastro-soleus unit to the calcaneal insertion site (Fig. 1). Although the overall functional behavior of the whole tendon is well established[1], there is little information detailing properties of individual fascicles or their interactions. Knowledge of the structural and biomechanical properties at the “mesostructural” scale (i.e. fascicle-scale) is critical to understanding tissue pathologies; in particular the processes involved in injury and healing, and the development of improved computational models and functional tissue engineered constructs.Copyright © 2007 by ASME

The immunolocalization of three members of the S100 calcium-binding protein family was investigated in the dog cochlea during normal postnatal development. Sections of decalcified and paraffin-embedded cochleae from 16 beagle puppies aged from birth to 3 months were treated with polyclonal antisera raised against the human recombinant S100A1, S100A5, and S100A6 proteins. At birth, in the dog cochlea, S100A1 was expressed in the immature Deiter's cells, and slightly in the pillar cells. From the second week, S100A1 was detected in the supporting structures of the organ of Corti, i.e. the Deiter's, the pillar, the border, and the Hensen's cells, and in the reticular membrane. From birth onwards, S100A5 remained a neuronal-specific protein, only located in a subpopulation of neurons in the spiral ganglion. S100A6 was not expressed at birth. From the second week of life, the Schwann cells and nerve sheaths in the modiolus, in the spiral ganglion, and running in the direction of the organ of Corti exhibited S100A6-labeling. From the 12th postnatal day, some scattered intermediate cells started to express S100A6 protein in the stria vascularis. The number of labeled intermediate cells increased during the third week. At adult stage, the intermediate cells were S100A6-stained with cytoplasmic labeling throughout the stria vascularis from the base to the apex of the cochlea. None of the other cochlear structures expressed the S100 proteins under study during the postnatal development of the dog cochlea. The S100A1, S100A5, S100A6 immunostaining was limited to specific cell types in dog cochlea. These S100 proteins were useful markers in the study of supporting cells, neurons, nerve fibers sheaths and stria vascularis (S100A6) during the normal postnatal development of the dog cochlea.

Bell and Fletcher [J. Acoust. Soc. Am. 116, 1016-1024 (2004)] proposed that one of the functions of activity of the outer hair cells (OHCs) might be a fluid-pumping action generating lateral fluid flow in the gap between the reticular membrane and the tectorial membrane and they supplied mathematical and descriptive justification for their theory which drew heavily upon the postulation (Gold, 1948) of the need for an active mechanism in the mammalian cochlea. In the 1970s there had been considerable speculation about how the inner hair cell (IHC) stereocilia are stimulated, whether they are stimulated in proportion to basilar membrane displacement or velocity or both, and whether the velocity dependence is due to subtectorial fluid flow. In 1977 experiments were conducted to investigate the possibility of subtectorial fluid flows using a dye as tracer. The work was not reported because it had been conducted at a time when visual observation of cochlear function had fallen out of favor in comparison with the more sensitive techniques thought necessary to observe submicroscopic phenomena, and secondly because it yielded a negative result. The essential details of those experiments are reported here to note for the record the extent to which this elaborate idea has already been tested.

The reticular membrane is composed of the brush border of hair cells and the tops of their supporting apparatus. The receptor membrane is considered to have a polarizing property since the phase of cochlear microphonics (CM) is reversed in electrode penetration from one side of the reticular membrane to the other and also the amplitude of CM is increased or decreased by appling current through the membrane.The sensory hairs of hair cells face to an environment of high potassium and very low calcium concentrations. This characteristic ionic environment is necessary to the maintenance of the CM sensitivity. The role of calcium ions in the initial receptive process of hair cells is discussed.

