Postnatal development of structure and arrangement of tendon cells. A scanning and transmission electron microscope study in the rat calcaneal tendon.

The postnatal development of the three-dimensional structure and arrangement of the tendon cells in the calcaneal tendon of rats from 5 to 90 days of age were examined under the scanning and the transmission electron microscope (SEM and TEM). Exposed tendon cells were seen as winged bricks with a stellate profile in a cross section. Their slender perikarya were stacked successively in rows along the long axis of the tendon. The plate-like cytoplasmic processes, which were oriented along the perikaryal long axis, extended radially and joined those of the neighboring cells in rows. Therefore, the tubular channels for collagen fascicles were lined with the chained perikarya and their processes of the tendon cells. The cell rows were usually composed of many cells in developing stages, while short rows of one or two cells were observed in the fully developed stage. The cytoplasmic processes were the primary processes in the lateral extension, and their fine branches formed the secondary processes. The secondary processes were numerous at younger stages, showing a fine meshwork due to their mutual joining in the cross sections. In advanced stages, the meshes were coarse and the secondary processes were also perforated either with grouped fenestrations or large pores. In the fully developed stage, the secondary processes were fragmented on the perikarya, while the primary processes extended in the thin delicate sheets with large perforations. The findings in the present study suggest that the tendon cells are arranged in a three-dimensional network by their mutual joining. The tendon cells of the rat calcaneal tendon may not proliferate very much after birth, but do expand their nursing area in line with normal growth by an elongation of the main primary processes and a reduction of the secondary processes and perikaryal mass. The interfascicular clefts, which were caused by an intervention of either the processes at any developmental stages or the fragmented processes at a certain level of the tendon, may also play a role in the passage of tissue fluid.

Fiber arrangement of the rat splenic capsule with special reference to elastic fibers.

The fiber arrangement of the rat splenic capsule was examined under scanning electron microscope (SEM) after selective removal by chemical maceration of capsule components, in conjunction with examination of thin sections using a transmission electron microscope (TEM). TEM findings were compared to those of the guinea-pig, mouse and dog. Serosal cells of the rat splenic capsule showed labyrinthic channels that consisted of expanded intercellular spaces and tunnel-like spaces or slits in the basal cytoplasm. The channels contained fascicles of collagenous fibrils, forming a loose net on an underlying elastic lamina of densely aggregated elastic fibers. The fibrous tunica was an intermingled layer of elastic and collagenous fibers and sparse interstitial cells. The fibrous components were arranged more densely in the external layer than in the internal layer of the capsule. The elastic lamina comprised the outermost layer of the fibrous tunica in the intertrabecular region, but was situated deep in the trabecular region. Outward branches of the lamina in the trabecular region were arranged in a spiral. Intrachannel fibrillar fascicles were continuous, via fenestrations in the elastic lamina, with thick fascicles of collagenous fibers. The elastic lamina may play a role in effective contraction of whole spleen. In the guinea-pig, mouse and dog, elastic fibers were fragmented and not arranged in laminae. Typical smooth muscle cells were abundant in the dog. The channel spaces in the serosal tunica are discussed from the viewpoint of extravascular lymphatic flow for circulation of the peritoneal serous fluid.

Influence of landing on the supination and pronation in the foot joint.

The purpose of this study was to measure the changes of supination and pronation in the ankle joint at landing to quantify the influence of shock attenuation during landing. The subjects did two different motions, jumping down on the force platform from posterior and lateral views. The rear view of single foot contact in a jump from height of 30 and 60 cm showed a landing on the inside of the rear part of the foot (pronation) followed after about 0.03 sec by a rolling outward of the foot (supination). The variables describing changes in three angles of the ankle joint indicated that the standing position was more sensitive on the pronation and supination during ground contact.

[Neurogenous tumors in head and neck region].

