摘要:

AbstractThe dorsal motor nucleus of the vagus nerve (DMX) of adult cats and young kittens was studied by quantitative light microscopic methods. In normal animals, the DMX was found to contain no distinct subgroupings of neurons, based on somatic volume or Nissl pattern. Retrograde perikaryal responses to axotomy of neurons in the DMX were found to be of a more subtle nature than those seen in other types of neurons. Quantitative methodology applied to the DMX after cervical vagotomy permitted a better understanding of the results of axotomy than could be obtained by routine microscopic observations. Changes which occurred included a slight chromatolytic reaction, and a decrease in the volume of the nucleus followed by an increase in somatic volume. These morphological alterations were affected by the factors of age of the animal, time after axotomy, and length of the intact proximal axon stump. More pronounced perikaryal changes occurred when the vagus nerve was recut at a more proximal level five days after the first vagotomy. Interpretation of the data yielded the conclusion that most if not all neurons of the ipsilateral DMX contribute axons to the cervical vagus nerge. In addition, at least 10% of the neurons on the side contralateral to vagotomy showed signs of retrograde reaction. It was therefore concluded that there exists in the vagus nerve a population of axons with cell bodies located in the contralateral DMX.

ISSN:0003-276X    

DOI:10.1002/ar.1091890402

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

年代:1977

数据来源: WILEY

摘要:

AbstractContact sites between lymphocytes and between lymphocytes and macrophages were demonstrated by electron microscopy in the lymphoid follicles of the bursa of Fabricius. When compared with nonspecialized regions of the cell membranes, these contact sites were characterized by a decreased intercellular distance, subplasmalemmal densities and coated pits. Microfilaments, microtubules and coated vesicles of the subjacent cytoplasm were frequently associated with these contact sites. When the same cells were isolated and introduced into culture, they formed cluster‐like assemblies in which cells were closely approximated along broadly contacting surfaces. The morphology of the sites appeared to involve primarily the plasma membrane (including coated pits) and the cell coat. These observations indicated that the same cells of a given lymphoid tissue can form one type of contact site in vivo and another, dissimilar type of contact site, in vitr

ISSN:0003-276X    

DOI:10.1002/ar.1091890403

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

年代:1977

数据来源: WILEY

摘要:

AbstractTight junctions (zonulae occludentes) create a pericellular barrier to the diffusion of large molecules in non‐keratinizing mammalian epithelia. However, in cornifying epithelia such as the epidermis, the importance of tight‐junctional elements versus secreted intercellular lipid for barrier function is uncertain. In an attempt to resolve this question, we compared membrane structure in the stratum granulosum and stratum corneum of epidermis, esophagus, and vagina of newborn and adult humans and mice under both normal and various experimental conditions. We incubated pieces of epidermis in organ culture and infused tissues with lanthanum or horseradish peroxidase in vivo and in vitro. All were processed for electron microscopy of freeze‐fracture replicas or thin sections. Lanthanum seeped outward to the stratum granulosum in all tissues examined‐further apical migration was halted by lamellar‐body contents in skin. A similar pattern of intercellular lamellar lipid deposition and membrane structure occurred in all epithelia studied. Freeze‐fracture replicas of these obstructive regions revealed occasional, incomplete junctional strands (particularly in moist epithelia) and abundant lamellar material, butcompletezonulae occludentes were never encountered. A possible relationship between moisture and tight junction formation was further suggested by organ culture experiments during which brief incubations stimulated an increase in the number of junctional strands and diminished numbers of lamellar bodies. We conclude that, in the epithelia studied, the deposition of secreted lamellar body contents forms the barrier to water‐soluble tracer loss: tight‐junctional elements are either absent or too fragmentary to constitute an ef

ISSN:0003-276X    

DOI:10.1002/ar.1091890404

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

年代:1977

数据来源: WILEY

摘要:

AbstractFreeze‐fracture combined with quantitative electron microscopy of the intact human erythrocyte (RBC) and ghost revealed significant differences in their intramembranous particle coefficients. External (E) fracture‐faces of unfixed ghost membranes were found to contain 40% fewer particles than those of intact unfixed RBC. The particle distribution of the intact RBC membrane depended on the use of glutaraldehyde fixation and glycerol cryoprotection. Whereas glutaraldehyde‐ and glycerol‐treated cells disclosed 70% fewer E‐face particles than did intact unfixed cells, poly‐L‐lysine‐treated, intact, unfixed RBC showed no such differences. Treatment with a combination of poly‐L‐lysine and glutaraldehyde, however, increased the amount of E‐face particles while reducing those of the protoplasmic (P) face. The poly‐L‐lysine effect varied with its concentration and was unaffected by previous application of neuraminidase. Nor did the lectin phytohemagglutinin induce particle rearrangement in intact cells.Our data demonstrate that the processes of glutaraldehyde fixation and glycerol cryoprotection modify the RBC membrane by decreasing the number of E‐face particles present. In addition, the combination of poly‐L‐lysine and glutaral‐dehyde alters the affinity of some particles for one half of the membrane, suggesting that in freeze‐fractured RBC, chemical bonds formed at the extracellular surface of the membrane

