摘要:

AbstractChick embryos were inoculated with influenza‐A virus over the blastoderm at 42–50 hours incubation (37°C). Surviving embryos were harvested 24 hours later, Grossly and microscopically, the developing brain exhibits a type of abnormality in which the neural wall is highly convoluted with folds projecting into the ventricular cavities, suggesting “overgrowth” of the neural tissue.A comparison of measurements on projection drawings of serial sections of virus inoculated and control embryos at comparable developmental stages indicates that the ventricular surface area, volume of brain tissue and volume of the ventricular cavity are markedly less in the experimental embryos, but average thickness of the brain wall is greater. There are fewer nuclei and mitotic figures in experimental embryos, although average nuclear and mitotic densities and mitotic index are approximately the same as control values.It is evident that the characteristic neural defect is not due to excessive growth, since the volume of brain tissue and number of cells are consistently less in experimental embryos. It is concluded that the virus infection results in an inhibition of growth of the brain wall, and that the increased thickness and foldings must result from collapse of the brain which in turn may be due to a decrease in the amount of ventricul

ISSN:0003-276X    

DOI:10.1002/ar.1091580102

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe right atrioventricular junction and A‐V node area in each of five human hearts was studied histologically in serial sections. The A‐V node of a 54‐year old female was reconstructed in four colors to provide a three‐dimensional model of cardiac relationships, blood supply, and nodal configuration. The nodal fibers demonstrated two laminations. A superficial layer was composed of longitudinally oriented fibers, whereas a deeper layer was composed of oblique and transversely directed fibers. The atrioventricular bundle fibers were always continuous with nodal fibers of the deeper portion of the A‐V node. Atrionodal fiber junctions occur along the superior, endocardial and inferior borders of the A‐V node and impart to these surfaces a spiked appearance. The potential significance of A‐V node structure to atrial cardiac conduction

ISSN:0003-276X    

DOI:10.1002/ar.1091580103

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

年代:1967

数据来源: WILEY

摘要:

AbstractAn ultrastructural study of the rat myometrium revealed the presence of a number of nerve bundles, many of which were associated with either muscle cells or blood vessels. The nerve fibers were found to contain agranular and granular vesicles of widely varying proportions and the spatial relationship between nerve fibers and muscle cells in the myometrium was comparable to that found in smooth muscle generally.A study of regions of close apposition between muscle cells showed three types of “cellular contacts.” In the first type the opposing muscle cells are separated by a gap of about 200Å with filamentous structures extending across the gap. In the second type the opposing plasma membrane are in direct contact. The third type consists of regions of cytoplasmic continuity between adjacent cells. It is suggested that the “cellular contacts” provide a path for impulse transmission between musc

ISSN:0003-276X    

DOI:10.1002/ar.1091580104

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

年代:1967

数据来源: WILEY

摘要:

AbstractBloodstream flow patterns have been outlined in the arterial outflow tract (ventricular outflow tract and bulbus arteriosus) of the chick embryo heart during the period in which septation takes place, Hemodynamic factors underlying flow changes during this period are discussed.The mapping of flow patterns did not support the concept of a conoventricular flange reported previously. Septation was found to take place between two separate and discrete bloodstreams.The cellular nature of the aorticopulmonary septum has been described. The spiral ridges that form this septum expand by cellular growth, explaining the ability of this septum to develop against the direction of blood flow. The aorticopulmonary septum divides about two‐thirds of the arterial outflow tract; the final partitioning of the most proximal portion of the outflow tract was found to take place by means of the apposition of endocardial cushion tissue masses.Failure of aorticopulmonary septum development (truncus arteriosus communis persistens) was found to follow fusion of the bloodstreams in experimental studies. In experimental aortic stenosis the appearance of a small left stream was found to be followed by the development of a stenotic aorta. Thus in the first instance the septum apparently cannot develop unless the streams remain separate and in the second case the size of the prhnordial bloodstreams appears to determine the diameter of the vesse

ISSN:0003-276X    

DOI:10.1002/ar.1091580105

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

年代:1967

数据来源: WILEY

摘要:

AbstractA connective tissue growth model based on the regeneration of rabbit calcaneal tendon following surgical excision is described. Tissues allowed to regenerate for various periods of time from two days to 240 days were studied histologically and compared with mature tendon.Rabbit calcaneal tendon regenerating for 14 days or longer was found to represent a rapidly grown, normal connective tissue obtainable in quantities sufficient for biochemical microanalysis and thus to provide a valuable connective tissue growth model. By allowing growth to proceed for 56 days, the model could be used to provide normal tissue morphologically approximating mature tendon.

ISSN:0003-276X    

DOI:10.1002/ar.1091580106

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe innervation of the aortic arch and associated arterial trunks was investigated in the pig by gross dissection, by microscopic examination of normal arterial walls, and by observation of degenerative changes following selective surgical interruption of right and left cervical vagi. It is concluded that the aortic depressor fibers of the pig are organized unilaterally, being distributed by the left vagus to arterial walls, and by observation of degenerative changes following selective surgical with the absence of a dissectable right aortic nerve, there was no histological evidence of sensory innervation in the walls of the brachiocephalic, right subclavian, bicarotid or right common carotid artery. The majority of depressor endings were located in the ventral wall of the aortic arch in a band extending between the origin of the left subclavian artery and the aortic attachment of the ligamentum arteriosum. A few were present in the dorsal wall of the aortic arch and the ventral walls of the pulmonary trunk and ligamentum arteriosum. The depressor fibers were thick, heavily myelinated, varicose, extensively branched and associated with numerous terminal and intercalated neurofibrillar corpuscles. The only epithelioid body observed was a poorly innervated, rudimentary paraganglion in the interval between the aortic arch, the pulmonary artery and the ligamentum arteriosum.