We treated 26 patients with neurogenous tumors in the head and neck region in our hospital during the past 17 years. Their pathologic diagnoses were neurilenoma in 25 cases and paraganglioma in 1 case. The origin of the tumor was vagus in 4 cases, hypoglossal nerve in 3 cases, and sympathetic nerve in 3 cases. Neurological defect symptoms were observed in 12 cases after the surgery. The most common symptom was recurrent nerve palsy. The characteristic finding in the imaging study and the frequency of postoperative neurological disturbance were discussed.

Non-invasive method to detect motor unit contractile properties and conduction velocity in human vastus lateralis muscle.

The contractile properties and conduction velocity of motor units are estimated by using surface array electrodes during voluntary isometric contractions of the human vastus lateralis muscle. The subjects develop and maintain sufficient force to steadily discharge a given motor unit, assisted by visual feedback from an oscilloscope. The torque curve developed around the knee joint is triggered by an individual motor unit and averaged. 31 motor units in five subjects are studied. The twitch tension detected ranges from 3 to 27 m Nm with a mean of 12.3 m Nm. The threshold force ranges from 1.88 to 10.12 Nm with a mean of 5.48 Nm, which is 3% of the maximal voluntary contraction. The rise time ranges from 56 to 106 ms with a mean of 83 ms. The mean value of conduction velocity is 4.64 m s-1. The twitch tension is positively correlated to the threshold force (r = 0.839, p < 0.01), but has no relation to the other parameters. It is concluded that the use of non-invasive surface array electrodes provides the contractile properties of motor units and muscle fibre conduction velocity during weak contractions.

A scanning and transmission electron microscopic study of fiber arrangement in the hepatic capsule.

The arrangement of fibrous elements in the rat hepatic capsule was examined under a scanning electron microscope (SEM) after alkaline or acid maceration of the serous coat, in conjunction with examination of the thin sections using a transmission electron microscope (TEM). The elastic fibers appeared as thin threads in a densely meshed network, lying just beneath the serous coat. Their surface was granular with short rods in the materials fixed with paraformaldehyde. In contrast, the collagen fibers were observed as relatively thick threads, with fascicles of collagen fibrils that were uniform in size. These fascicles extended in various directions to form rough meshes that were traversed by small fascicles and anastomosed with each other. The fibrous branches of the elastic fibers extended on or into the underlying collagen fibers to be anchored, while the collagen fibers converged on many areas of the liver surface, and were transferred into the interlobular connective tissues. The findings of the present study thus suggest that the fiber arrangement plays an effective role in the mechanical protection of the fragile liver cells and delicate serous cells from pressure and friction damage by the neighboring abdominal organs and walls of the abdominal cavity due to the elastic mobility of the subserosal elastic network in addition to the possible slippery cushion of a serous layer on the serous cells.

[The effect of the motion of forefoot joint at the force exerted upon the floor during walking exercise].

In walking exercise the human body is exposed to external forces. Some of them are produced by constraints such as surface, shoes or opponent. In kick action of walking, the ground reaction force (GRF) is the most important external force. The magnitude of the GRF, its direction, and point of application have an influence on the load on the human body. The purpose of this study is to clarify the role of forefoot joint (artt. metatarsophalangeae) at the force exerted upon the floor during kick action of walking. The device used in this study to analyze the GRF and its three components consists of Kistler's force platform. Output from force transducer was collected online with a TEAC data recorder and MEM-4101 minicomputer. The impact force measurements were taken from the anterior-posterior force time curves at the take-off for 1 subject walking 10 trials at 2 m/sec with 2 different pairs of shoes (Shoes 1: thin sole of 4mm, and Shoes 2: thick sole of 40mm) and without shoes. High speed (200f/sec) cinematography was also used to analyze the angular displacement of forefoot joint at the take-off of walking exercise. The force acting at the forefoot joint may produce the anterior-posterior force of the GRF which is defined as the propelling power acting on the human body during walking exercise. The result showed that the impact force peak occurred 40-60 msec before take-off and the propelling part of kick action accounted for only about 6% of the external force.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle contractile properties by surface electrodes compared with those by needle electrodes.

