The petrosal of Omomys carteri and the evolution of the primate basicranium

The first omomyine petrosals, those of Omomys carteri, are described. Omomys probably had a tympanic bulla and canals for the intratympanic carotid circulation derived from the petrosal bone. The stapedial and promontory canals were complete, large and subequal. The posterior carotid foramen entered the bulla posteromedially. The intratympanic portion of the facial nerve was fully enclosed in bone, the stapedius fossa is extrabullar and the parotic fissure is patent. The mastoid was pneumatized from the epitympanic recess and a supracochlear cavity may have been present. The Omomys petrosals exhibit a generic omomyiform morphology, exhibiting no features that can be interpreted as autapomorphies and only one feature shared with adapiforms. The monophyly of Omomyiformes is based on other cranial characters, dental and postcranial characters assessed elsewhere. The similarity of the Shanghuang petrosal to the petrosals of omomyiforms, as well as the ambiguous evidence of its association, suggest that an omomyiform affinity for that petrosal cannot be ruled out.     

Identification of the motoneurons innervating the stapedius muscle in Gallus gallus: a horseradish peroxidase study

The location of the stapedial motoneurons in Gallus gallus was investigated by means of the retrograde transport of HRP, injected into the stapedius muscle. The labeled neurons are located in both the ventral and dorsal divisions of the VII nerve nucleus, in a lateral and ventral position respectively, facing the superior olivary nucleus. The neurons are distributed in two size classes. The functional implications of these findings are discussed, in relation both to the absence of the acoustic stapedial reflex in birds and to the functional properties of the stapedius muscle.     

Acoustic structure of vocalization and stapedius muscle activity during vocal development in chickens (Gallus gallus)

The link between stapedius muscle activity and acoustic structure of vocalization was analysed in cocks of age 20–30 to 90–100 days old. The results show that stapedius muscle activation depends on the acoustic structure of vocalization and changes during vocal development. This dependence was observed in spontaneous calls and in vocalizations elicited by stimulating the mesencephalic calling area. In 30-day-old cocks stapedius muscle EMG response is never associated with vocalizations with an acoustic energy content which is always distributed at frequencies higher than 2000 Hz. The coupling between vocalization and stapedius muscle activity begins later, when birds produce vocalizations with acoustic energy shifted towards lower frequencies. Overall, stapedius muscle activity is related to a bird's production of high amplitude low frequencies. These results support the hypothesis that the primary role of the stapedius muscle during normal vocal development is to dampen the amplitude of low frequency energy that reaches the cochlea during vocalization.     

Mechanisms controlling vocalization-evoked stapedius muscle activity in chickens (Gallus gallus)

Summary The mechanisms involved in the vocalization-evoked stapedius muscle contraction in the chicken (Gallus gallus) were studied. The stapedius muscle EMG response is constantly associated with vocalization elicited by electrically stimulating the mesencephalic calling area. Stimulation of discrete points within the mesencephalic calling area elicits stapedius muscle EMG activity at low stimulus intensities, but does not evoke vocalization. The stapedius muscle EMG response remains unchanged after exclusion of both the syringeal and vagal afferent inputs. It is concluded that stapedius muscle activity is not driven by a neural reflex originating within the syrinx, but is elicited by a central drive.EBS-elicited stapedius muscle activity, identical in all respects to that obtained in an intact preparation, is present when vocalization is prevented by synringeal muscle denervation and tracheal occlusion. This rules out the possibility that stapedius muscle activation could be due to vocalization-linked afferent impulses other than vagal and syringeal ones. Stimulation of discrete points within the mesencephalic calling area can elicit separately vocalization and stapedius muscle activity. This finding is discussed in terms of the existence of two midbrain neuronal populations, projecting to the XIIth nucleus (controlling the syrinx) and to the VIIth nucleus (controlling the stapedius).Abbreviations EBS electrical brain stimulation - EMG electromyogram - ICo nucleus intercollicularis - MLd nucleus mesencephalicus lateralis pars dorsalis - OM tractus occipitomesencephalicus     

Spatial organization and interneuronal relations in various areas of the neocortex in Cetacea

The data on pyramidal neurons joining in the parietal and temporal areas of the dolphin neocortex by means of apical dendrites fasciculi are presented. The fasciculi also contain dendrites of spindle-like and stellate cells. The vertical fasciculi of the dendrites unite neurons of the layer V and of the sublayer III2. In the sublayer III1, after dichotonic division of the apical dendrites, fasciculi of the second order are formed, to them the dendrites of the pyramidal neurons of the sublayer III1 and the layer II join. Several forms of the interneuronal contacts have been revealed: axo-dendritic, axo-spinous and dendro-dendritic. Synaptic complexes of the converged and divergent types have been shown. A suggestion is made on formation of larger neuronal modules++, having common afferent entrance and demonstrating selectivity to the stimulus properties.     

