摘要:

AbstractAn electromyographic study of elbow flexors and extensors was conducted using 20 adult human subjects to determine if cocontraction occurred during voluntary movement. The interplay of proprioceptive reflex influences arising in the primary and secondary endings of the muscle spindle and in the Golgi tendon organ provide the neurophysiological basis for cocontraction. Whether or not cocontraction occurs during a movement is dependent on the degree to which one proprioceptive influence predominates over the others. This in turn appears to be dependent on factors such as those described below.Incidence and degree of cocontraction was greater during extension than during flexion movements. This may be attributed to the influence of muscle spindle secondary endings.Cocontraction increased with increasing load. Proprioceptive reflexes arising in tendon organs may be involved in this phenomenon.No evidence was found to indicate that the incidence of cocontraction increased with increasing precision of movement. In general, cocontraction was less in skilled and strong subjects than in average subjects during all types of movements.Under the special circumstances of voluntarily attempted cocontraction, evidence of reciprocal inhibition of the antagonist appeared. Proprioceptive reflex activity from tendon organs and from muscle spindle secondary endings are implicated as primarily responsible for this inhibition.

ISSN:0003-276X    

DOI:10.1002/ar.1091700302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractMale and female A/Jax mice 10–18 days of age were given one, two, or three daily subcutaneous injections of Serpasil (Reserpine USP; 2.5 mg/kg) and sacrificed 24 hours after the last injection. Abdominal extra‐adrenal tissue was processed for electron microscopy to determine the effects of this catecholamine depleting drug on the dense cored cytoplasmic granules of the parenchymal chief cells.Electron microscopic investigations of sympathetic paraganglia from treated animals revealed a marked decrease in granule opacity as compared to that seen in cells from control animals. The cells with granules reduced in opacity following reserpine treatment could be consistently distinguished from those of non‐treated animals which led us to assume that the drug depleted the amine content from its storage site in the granule without completely destroying the granule structure. These results further substantiate our earlier speculations that the granules in abdominal paraganglion chief cells of the mouse contain catechola

ISSN:0003-276X    

DOI:10.1002/ar.1091700303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractThe connective tissue supports of the human female urethra have been investigated in 14 cadavers and 20 fetuses. In all cases the urethra was found to be suspended from the pubic bone by bilaterally symmetrical anterior, posterior and intermediate pubo‐urethral ligaments. The anterior and posterior ligaments were formed by reflections of the inferior and superior fascial layers of the urogenital diaphragm. The intermediate ligament represented a fusion of these fascial layers and no transverse perineal ligament was found.It is suggested that the term pubovesical ligament is a misnomer since this band of connective tissue passes from the pubic bone to the urethra and not to the bladder. It is thus analogous to the puboprostatic ligament of the male. An anatomical defect in the pubo‐urethral ligaments might be a contributing factor to urinary stress incontinence in the fem

ISSN:0003-276X    

DOI:10.1002/ar.1091700304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractCertain cells in the follicular epithelium of lizard(Anolis caro‐linensis)ovaries are connected to the oocyte by true intercellular bridges. Unlike other known intercellular bridges, these may form by secondary cell contact and membrane fusion rather than by incomplete cytokinesis. These intercellular bridges are abundant in previtellogenic tertiary follicles, and they contain glyco‐gen, ribonucleoprotein particles, and a dense, fibro‐granular material which may be exchanged between the two cells. Prior to the onset of yolk accumulation in the oocyte, the intercellular bridges and the pyriform cells from which they originated disappear from the follicular epithelium. The abundance of intercellular bridges in previtellogenic follicles suggests that they may be involved in the maintenance of dormant oocytes during periods of suspended reproductive activity and in the preparation of these oocytes for ensuing periods of intense metabolic activity associated with yolk accumul

ISSN:0003-276X    

DOI:10.1002/ar.1091700305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractQuantitative counts of the greater petrosal nerve fibers of the mouse with the electron microscope have shown that, on an average, 70.8% and 28.7% of the total nerve fibers (1,111) were unmyelinated and myelinated fibers respectively. Unexpected high incidence of unmyelinated fibers in the greater petrosal nerve may indicate that it contains a fair amount of sympathetic post‐ganglionic fibers. The unmyelinated fibers in the nerve may well represent parasympathetic preganglionic fiber