We measured the contractile properties of the first dorsal interosseous muscle by surface electrodes and needle electrodes during submaximal voluntary contraction. Twenty-seven single motor units were recorded from 5 volunteers by surface electrodes, which were confirmed by subsequent needle electrode recordings. Twitch tension ranged from 0.6 to 10.0 g with a mean of 3.7 g based on an averaging method triggered by surface myoelectric signals, and the tension calculated from the needle myoelectric signals ranged from 0.8 to 11.7 g with a mean of 3.6 g. Rise time ranged from 33.9 to 81.6 msec with a mean of 49.4 msec for the surface electrode recordings, and from 33.0 to 73.2 msec with a mean of 50.8 msec for the needle electrode recordings. The obtained data of surface electrode recordings indicated a high correlation with that of the needle electrode recordings, r = 0.92 (P < 0.001) for twitch tension and r = 0.91 (P < 0.001) for rise time. We also found a positive correlation between threshold force and twitch tension (by surface electrodes: r = 0.71, P < 0.05; by needle electrodes: r = 0.77, P < 0.05). Our studies indicate that it is possible to record single motor units by non-invasive surface electrodes provided that the unit has a threshold force of less than 2 kg.

Involvement of membrane excitation failure in fatigue induced by intermittent submaximal voluntary contraction of the first dorsal interosseous muscle.

Factors involving muscle fatigue were studied at intermittent isometric contraction of the first dorsal interosseous muscle (FDI). Subjects made repeated contraction of 6 s, 40% of maximal voluntary contraction (40% MVC) (= target force) followed by 4 s rest until the target force could no longer be maintained. Measurement of MVC, recording of M wave evoked from the relaxed muscle, force measurement during tetanic electrical stimulation and measurement of serum K+ concentration were performed every 2 min during the fatiguing exercise and after 10 min of recovery. The declining rate of MVC force was always smaller than that of the force generated by 50 Hz stimulation, suggesting that no central nervous system (CNS) failure was involved. The amplitude and the area of the M wave declined while the duration of the wave increased, accompanied by the rise in serum K+ concentration. After 10 min of recovery, all parameters except the MVC force were restored. Thus we concluded that the failure in muscle membrane excitation, as well as the failure in excitation/contraction coupling, is involved in the deteriorating force generating capacity of FDI during intermittent isometric contraction.

Intercellular communication within the rat anterior pituitary gland: V. Changes in cell-to-cell communications as a function of the timing of castration in male rats.

Cell-to-cell communication by gap junctions was investigated in the male rat anterior pituitary gland following several experimental regimens involving castration. The regimens included the following animals: (1) Group 1, castrated at 10-day intervals from day 10 to 50 and sacrificed at 60 days of age; (2) Group 2, castrated every 10 days from days 10 to 50 and sacrificed 50 days after castration; (3) Group 3, castrated at 5 days of age and sacrificed every 10 days from day 10 to 60; or (4) Group 4, remained intact and sacrificed every 10 days from days 10 to 60. In all of the castrated animals, numerous so-called castration cells were scattered throughout the pars distalis of the pituitary gland, with occasional "signet ring cells" being observed. In Groups 1 and 2, the pattern of gap junction development and their number was no different from the intact control (Group 4). In contrast, the number of gap junctions in the animals castrated on day 5 remained very small even into adulthood. These data demonstrate that gonadal steroids are important in the initial development of gap junctions within the pituitary gland but are not necessary to sustain their presence once an animal becomes an adult.

Evidence that Müller cells can phagocytize egg-lecithin-coated silicone particles.