Specialization for underwater hearing by the tympanic middle ear of the turtle, Trachemys scripta elegans

Turtles, like other amphibious animals, face a trade-off between terrestrial and aquatic hearing. We used laser vibrometry and auditory brainstem responses to measure their sensitivity to vibration stimuli and to airborne versus underwater sound. Turtles are most sensitive to sound underwater, and their sensitivity depends on the large middle ear, which has a compliant tympanic disc attached to the columella. Behind the disc, the middle ear is a large air-filled cavity with a volume of approximately 0.5 ml and a resonance frequency of approximately 500 Hz underwater. Laser vibrometry measurements underwater showed peak vibrations at 500-600 Hz with a maximum of 300 μm s(-1) Pa(-1), approximately 100 times more than the surrounding water. In air, the auditory brainstem response audiogram showed a best sensitivity to sound of 300-500 Hz. Audiograms before and after removing the skin covering reveal that the cartilaginous tympanic disc shows unchanged sensitivity, indicating that the tympanic disc, and not the overlying skin, is the key sound receiver. If air and water thresholds are compared in terms of sound intensity, thresholds in water are approximately 20-30 dB lower than in air. Therefore, this tympanic ear is specialized for underwater hearing, most probably because sound-induced pulsations of the air in the middle ear cavity drive the tympanic disc.     

Ultrastructural features of neuromuscular junctions in the stapedius muscle of Gallus gallus

The ultrastructure of neuromuscular junctions in the twitch fibers of the stapedius muscle of Gallus gallus (domesticus) was investigated as part of a series of neurophysiological studies. Among the morphological features observed were elongated end-plates with numerous large and clear synaptic vesicles mixed with larger dense core vesicles and irregular or aperiodic “active sites” in the presynaptic membrane where synaptic vesicles were focused. The most remarkable features of these junctions were large synaptic clefts (50-80 nm) and the absence of junctional folds in the sarcolemmal surface. Unlike the large periodic junctional folds seen in the neuromuscular junctions of frogs and in the fast twitch fibers of the mammalian stapedius, the preparations studied only show small aperiodic invaginations (primitive folds) in the postsynaptic membranes. This morphological feature remains essentially constant from newly hatched to adult chickens. While these smooth junctions are consistent with earlier findings of inconspicuous junctional folds in the twitch fibers of the chicken posterior latissimus dorsi they are unlike those seen in the fast twitch fibers of the mammalian stapedius muscle, or other twitch fibers in general. The morphological findings of the present study may also suggest that the simple, unmodified neuromuscular junctions in the stapedius of Gallus may be a useful preparation for studies of synaptic membrane structures that employ the freeze-fracture technique.     

Anatomical basis for a technic of cutting flaps out of the musculus rectus femoris for creating a rectal sphincter apparatus

As demonstrate the surgical anatomy investigations of the m. rectus femoris performed in 100 preparations, obtained from corpses of persons belonging to various age periods, in connection with sphincteroplasty the vascular-nervous hilus of the muscle is projected at the level of the upper third of its medial part. The ascending branch of the lateral femoral circumflex artery with the vein of the same name and the muscular branch of the femoral nerve get into their composition. The intramuscular course of the vessels and nerves of the I-III orders of branching and that of the muscular fasciculi coincide. For the sphincteroplasty it is expedient to use muscular-tendinous flaps, cut out from the medial part of the musculus.     

Actomyosin ATPase activity of middle ear muscles in the cat

Summary When incubated for histochemical demonstration of actomyosin ATPase both the tensor tympani and the stapedius were found to contain two types of muscle fibres, one with high actomyosin ATPase activity, indicating a high speed of contraction, and one with low actomyosin ATPase activity, indicating a low speed of contraction. In the tensor tympani 59% and 41% of the muscle fibres had a high and low ATPase activity, respectively. The corresponding numbers in the stapedius muscle were 82% and 18%. These findings are discussed with reference to previous physiological and morphological studies.     

Hemomicrocirculatory bed of the muscles of the shoulder and forearm

By means of classical anatomical techniques: injection of contrast masses into the vascular network, macro-microscopic preparation, translucency, roentgenography, and some histological techniques, peculiarities of the hemomicrocirculatory bed in muscles of the human arm and forearm have been revealed. Small arteries of the 3d-4th order run along the muscle fiber fasciculi. In the center of the 2d order muscle fasciculus, in its internal perimysium, arteriole and venule (or 2 venules) run; from them into the 1st order fasciculus, precapillary arterioles and postcapillary venules, connected by means of capillaries, run. The arteriole and the venule, accompanying it, together with the precapillary arterioles and postcapillary venules, branching off them, form a unit of the microcirculatory bed of the arm and forearm muscles (module). Well developed intramuscular arterial anastomoses, presence of isolated structural-functional units of the hemomicrocirculatory bed ensure functional prosperity of the human muscles.     