The cochleae of 5, 10, 12 and 15 day old mice and of adults (Mus musculus, strain NMRI) were studied by light and electron microscopy. In each case the same part of the organ of Corti (2.8-3.3 mm from the helicotrema) was examined. The results were correlated with the development of auditory thresholds (in mice of the same strain) obtained by Ehret (Ehret, G. (1971) J. Am. Audiol. Soc. 1, 179-184). It was demonstrated that morphological development of the organ of Corti is by no means complete at the onset of behavioural responses to acoustic stimuli. After this event the following morphological changes occur: (1) The basilar membrane filaments stain more intensely and the tympanic cover layer is greatly reduced in thickness and almost completely disappears. (2) The filaments of the pillar cells stain more intensely and apparently increase in number, and the angle between the outer and inner pillar cells increases so that the cross-sectional area of the tunnel of Corti expands. (3) Hook-shaped connections (marginal pillars) between the reticular membrane and the tectorial membrane disappear. The consequences of these morphological changes for the cochlear mechanics are discussed, especially in respect to the increase of sensitivity of hearing.

Sarcoplasmic reticular vesicles were prepared from both lobster and rabbit muscle. A variety of water-soluble, lipid-soluble, and alkylating spin labels were used to treat the sarcoplasmic reticular vesicles. All spin label analyses were carried out with and without NiCl 2 . Nickel is used to remove spin label signal originating from outside of, on the surface of, or localized in the outermost part of the outer bilayer half of the sarcoplasmic reticular membrane. We conclude that the hydrocarbon portion of sarcoplasmic reticular vesicles has symmetry in regard to the physical properties that limit spin label motion; however, we find that the membrane interface limits spin label motion more on the inner surface than the outer surface and that the trapped aqueous volume which is sampled by water soluble spin labels inside the vesicle enclosure limits spin label motion much more than the average aqueous medium outside.

The junctional complexes in the reticular membrane of the organ of Corti have been investigated in chinchilla inner ear by the freeze-fracture method. Extremely developed zonulae occludentes were observed where the supporting cells contact each other and the sensory cells. These junctions can be considered “very tight” and completely seal off the tunnel of Corti, Nuel's space and the outer tunnel from the endolymph, as observed by investigations carried out by using tracers. The zonulae occludentes between Hensen's cells are always uninterrupted but considerably lower than among supporting and sensory cells.

✓ In a study of the cavernous sinus in 70 specimens, the lateral wall of the sinus was found to be formed by two layers: a superficial, dural layer and a deep layer. The latter was formed by the sheaths of nerves III, IV, and V1,2 plus a reticular membrane extending between the sheaths. This membrane was often incomplete, particularly beween the sheaths of nerves III and IV above, and V1 below. These findings do not conform with the descriptions of a single dural layer of the lateral wall, with nerves III, IV, and V1,2 embedded in it, nor to other descriptions showing the cavity of the sinus divided into two compartments by a septum close to the lateral wall, with nerves III, IV, and V1 located within the septum. In the present study, the superficial and the deep layers of the lateral wall were found to be loosely attached to each other and easy to separate. In no case was a superficial compartment of the sinus found to be present between the two layers, and the nerves were never found to be running embedded in the superficial layer.

Electron microscopic study of the cochleas of an individual with bilateral Ménière's disease revealed the presence of many abnormal sensory cells in the apical regions of the cochleas. The pathological alterations were greater in the left ear with the greater hearing loss. There were some giant cilia, fusion of cilia, and loss of cilia. The outer hair cells contained diffuse cuticular bodies near or basal to the nuclei. Many outer hair cells were retracted away from the reticular membrane. The population of the nerve endings appeared normal. The inner hair cells of the apical turns appeared essentially normal. The spiral ganglia were normal in number and morphology at the apical turns, and a majority of their cell bodies were of the unmyelinated or partly myelinated types. The stria vascularis showed atrophy; however, the magnitude of this change was consistent with that known to occur in the aging ear. In the distended areas Reissner's membrane showed areas devoid of mesothelial cells, as well as atrophic epithelial cells. The blood vessels were no different from other human cochlear vessels. These abnormalities seen in the stereocilia, the outer hair cells, and Reissner's membrane are a matter of fact. We must admit, however, that not enough electron microscopic studies have been performed on ears from aging individuals or ears with other pathologies to state that these changes are unique to Ménière's disease. Furthermore, there is currently insufficient knowledge to predict whether these changes affect auditory function.