This study is designed to better understand the function of the Müller cells of the retina through the use of silicon particles that had been injected into the vitreous body of the eye and via an analysis of the number of gap junctions associated with these cells. Following intraocular injection of a silicone oil mixture into the rabbit retina, numerous small silicone particles less than 1 micron in diameter were found attached to the basement membrane of the inner limiting membrane, subjacent to the Müller cells. On the sites to which the silicone particles attached, the basement membrane was reduced in thickness or completely disappeared. The 'end-feet' of the cell membrane facing the silicone particles became concave appearing as if they were in the process of incorporating the particles into the cell. Similarly, the Müller cells occasionally extended cytoplasmic processes through the basement membrane and towards the silicone particles, as if to engulf them. Gap junctions were observed but only in association with the Müller cells. They were often found between the 'end-feet' of adjacent Müller cells or the 'end-feet' of one cell and very thin cytoplasmic process of a neighboring cell. On rare occasions, they were located between 'end-feet' of the same Müller cell. The percentage of 'end-feet' displaying gap junctions was 38 +/- 8% (mean +/- SE). These data suggest that the Müller cells are important in the maintenance of normal retinal function by their ability to phagocytize foreign substances and by their ability to transmit information to various parts of the retina through cell-to-cell connections established by gap junctions.

Evidence that hepatocytes can phagocytize exogenous substances.

Although the phagocytic action of Kupffer cells is well known, such a phenomenon has not been well documented for hepatocytes. Following the injection of a suspension of egg lecithin-coated silicon particles (0.5-1.5 microns in diameter) into the portal vein of rats, Kupffer cells showed minimal phagocytotic action, which was in contrast to the hepatocytes which displayed numerous phagocytized silicon particles. By comparison, when noncoated silicon particles of the same diameter as those that were coated were injected into the portal vein, the opposite observation was made. There was no uniformity in the ability of the hepatocytes to phagocytize either coated or noncoated particles from one lobule to another. Some showed active phagocytosis, while in others no evidence of such a process was observed. These data provide strong evidence for the selective phagocytic action of liver hepatocytes.

Intercellular communication within the rat anterior pituitary gland. III. Postnatal development and periodic changes of cell-to-cell communications in female rats.

Cell-to-cell communication by gap junctions was investigated in the female rat anterior pituitary gland from 10 through 45 days of postnatal development and in 60-day-old animals. Gap junctions initially appeared between adjacent folliculo-stellate cells on day 25. Their appearance in female rats was 5 days later than that observed in males (Soji et al., 1990). Gap junction number increased until the animals became 40 days of age, when they reached a level that resembled that found in adults. In addition, a correlation was evident between the frequency of gap junctions and stages of the estrous cycle, where they were most numerous during either proestrus or estrus. These results along with those previously published suggest that gap junction formation within the female rat hypophysis is in part modulated by both gonadal steroid hormones as well as prolactin.

[Skin approximation using Nd: YAG laser in head and neck surgery].

Laser is useful for surgery to cut, coagulate, vaporize and weld the tissue. Recently, low power laser was utilized for the treatment of ulcer, pain and vascular anastomosis. We applied low power Nd: YAG laser irradiation for skin approximation. An experimental study was carried out by using the Nd: YAG laser in approximating the surgically cut skin wound of guinea pigs. Healing of the wound was observed on post operative days of 3, 7 and 21, respectively. Laser approximation for the incised skin showed less scaring and faster healing than conventional suture technique. This laser technique will be beneficial as one of the new procedures of skin suture in clinical practice. The results were discussed from either technical or cosmetic standpoint.

Cytochemistry of Ca(++)-dependent adenosine triphosphatase (Ca-ATPase) in rat anterior pituitary cells.

In the present study, we demonstrate the localization of Ca(++)-ATPase in the anterior pituitary of the male rat. Ca(++)-ATPase was mainly distributed on the membrane system of the granular cells, which included the plasma membrane, the outer mitochondrial membrane, the enveloping membrane of secretory granules, the smooth endoplasmic reticulum and some components of the Golgi complex. No reaction product was detected on the membrane of the rough endoplasmic reticulum or that surrounding the lysosomes. A positive reaction was clearly observed on the membranes surrounding 'large' secretory granules, while that present on the membranes of the 'small' granules was comparatively weak. The cells which contained the 'large' granules were interpreted as growth hormone-secreting cells and those in which the 'small' granules were located as gonadotrophs. There were either no reaction or one that was barely detectable on the plasma membrane of the folliculo-stellate cells. These data along with our previous findings (Soji, 1982, 1984) suggest that the membranous enzymes are not uniformly distributed over all pituitary cells but rather are specific for a given cell population(s).