Structural features of varicose dilatations of vasomotor nerves (according to data from a three dimensional reconstruction)

Ultrastructure of varicous dilatation of the axons composing small neuronal fasciculi in the sympathetic plexus of the rabbit coronary artery has been studied. According to the data of three dimensional reconstruction, space structure of three neuronal fasciculi has been restorted. Axons of every fasciculus form varicous dilatation at the same area along their course. A lemmocytic process, accompanying the axon as a thin cylinder at the intervaricous part flattens, in the area of varicous dilatations. and embraces all the axons, thus forming a peculiar functional unit of the neuronal fasciculus. From the data obtained and those of literature, it is possible to suggest that not only single axons situating in the nearest approximation to smooth muscle cells, but also single neuronal fasciculi having in their composition axons with varicous dilatation might effectively influence the smooth musculature of the vascular wall.     

Bilateral tympanic cavity infiltration with effusion in a patient with acute myeloblastic leukemia

A case of acute myeloblastic leukemia with bilateral tympanic cavity infiltration with effusion in addition to right facial and bilateral auditory nerve involvement is described. Tympanotomy demonstrated the presence of leukemic cells in the effusion of bilateral tympanic cavities. While repeated examinations of the cerebrospinal fluid using the cytocentrifuge failed to show any leukemic cells, it was suspected that the bilateral tympanic cavity infiltration was associated with meningeal involvement.     

Comparative morphology and evolution of the otic region in toothed whales (Cetacea, Mammalia)

The otic region in the skull of archeocetes and odontocetes is compared and interpreted with special emphasis on the morphology and suspension of the ear bones. In archeocetes, the periotic was obviously separate from the mastoid but still integrated within the skull via a long anterior and posterior process. The rotation of the cochlear part of the periotic was already obvious. The tympanic bone was attached to a decreasing number of neighboring elements, with the periotic becoming more and more important in the later archeocetes. The accessory air sacs of the tympanic cavity had invaded some of the adjacent skeletal elements and attained a moderate-to-remarkable extension. In the evolution of the odontocetes, the periotic and tympanic were successively uncoupled from the skull and combined to a new morphological and functional unit (tympanoperiotic complex). This uncoupling was mainly achieved by shortening the periotical processes and simultaneously extending the tympanic air sacs. For functional reasons, however, the periotic (posterior process) stayed in immediate contact with the mastoid, the latter remaining in the lateral wall of skull. In advanced marine dolphins, the bony sheaths of the accessory air sacs are largely reduced, presumably because of volume fluctuations in the tympanic cavity during diving. The perfect uncoupling of the ear bones from the skull obviously was an essential prerequisite for directional hearing, for effective ultrasound orientation and communication, and finally, for the striking development of the dolphin brain.     

A freeze-fracture study of muscle fibres infected with Trichinella spiralis

The muscle fibres of mice containing the infective-stage larvae of the nematode Trichinella spiralis have been studied by means of the freeze-fracturing technique. The larva lies in what appears to be a fluid-filled cavity within the cytoplasm of an altered muscle fibre. There is no membrane separating the cytoplasm of the nurse cell from the cavity surrounding the larva which is therefore truly intracellular, unlike many parasites that reside within a membrane-lined parasitophorous vacuole within the host cell. This altered muscle fibre, known as a nurse cell, lacks myofilaments but does contain extensive cisternae of endoplasmic reticulum; membrane-bound vesicles are budded off from the endoplasmic reticulum and traverse the cytoplasm towards the cavity containing the nematode where they apparently pass into the cavity. It is suggested that the contents of these vesicles are used to sustain the nematode. Attention is drawn to the similarity to giant cells that have been induced by the plant-parasitic nematode Meloidogyne in the roots of host plants and which sustain the nematode. The conversion of the muscle fibre into a nurse cell is probably brought about by the presence of a metabolic sink, the larval nematode, within the cell. This take-over of the control of a metazoan cell by another metazoan organism is most unusual and warrants further study.     

Analysis of the avian middle ear muscle contraction by strain gauge and volume and impedance change measures

1. Aves, unlike mammals, possess only one middle ear muscle, the stapedius. This muscle, which is innervated by a branch of the facial nerve, is exceptional in the respect that it alone exerts its effects on an entire physiological system, viz. the middle ear. 2. Measurements of the physiological effects of this muscle in situ revealed both fast and slow components: the fast component results from the active contractile machinery of the muscle while the slow component derives from certain passive, visco-elastic attachments. 3. The use of middle ear volume and impedance change measures in situ revealed a broader range of the muscle's physiological actions than was predictable by conventional strain gauge recording and/or histochemical studies.     

