摘要:

AbstractThe hearts of 38 black‐footed ferrets (Mustela nigripes) were studied with the use of physiologic, microdissection, vascular injection and histologic methods. These animals had a mean heart rate of 265 per minute, a heart weight of 3.7–5.2 gm, and a mean aortic pressure of 139.5 mm Hg. The predominant left coronary artery supplied usually both the SA and AV nodes, as well as the AV bundle, bundle branches and most of the ventricular myocardium. The cells of a well differentiated cardiac conduction system increase in cytoplasmic diameter from the SA node to the distal bundle branches. A cartilaginous right fibrous trigone and thick anulus fibrosus form useful landmarks for delineating AV node and AV bundle relationships. Small size, discrete nodal masses and a unique coronary arterial pattern make this heart an ideal model for histochemical, ultrastructural, electrophysiologic and pathologic circulation resea

ISSN:0003-276X    

DOI:10.1002/ar.1091790402

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

年代:1974

数据来源: WILEY

摘要:

AbstractLongitudinal sections through the incisors of the rat show a continuous layer of ameloblasts on the labial surface of the tooth. This layer contains the entire sequence of developmental stages in enamel production. Using 1 μm Epon sections from the upper and lower incisors of 100 gm male rats, the ameloblast layer was divided into three main zones which were themselves subdivided into regions: (1)Presecretory zonewhich includes (a) region of ameloblasts facing pulp, itself comprising a posterior portion (upper 172 ± 35 μm; lower 187 ± 37 μm) and an anterior portion (upper 458 ± 28 μm; lower 503 ± 36 μm); (b) region of ameloblasts facing dentin (upper 1210 ± 81 μm; lower 1381 ± 90 μm). (2)Secretory zone, (a) region of inner enamel secretion (upper 2573 ± 141 μm; lower 4274 ± 160 μm); (b) region of outer enamel secretion (upper 1211 ± 60 μm; lower 868 ± 72 μm). (3)Maturation zone(upper 7335 μm; lower 10615 μm), (a) region of postsecretory transition; (b) region of maturation proper, consisting of portions of ameloblasts with striated border and portions of ameloblasts with unmodified apices; (c) region of pigmentation; (d) region of reduced ameloblasts.These regions are readily identified using clear cut morphological criteria. Length measurements made on a group of 40 rats established the reproducibility of this classification. Therefore, this classification will be used as a basis for future studies of ce

ISSN:0003-276X    

DOI:10.1002/ar.1091790403

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe number and spatial relations of muscle spindles in theextensor indicishave been determined. Approximately forty spindles lie adjacent to the motor end plate zone dispersed rather equally through this area of the muscle with a modest increase in density among the distally originating fibers. A study of the entire innervation pattern of this muscle has also been completed.These findings have greatly facilitated the isolation of spindles for electron microscopic study and attempts to perform in vivo recording from the sensory nerves of muscle spindles in this laboratory. It is now possible, with the aid of suitable magnification and stimulating and recording devices, to more rapidly find muscle spindles relative to the gross innervation and the easily located motor end plate zone.

ISSN:0003-276X    

DOI:10.1002/ar.1091790404

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

年代:1974

数据来源: WILEY

摘要:

AbstractHuman muscle spindles are isolated from muscle biopsies of Extensor Indicis. A spindle rich portion of muscle is removed, placed into a modified Kreb's solution and microdissected for spindles. Intramuscular nerves and blood vessels provide helpful locating guides. Spindles can be dissected free of extrafusal muscle with an adequate length of nerve for in vitro recording. Another portion of muscle is stretched and placed into a 5% glutaraldehyde fixative in 0.1 M cacodylate buffer. Spindles are dissected free, postfixed, dehydrated, stained, and then studied with the light microscope while in liquid Epon. The equatorial regions are identified, then removed and embedded for examination using the electron microscope. This is the first successful total isolation of viable human spindles. The combined procedures allow correlation of recordings from the primary sensory endings with the fine structure of spindles from normal persons and from patients with neuromuscular disorders.