ISSN:0003-276X    

DOI:10.1002/ar.1091580107

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

年代:1967

数据来源: WILEY

摘要:

AbstractOocytes of the hamster, rat, Mongolian gerbil and squirrel monkey demonstrate an unusual “twin” or multilaminated arrangement of the rough endoplasmic reticulum. Two or more cisternae appose laterally apparently after the ribosomes vanish from the adjacent surfaces. A central electron dense leaflet, composed of filamentous components can be discerned between the apposed surfaces. Between two cisternae of the membrane complex found in hamster oocytes, narrow connecting pillars or walls also develop. The nuclear envelope frequently represents one cisternal element in the membrane complex, at which place nuclear pores are lacking. In rat oocytes the endoplasmic reticulum cisternae take on either a concentric form, apparently by end‐to‐end fusion of “twin” cisternal membranes, or form a spiral by several turns of the same cisternum. No functional role could be suggested for the observed specilization of the endoplasmi

ISSN:0003-276X    

DOI:10.1002/ar.1091580108

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

年代:1967

数据来源: WILEY

摘要:

AbstractThis electron microscopic study of 11 day old chick tibiae cultured for 7 and 14 days has demonstrated significant changes in the exposed, cut, cartilaginous surfaces of the explants. Many chondrocytes had degenerated near these surfaces and, in the lacunae of these cells, 640Å‐banded collagen fibrils appeared. The diameters of these fibrils varied widely and, sometimes, exceeded 4,000Å. The non‐banded filaments of the normal, cartilaginous, extracellular matrix were replaced by 640Å‐banded collagen fibrils near the cut surfaces of the explants. These fibrils had a narrower (500Å) and more uniform diameter than those in the lacunae of degenerated chondrocytes. This study also has confirmed the occurrence of osteogenesisin vitro. The collagenapatite and matrix‐cell relationships were similar to fiber (embryonic) bone. Two types of cells resembling osteocytes and osteoblasts were found in the newly mineralized matrix formed in culture. Mineralization in the zone of outgrowth was incomplete and focal. In some regions the hydroxyapatite crystals were larger than usual, measuring 1,000–2,000 Å in length. Longitudinal sections of collagen fibrils in the zone of outgrowth revealed electron‐dense granules along the course of the fibrils. These granules exhibited no preferred orientation with respect to the band or i

ISSN:0003-276X    

DOI:10.1002/ar.1091580109

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

年代:1967

数据来源: WILEY

摘要:

AbstractForelimbs of small adult frogs (Rana pipiens) were amputated and the stumps implanted with silver‐platinum bimetallic rods insulated except at the tips. The silver end was at the wound surface in some cases. In others, the platinum end was distally placed. Other animals received separate implants of short pieces of bare silver and platinum wire, with the silver piece placed near the wound surface. Controls consisted of animals with either no implant or implants of partially insulated silver or platinum wire.Only one of the control animals (one with a silver implant) initiated regeneration. Regeneration was minimal with the separate implants (25%), more frequent with the platinum end of a bimetallic couple at the wound surface (70%), and most frequent (83.4%) with the silver end of a bimetallic couple at the wound surface. In three cases in the last named series, lobulated cartilages reminiscent of wrist and hand elements differentiated. The results are ascribed to direct stimulation of the cells, electrophoretic transfer of information‐bearing molecules, or stimulation of ner

ISSN:0003-276X    

DOI:10.1002/ar.1091580110

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

年代:1967

数据来源: WILEY

摘要:

AbstractAn attempt to survey spontaneous teratogeny among nonhuman primates bred under laboratory conditions revealed interesting but nonconclusive results. Data on controlled breeding in 2950 animals representing 12 species yielded an estimated incidence of 0.44% malformations. No indication was found that other primates display more malformations than man, and the limited information available suggests that there may be fewer spontaneous defects in nonhuman forms.Macaques and baboons appear to respond in a similar manner and to the same types of extrinsic agents as does man. Thalidomide, Rubella virus and androgenic hormones produce similar defects in comparable dosage at equivalent stages in development in both groups. Several other agents thought not to be teratogenic in man have been realistically tested in primates and also found to be non‐teratogenic.Using thalidomide an attempt was made to determine the degree of sensitivity and delimit the susceptible period ofMacaca mulattato this drug. Typical limb malformations were obtained with a single dose of as little as 16 mg/kg between the twenty‐fifth and thirtieth days of gestation. Comparable doses at earlier and later ages were without effect, thus defining the susceptible period. In addition, evidence of a positive dose‐response relation and of a cephalocaudal gradient in teratogenesis was obt

ISSN:0003-276X    

DOI:10.1002/ar.1091580111

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

年代:1967

数据来源: WILEY