Reflexotherapeutic effects on biologically active points of the concha auriculae

By means of histochemical method, for revealing cholinergic nervous structures, and electron microscopy, innervation of biologically active points (BAP) and that of neutral areas of the rabbit ear skin has been studied, normal and after acu-, electro- and electroacupuncture. The BAP have more intensive vascularization and innervation, their specific feature is presence of well pronounced nervous fasciculi. The latter are formed by 6-10 fibers 1-6 mcm in diameter. The diameter of the fasciculi is within the limits 25-30 mcm up to 40-45 mcm. Under the electron microscopic investigation myelin and amyelin fibers are revealed in the nervous fasciculi. In the area of the epidermal basal layer and in the epidermis itself, single nerve terminals are found; they are considered as the point pain receptors. After acu-, electro- and electroacupuncture, intensity of the nervous fibers staining increases, thus demonstrating an increment of acetylcholine esterase activity. After insertion of acupuncture needles and after electrical irritation, the changes in the nervous and cellular elements in the BAP areas are studied electron microscopically. After the effects mentioned, mast cells situating in the BAP area become, as a rule, degranulated. After repeated electroacupuncture irritation of the BAP, an inflammatory focus appears with peculiarities specific for the given process. The reflexotherapeutic effect is supposed to be transferred via the nervous system. The mechanical irritation of the nerve fasciculi and the accompanying traumatization of the surrounding cellular elements initiate the mechanism of reflexotherapy.     

A histochemical characterization of muscle fiber types in the avian M. stapedius

The muscle fiber types and sizes in the M. stapedius (middle ear muscle) of the domestic chicken, Gallus gallus were determined histochemically on the basis of their reactions to myofibrillar adenosine triphosphatase (mATPase), succinic dehydrogenase and NADH diaphorase. Only type II fibers were identified at pH 9.4 and 4.2. At pH 4.6 three levels of activity were seen: high, intermediate and low. With the staining techniques three subtypes of fibers for oxidative enzymes, Types II1 (highly glycolytic), II12 (intermediately glycolytic and lipolytic) and II123 (highly lipolytic) were identified. Fiber diameter was also measured for the different fiber types. The average fiber diameter was around 20 micron for each fiber type. Although similar in size, the fiber types were markedly different in their histochemical properties. These findings plus those of earlier physiological studies suggest that the M. stapedius of G. gallus is a fast twitch, muscle with fibers of similar diameter showing mainly fatigue resistance characteristics.     

Prenatal development of the intrinsic nerves of the muscles of the human foot

Myelogenesis and blood supply of the intraorganic nerves have been studied in 4-6- and 7-9-month-old human fetuses. At first, the intramuscular nerves are presented as very thick fasciculi (the diameter is more than 90), thick (the diameter is from 50 up to 90) and single muddle neural fasciculi (the diameter is from 30 up to 50 mcm). The microcirculatory blood bed is formed at the expense of branches of the blood vessel-satellites and the blood vessels of the surrounding tissues and is carried out, without any interruption, along the whole extent. In 7-9-month-old fetuses the neural apparatus becomes more complex. The number of the middle neural fasciculi appear. On the background of fine neural fibers in the fasciculi a small part of the middle neural fibers appears, and in the musculus flexor digitorum brevis--single thick neural fibers. The intramuscular nerves have their own hemocirculatory bed presented by microvessels that are on the perineurium surface, in its bulck and among neural fibers.     

Localization and proliferation of lymphatic vessels in the tympanic membrane in normal state and regeneration

We clarified the localization of lymphatic vessels in the tympanic membrane and proliferation of lymphatic vessels during regeneration after perforation of the tympanic membrane by using whole-mount imaging of the tympanic membrane of Prox1 GFP mice. In the pars tensa, lymphatic vessel loops surrounded the malleus handle and annulus tympanicus. Apart from these locations, lymphatic vessel loops were not observed in the pars tensa in the normal tympanic membrane. Lymphatic vessel loops surrounding the malleus handle were connected to the lymphatic vessel loops in the pars flaccida and around the tensor tympani muscle. Many lymphatic vessel loops were detected in the pars flaccida. After perforation of the tympanic membrane, abundant lymphatic regeneration was observed in the pars tensa, and these regenerated lymphatic vessels extended from the lymphatic vessels surrounding the malleus at day 7. These results suggest that site-specific lymphatic vessels play an important role in the tympanic membrane.