Investigations were performed by light microscope on the surface areas of the tympanal wall of the ductus cochlearis of the guinea pig, rabbit, cat and dog. Dissected specimens of the cochlea after silver reaction were used. This staining method was very helpful in observing the structure with fine high contrast.When Huschke's teeth of the spiral limbs are viewed from above, they run from the modiolus toward the inner sulcus cells with many interposed bridges between them. The surface extensions of the interdental cells (superficial cells of the spiral limbs) make a radial mosaic pavement as a whole in the direction from the modiolus toward the inner sulcus cells with slightly increasing surface area.The free surface of the inner sulcus cell becomes smaller toward the inner supporting cells.The reticular membrane maintains its compact structure in cases in which outer or inner hair cells have failed to develop. The pattern of repair of the reticular membrane was shown.At the border between Hensen's and Cl...

1. The integrity of the reticular membrane was maintained even after the outer hair cell loss. Some patterns of the replacement structure of the reticular membrane were demonstrated. 2. The inner sulcus, the Boettcher’s or Gladius’ cells replaced the organ of Corti after its complete destruction. 3. The invasion of endolymph into the space of cortilymph was discussed for reason of a possible additional cause for the degeneration of the sensory and supporting cells of the organ of Corti.

A short historical introduction is followed by a description of the technique for observing the organ of Corti in a lightly anesthetized guinea pig with the help of a slit lamp. The magnification was around 200 times, and stroboscopic illumination was used with a 1‐kilowatt high pressure mercury‐arc lamp. The relative stiffness of the Reissner's membrane, the tectorial membrane, the reticular membrane, and the Hensen cells were investigated with test needles. It was possible to demonstrate the earlier anatomical concepts of the stiffness of the reticular membrane and the pillars of Corti.In order to obtain the high sensitivity of the ear, the stiff tissues of the organ of Corti must be mechanically matched (impedance matched) to vibrating energy. of the perilymph. It was found that the organ of Corti is very well suited to work as a transformer for shearing forces.The difference between the vibration pattern of a series of resonators in the sense described by Helmholtz and the pattern of traveling waves i...

A method has been developed by which the separation of plasma membrane fragments from those of the smooth and rough endoplasmic reticulum of Ehrlich ascites tumor could be achieved. The fractions were characterized by enzyme constituents, carbohydrate contents, physicochemical measurements, and electron microscopy.

Triphosphoinositide (TPI), an aminoglycoside receptor and a possible regulator of cationic permeation through its ability to bind with Ca++, was localized by the protein-A gold technique in vestibular sensory epithelia using an antibody highly specific to TPI. TPI was detected on the stereocilia, kinocilia, and cuticular plate of hair cells, and in the reticular membrane of supporting cells. The cilia of hair cells are damaged by aminoglycosides at a relatively early stage of toxicity. Ca++-regulated bioactivity in this area is probably involved.

We studied the distribution of wheat germ agglutinin (WGA)-bindable glycoconjugates in the vestibular ampulla of mongolian gerbils. WGA was conjugated with gold particles and applied to Lowicryl K4M sections of the ampulla. WGA-binding sites were found on the cupula and some of the secretory granules and Golgi apparatuses in the supporting cells of the sensory epithelia. The granules were seen to secrete into the endolymphatic space through reticular membrane. It is likely, therefore, that glycoconjugates are glycosylated at the Golgi apparatus in the supporting cells, stored in the granules, and secreted through the reticular membrane into the endolymphatic space to be used as a component of the cupula. The cell membranes of various cells, connective tissue filaments in the perilymphatic space and the cytoplasm of melanocytes were also labeled with WGA-gold.

The concept of endoplasmic reticulum (ER) was introduced by electron mi-croscopists to designate a well-developed system of reticular membrane occurring in the internal regions of most cells. This specific intracellular membranous system is particularly important in neurons, where it forms a complex network of intraneuronal channels isolated from the surrounding neuroplasm. Three main components have generally been attributed to this intracellular membranous compartment: the rough endoplasmic reticulum (RER), the Golgi apparatus, and the smooth endoplasmic reticulum (SER). The particular aspect of the neuronal ER results from its highly regionalized organization: whereas the RER and Golgi complexes are rigorously confined to the perikarya and the proximal part of the dendrites, the SER is present in all neuronal sections, especially all along the dendritic and axonal processes, which may extend over distances thousands of times greater than the cell body diameter.