Muscle fiber conduction velocity and contractile properties estimated from surface electrode arrays.

Using an array of surface electrodes set 5 mm apart, we estimated the conduction velocities of muscle fibers during submaximal voluntary isometric contraction of human first dorsal interosseous muscle. The conduction velocity obtained by the averaging method ranged from 3.2 to 5.0 m/sec with a mean of 4.2 m/sec. Twitch tensions in the muscle detected during voluntary isometric contractions ranged from 0.31 to 5.97 g with a mean of 2.75 g based on an averaging method triggered by surface myoelectric signals. Threshold forces of the motor units varied from 120 to 930 g. The rise time of the force developed by isometric adduction ranged from 36.0 to 75.4 msec, with a mean of 55.4 msec. The conduction velocity of the muscle fiber showed a high correlation with the twitch (r = 0.71, n = 50; P less than 0.001) and threshold (r = 0.52, n = 50; P less than 0.001) forces, but a low one with rise time (r = -0.32, n = 50; P less than 0.05). The use of the averaging method with surface electrode arrays, especially for voluntary isometric contractions, shows that motor unit conduction velocity and contractile properties are functionally correlated.

Muscle fiber conduction velocity related to stimulation rate.

Muscle fiber conduction velocity in human biceps brachii muscle, produced by voluntary contraction and by contraction owing to microstimulation of a single motor unit, was measured with surface array electrodes. The conduction velocity of the fibers in the motor unit was calculated from the conduction time of the motor unit action potential along the electrode array and the electrode separation. With voluntary contraction, a conduction velocity of 4.25 +/- 0.43 m/sec (mean +/- S.D., n = 68) was obtained. In recording the surface EMG, the mean firing rate of the motor unit was 15.8 imp/sec (range 6-24 imp/sec). Significantly slower conduction velocity of 3.69 +/- 0.33 m/sec (mean +/- S.D., n = 56) was found after microstimulation (P less than 0.001). The higher the stimulation rate the higher was the conduction velocity. With increasing stimulus rates of 5, 10, 20 and 40 c/sec, the mean and S.D. of the conduction velocity were 3.74 +/- 0.33 m/sec (2.1% increase in the mean value to 1 c/sec stimulus rate), 4.16 +/- 0.37 m/sec (13.6%), 4.35 +/- 0.54 m/sec (18.8%) and 4.80 +/- 0.49 m/sec (31.1%), respectively. The firing rate for voluntary contraction was in the same range of the one obtained with 10-20 c/sec electrical stimulation, conduction velocity was the same in the two conditions. We conclude that measurement of muscle fiber conduction velocity should also be standardized with muscle fiber firing rate.

The estimation of conduction velocity in human skeletal muscle in situ with surface electrodes.

In the present study new methods were developed for estimation of conduction velocity using surface electrodes. The subjects were 4 healthy male volunteers, aged 23-29 years. EMGs were recorded from m. biceps brachii by several surface electrodes and a fine-wire bipolar electrode during weak isometric contraction with the elbow positioned at 90 degrees. Surface electrodes, 8 mm in diameter, were spaced along the course of muscle fibers at 20 mm intervals, while the bipolar fine-wire electrode was inserted in the middle of the muscle. The EMGs recorded on the magnetic tape were analyzed through a mini-computer system (ATAC-2300). Triggering a signal averager by spike potentials of single motor unit recorded by the inserted electrode, the average contribution of the single motor unit to the surface EMG could be extracted. The conduction velocity in m. biceps brachii determined from the averaged waves of each surface electrode was 4.6 +/- 0.5 m/sec (mean +/- S.D.). The conduction velocity estimated from the cross-correlation analysis between the EMGs of two different surface electrodes agreed well with the value obtained by the averaging technique mentioned above.