ISSN:0003-276X    

DOI:10.1002/ar.1091700306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractElectromyographic activity of the teres major and latissimus dorsi muscles using indwelling bipolar fine‐wire electrodes was recorded during motion of the arm and shoulder without resistance, against resistance, and during static resisted activity. The teres major is active during static motion and during motion against resistance with medial rotation, adduction, and extension of the arm. It is not active during motion without resistance, although latissimus dorsi usually i

ISSN:0003-276X    

DOI:10.1002/ar.1091700307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractArterial supply of the cervical spinal cord has been discussed with special reference to the radicular arteries. Thirty‐one human spinal cords have been studied with postmortem positive pressure injection techniques using coloured, and radio‐opaque media. Observations concluded that radicular arteries were main sources of supply to spinal cord except at the highest segments (C1C2C3), where intracranial vertebral branches contribute. Average number of significant radicular arteries is two or three, in two‐thirds of the specimens only one was present. These feeding radicular arteries usually enter into the spinal canal through the intervertebral foramina accompanying C4C5C6 nerve roots to join the anterior and posterior spinal arteries. Anterior, and posterior spinal arteries are probably of segmental origin, and there is only a sparse anastomosis between them. The common radicular artery divides into an anterior, and a posterior branch of which one predominates in size. Cervical radicular arteries may originate from subclavian branches other than vertebral, of these ascending cervical branch of thyrocervical trunk is most important. A terminal zone probably exists at highest thoracic segments where craniocervical, and thoracic radicular flows meet. The filling of the anterior spinal trunk in the cervical region depends on the availability of at least one major anterior radicular artery. Interruption of radicular supply may be precipitated by trauma, spondylosis and other lesions resulting into ischaemia, and myelopathy; the risk is greater if there is only one radicular artery which is inv

ISSN:0003-276X    

DOI:10.1002/ar.1091700308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractSebaceous glands from fetal rhesus monkeys have been studied from the onset of their differentiation to complete maturation. Sebaceous differentiation in fetuses closely parallels that in adults with the exception that agranular endoplasmic reticulum is virtually absent from differentiating cells during early ontogeny, whereas it is abundant in their counterparts in adult animals. As the adult pattern of sebaceous differentiation becomes established, the amount of agranular endoplasmic reticulum increases in these cells. Golgi zones are prominent in differentiating cells during early ontogenetic development.

ISSN:0003-276X    

DOI:10.1002/ar.1091700309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractIt is possible to divide the ultrastructural events which take place in the mouse Leydig cell during postnatal differentiation into two periods. The first period includes the changes taking place during the first three weeks after birth, whereas the second period comprises the events occurring from the fourth week on. During the first period the cytoplasm contains a poorly developed smooth endoplasmic reticulum. After the tenth day a slight increase in the number of vesicles and tubules of the smooth endoplasmic reticulum is observed. Clusters of glycogen particles (beta type) and lipid droplets are very numerous in this period.At the beginning of the second period the smooth endoplasmic reticulum hypertrophies considerably occupying a large area of the cytoplasm. This period is also characterized by the appearance of double‐walled tubules, of numerous interdigitations between neighboring Leydig cells and primary lysosomes in close relation to lipid droplets. A marked decrease in the number of glycogen particles and lipid droplets are also found. In the adult mouse (after day 50) numerous cisternae of the smooth endoplasmic reticulum are concentrically arranged (whorls).The formation of new membranes in the Leydig cell undergoing differentiation and the control of such differentiation are discusse

ISSN:0003-276X    

DOI:10.1002/ar.1091700310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY

摘要:

AbstractMicroradiographic, polarized light, phase‐contrast and scanning electron microscopic aspects of Tomes' granular layer were studied in undemineralized and demineralized premolar teeth from four dogs. The microradiographic studies show Tomes' layer to consist of a narrow zone of hypomineralized‐hyperorganic dentinal matrix subjacent to the cementum. The zone appears as a series of focal points in cross sections or as an interrupted line in apico‐coronal cuts through the tooth. Polarized light and phase‐contrast microscopy demonstrate a morphological pattern similar to that of the microradiographs. Scanning electron microscopy suggests one component of Tomes' layer to be fibrillar. Tomes' granular layer of dog teeth may be important in protecting the tooth from sudden insults or large occlusal forces transferred to dentine via the periodontal l

ISSN:0003-276X    

DOI:10.1002/ar.1091700311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1971

数据来源: WILEY