Precipitation of cobalt ions and iontophoretic marking by Alcian Blue were utilized in examination of physiological properties of the subtectorial space in the guinea pig cochlea. Cobalt ions injected into the scala media were sulfurated and observed as a black precipitation in cross sections. Precipitation was seen on the upper and the lower surface of the tectorial membrane, and on the reticular membrane. Alcian Blue was the most suitable dye for marking in the organ of Corti. Recording sites of potentials in the subtectorial space were identified by Alcian Blue marking. The potentials were similar to those measured in the scala media. These facts verify that the subtectorial space communicates with the scala media through the outermost margin of the tectorial membrane. Thus the sensory hairs of hair cells are bathed in the endolymph of high potassium concentration, and the condition for optimum sensitivity of their receptor function is maintained.

The vestibular sensory epithelia are situated on the macula sacculi, the macula utriculi and the three cristac ampullares. Already the early authors (Scarpa, 1789; Steifensand, 1835) were able to follow the nerve fibres to these regions, but Schultze (1858) was the first to give a description of the structure of the sensory epithelium. He described in elasmobr.tinchs three different types of cells, and also observed sensory hairs projecting from the surface of the epithelium. Odenins (1867) made similar findings in man. In the sane year, however, Hasse showed in birds (Hasse, 1867a), and in dogs and cats (liasse. 1967 b) that the sensory epithelium on the cristae and the macula utriculi contained only two different cell types, which, according to his description. correspond to the now recognized sensory cells (hair cells) and supporting cells. The nerve fibres made contact with the sensory cells, and it was also from these cells that the hairs projected. Retzius (1871) found that each sensory hair was not homogenous, but consisted of a number of very fine threads of different lengths. By analogy with previous findings in the organ of Corti, Pritchard (1876) described an increased density of the uppermost structures of the sensory epithelium, and he called this the reticular membrane. After systematic studies (Reteins (1881a, 1884) found that the basic features of the structure of the vestibular sensory epithelia were uniform in all vertebrates. Van der Stricht. (1908) and Held (1909) later showed that the sensory hairs were not all of the same type, as previously believed. but could be differentiated into true sensory hairs and a flagellum.

Rapid loss of cochlear microphonics in guinea-pigs previously exposed to high-energy impulse noise was shown to be related to the breakdown of the endolymphatic boundary. The cochlear duct was rendered leaky by deterioration of the reticular membrane, and damage of sensory and supporting cells.

It is well known that the width of the basilar membrane is narrower in the basal turn than in the apical turn, and the width and thickness of the tectorial membrane follow the pattern of the basilar membrane. The size of the organ of Corti and angle of slope of the reticular membrane in relation to the basilar membrane are larger in the apex than in the basal turn. Ciliary height of the sensory cells also gradually varies from apex to base. Inner hair cell cilia are uniformly taller than the first row of outer hair cell cilia. In the apex and midturn the cilia of the third row of outer hair cells are tallest, but in the basal turn the inner hair cell cilia are tallest (twice as tall as the outer hair cell cilia), as shown in Table I. The possible implications of the mechanical coupling of sensory cilia to the tectorial membrane are discussed. [Work supported by U.S.A.F. and The Deafness Research Foundation.]

The membranous labyrinth of normal guinea pig was studied by the electron microscope, and the following several findings were reported1. Shape and internal structures of hairs. Relationship of hairs to cuticula and tectorial membr-ane.2. Smooth and rough surfaced endoplasmic reticulum, and arrangement of mitochondria within external and internal hair cells.3. Fine structures of supporting cells, reticular membrane, Hensen's cell, tectorial membrane crista spirale, basilar membrane and mesothelial cell.4. Postmortal changes of hair cells and supporting cells of the organ of corti.5. Innervation and internal structure of the peripheral fibers of acoustic nerve.6. Difference of shape and internal structures of nerve end organ at the external and internal hair cells.7. Flow of the nutritional material within the organ of corti.