ISSN:0003-276X    

DOI:10.1002/ar.1091890405

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to examine the neuroanatomical pattern of cells which concentrate3H‐estradiol in the brain and pituitary of a carnivore, the mink,Mustela vison.In addition, since the mink has one breeding season a year it was possible to compare the pattern and number of estradiol concentrating cells in the brains of estrous versus anestrous animals. Five female mink (three estrous; two anestrous) were ovariectomized, and one week later administered3H‐estradiol. The animals were sacrificed, and autoradiograms were prepared with the method for steroid autoradiography used routinely in this laboratory (Pfaff and Keiner, '73). The entire brain was sampled and subsequently analyzed with the aid of a light microscope.The majority of estradiol concentrating cells were found in the hypothalamus and limbic system, although a small number were seen in other structures. Specifically, structures containing a large number of estradiol concentrating cells were: the ventral lateral septum, the bed nucleus of the stria terminalis, the medial preoptic area, medial anterior hypothalamus, the ventromedial and arcuate nuclei of the hypothalamus, the medial and cortical nuclei of the amygdala, and the anterior pituitary. Structures containing a small number of estradiol concentrating cells were also seen in the telencephalon and diencephalon. The most posterior population of estradiol concentrating cells was in the central grey of the mesencephalon. No difference in the neuroanatomical pattern or number of estradiol concentrating cells was seen when the autoradiograms from estrous animals were compared to those from anestrous anim

ISSN:0003-276X    

DOI:10.1002/ar.1091890406

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

年代:1977

数据来源: WILEY

摘要:

AbstractIn mouse embryos varying in age from 9 to 20 somites the first closure of the neural groove was found to occur in the cervical region. The fusion process gradually proceedéd in rhombencephalic direction until it reached a level just caudal to the otic pits. Shortly afterwards the prosencephalic walls fused together independent of the rhombencephalic closure. This prosencephalic fusion process proceeded caudally in the direction of the mesencephalon until it reached the rostral portion of the rhombencephalon. In this region the two independent fusion processes met each other. In addition the prosencephalic fusion proceeded in rostral direction toward the anterior neuropore, which was the last part of the brain vesicles to close. Hence, the closure of the brain vesicles is not a zipper‐like process proceeding from the rhombencephalon to the anterior neuropore, but occurs at several places at the same time and proceeds in a rostral as well as in a caudal direction.At the cellular level considerable differences in the fusion process were found to exist between the various brain vesicles. In the rhombencephalon the first bridge between the two opposing walls was formed by surface ectoderm and neural crest cells. In the mesencephalon single squamous ectoderm and a few neuroepithelial cells established the first contact, whereas in the prosencephalon the apical ends of several neuroepithelial cells fused together to overbridge the gap between the opposing walls. The surface ectoderm cells subsequently covered the neuroepithelial bridge. In the region of the anterior neuropore the fusion was similar to that between the prosencephalic walls, the only difference being that in the anterior neuropore area many more darkly stained particles indicating cell degeneration, were present than in the prosencephalon. It is thus concluded that considerable differences exist in the fusion of the neural walls between the various brain vesicl

ISSN:0003-276X    

DOI:10.1002/ar.1091890407

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

年代:1977

数据来源: WILEY

摘要:

AbstractFollowing partial castration of the newt, the remaining testis hypertrophies until it reaches the normal testis mass for the current season of the year. The effect of seasonal changes in testis growth and morphology on the hypertrophy of the testis are discussed. Following partial ovariectomy of the newt, there is no regenerative response. The remaining ovarian fragment remains the same size or partially degenerates. No evidence could be found for regeneration of the gonad from non‐gonadal tissue following total gonadectom

ISSN:0003-276X    

DOI:10.1002/ar.1091890408

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe development of the follicle cells in fetal guinea‐pig ovaries has been examined in the electron microscope.The findings were as follows: at days 34 and 38 there were broad intercellular clefts within the germinal cords. However, a continuous layer of thin cytoplasmic processes from the follicle cells separated the germinal cords from the stromal compartment. The germinal cords were everywhere limited by a basal lamina. During all the period examined coated vesicles, possibly emptying their contents into the region of the basal lamina, were observed in the follicle cells.At days 42, 46 and 50 the cellular membranes were closely apposed with an intercellular distance of about 200 A. Complexes of deeply interdigitating folds of the membranes of neighboring follicle cells were observed. The follicle cells forming part of the primordial follicles at days 54 and 58 were characterized by a disappearance of these folds and by the appearance of bundles of microfilaments in the cytoplasm. These were especially numerous at day 66.At days 34 and 38 gap junctions were observed between the follicle cells, but not between the follicle cells and the germinal cells. During the entire period examined junctions resembling desmosomes without filaments were observed between the follicle cells as well as between the follicle cells and the germinal cells.The ultrastructure of the follicle cells is considered in detail and the functional significance of the findings discusse

ISSN:0003-276X    

DOI:10.1002/ar.1091890409

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

年代:1977

数据来源: WILEY

摘要:

AbstractA spaced serial section, electron microscopic study of the extensor digitorum longus of the 2‐day‐old rat was undertaken to determine whether all cells wedged between the basement membrane and the sarcolemma of a muscle fiber, regardless of their morphology, were true myosatellite cells. The muscle was relatively immature, containing groups of cells enclosed in a common basement membrane (clusters) and exhibiting primitive myoneural junctions. Cells of the muscle line included in the clusters were primary fibers, satellite fibers, myotubes in different stages of development and myosatellite cells. In single ultrathin sections, some early myotubes lacked myofilaments and were difficult to distinguish from myosatellite cells. Spaced serial sections revealed that all myosatellite cells have heterochromatic nuclei and a high nuclear/cytoplasmic ratio, and that all pale staining nuclei were found in cells with a lower nuclear/ cytoplasmic ratio, containing variable quantities of myofilaments. In addition to the cells of the muscle line, mast cells, fibroblast‐like cells and other “unclassified” cells were entirely or partially enclosed within the cluster's basement membrane. This study demonstrated that location alone or location and the morphological appearance of cells in a single ultrathin section failed to provide sufficient criteria to properly classify all of the cells found in neonatal muscle

ISSN:0003-276X    

DOI:10.1002/ar.1091890410

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

年代:1977

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091890401

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

年代:1977

数据来源: WILEY