ISSN:0003-276X    

DOI:10.1002/ar.1091790405

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe human fetal thymus was studied at stages from 9 to 20 weeks of gestation. At 9 weeks of gestation the human fetal thymus contained lymphoid cells and was vascular although it was not yet lobulated nor did it have a cortex and medulla. By 12 weeks the thymus was lobulated and at 14 weeks a cortex and medulla could be distinguished, although the medulla was often more densely cellular than the cortex. By 18 weeks there were many lobules and a mature looking cortex and medulla. Large lymphocytes at all stages of thymus development studied were irregular in shape and often had blunt pseudopodia‐like cytoplasmic extensions, or more slender cytoplasmic extensions. They also often possessed numerous elongated mitochondria, a large Golgi complex and strongly basophilic cytoplasm. Large lymphocytes were not attached to the epithelial cells by desmosomes although some of the cytoplasmic extensions from them were in association with extensions from epithelial cells. Primitive medium‐sized lymphocytes at all stages studied were round in shape and had fewer mitochondria than the large lymphocytes. Epithelial cells were much less basophilic than the lymphoid cells and usually contained aggregates of glycogen. Occasional macrophages were observed within the developing thymus after 12 weeks of gestation and one granulocyte was observed within the thymus at 9 weeks while numerous granulocytes were seen within an interlobular septa at 14 weeks of gestation. Vessels were present within the thymus at all stages studied and at 9 weeks some had a boundary between the blood and thymus which consisted of only a thin endothelial cell and its basal lamina rather than the usual boundary of an endothelial cell and its basal lamina plus an epithelial cell and its basal lam

ISSN:0003-276X    

DOI:10.1002/ar.1091790406

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe functions of the normal semispinalis capitis and splenius capitis muscles of fifteen subjects were evaluated electromyographically with bipolar fine‐wire electrodes. The voltage‐output data were integrated and analyzed by computer and showed that the main function of semispinalis capitis is limited to extension of the head. However, splenius capitis both extends the head and rotates it to its own s

ISSN:0003-276X    

DOI:10.1002/ar.1091790407

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe ependymal tanycytes lining the ventral basal region of the third ventricle were studied in female rats during different stages of the estrous cycle. At mid‐diestrus, the apical membranes of tanycytes were shown to be devoid of microvilli and of other surface irregularities. During proestrus, a multitude of microvilli and small bulbous protrusions characterize this region of the ventricular wall. These surface disruptions persist through estrus and disappear during diestrus. In addition, so‐called supraependymal cells were observed and counted. Their numbers also vary with respect to the estrous cycle. The significance of these changes is discussed with respect to a possible mechanism for transporting substances from the cerebrospinal fluid (CSF) to the parenchyma of the hypothalamus and to the circulat

ISSN:0003-276X    

DOI:10.1002/ar.1091790408

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

年代:1974

数据来源: WILEY

摘要:

AbstractElectron microscopy of the turtle sinus venosus shows an unusual neuron soma which is immediately surrounded by myocardial cells so as to form a somato‐muscular complex. Studies of 36 sections cut through this neuron soma indicate that 27.4% of the somal surface studied is directly covered by cardiac muscle cells without any intervening basal lamina. Similarly, 18.8% of the somal surface studied is in contact with unmyelinated axons which at places make typical axosomatic synapses. A coupling of peripheral cisterns of the sarcoplasmic reticulum and the sarcolemma exists at the somato‐muscular contiguity as well as at the border between cardiac muscle cells. It is suggested that neural influences upon the pacemaking activity of the turtle heart sinus can well be exerted through the somato‐muscular pathway. Additionally, an axon which is presynaptic to the neuron soma has been observed to be simultaneously in a synaptic relation with a cardiac muscle cell; a remarkable deviation from the classical picture of the efferent nervous outflow to the

ISSN:0003-276X    

DOI:10.1002/ar.1091790409

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

年代:1974

数据来源: WILEY

摘要:

AbstractIntact and denervated brown fat lobes of normal and cold‐exposed mice were studied by light and electron microscopy. Following two weeks of denervation in normal and cold‐exposed mice, denervated brown fat cells were hypertrophied because of lipid accumulation. In normal mice there was a transient increase in glycogen. In cold‐exposed mice, the quantity of glycogen in intact and denervated brown fat was greater than in normal mice. Mitochondria increased in size, and the number of cristae was greater in intact fat of cold‐exposed mice than in denervated brown fat. Carbon perfusion of blood vessels demonstrated a decreased capillary bed in denervated fat. Capillary constriction noted only in denervated brown fat is indicative of reduced blo

ISSN:0003-276X    

DOI:10.1002/ar.1091790410

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

年代:1974

数据来源: WILEY

摘要:

AbstractIn 2 dogs, 5 cats and 30 human cadavers the diaphragmatic innervation has been studied macroscopically and microscopically. General findings of previous authors regarding phrenic and intercostal nerve contributions have been confirmed and subdiaphragmatic connections from the coeliac plexus to the diaphragm have been clearly demonstrated. The presence of this viscerosomatic interconnection in half of the human subjects studied, highlights the possible importance of autonomic control of diaphragmatic musculature. The finding of comparable autonomic connections in dogs raises the possibility of pursuing the question experimentally by carrying out nerve degeneration studies. In addition the matter of surgical incisions in the diaphragm has been reconsidered and the suggested placements have been illustrated.

ISSN:0003-276X    

DOI:10.1002/ar.1091790411

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

年代:1974

数据来源: WILEY