摘要:

AbstractSeveral clinical syndromes, including the DiGeorge syndrome, are characterized by clusters of developmental defects of the heart and great vessels with structures derived from the embryonic pharyngeal apparatus including thymus and parathyroids. The connective tissue derivatives of neural crest are necessary for the normal development of these structures, and there is new experimental evidence that depletion of neural crest causes defects similar to these clinical syndromes. Therefore it is proposed that many of these syndromes are due to inappropriate development of neural crest. The implications of this hypothesis include the predictions (1) that asplenia and certain other anomalies have the same etiology, and (2) that it is possible to observe the effects of teratogenic agents upon a cellular population (neural crest) at the time when it is being altered, rather than waiting until definitive organs may be examined.

ISSN:0003-276X    

DOI:10.1002/ar.1092090102

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

年代:1984

数据来源: WILEY

摘要:

AbstractActin constitutes a major component of the cytoskeleton of human polymorphonuclear leukocytes (PMNs). In this study, we present a comprehensive view of the organization of actin in various PMN regions and functional states. Transmission electron microscopic observations were made on whole mount, migrating, and phagocytizing PMNs. Positive identification of actin filaments was made throughS‐1 myosin subfragment labeling. In all PMNs studied, actin filaments were primarily organized as a three‐dimensional meshwork. The density of this meshwork was greatest within the cell cortex. At peripheral regions of nonpolarized (viz., no distinct head or tail region) and polarized PMNs, actin filaments organized into parallel bundles or overlapping arcs. These bundles or arcs were oriented either perpendicular or parallel to the cell periphery. At the base of the PMN, actin filaments converged upon dense, plaquelike condensations. This latter pattern of actin organization was also observed in some pseudopods at the cell front and in phagocytic processes engulfing bacteria. In areas of internalized bacteria, the surrounding actin appeared as a loose meshwork. Treatment of PMNs with the antiactin drug, cytochalasin B, revealed shearing of the peripheral actin meshwork, condensation of the meshwork around the nuclear region, and dissolution of the basal plaquelike condensati

ISSN:0003-276X    

DOI:10.1002/ar.1092090103

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

年代:1984

数据来源: WILEY

摘要:

AbstractExtracellular matrix is known to play an important role during development and maintenance of various tissues. In the present study, changes in two extracellular matrix glycoproteins, fibronectin and laminin, were investigated in skeletal muscle undergoing immune rejection. Purified antibodies against fibronectin and laminin were used to analyze the matrix by indirect immunofluorescence at various intervals after transplantation of extensor digitorum longus muscle in rats. Fibronectin and laminin were localized in the pericellular basement membrane zone of the normal myofibers; however, the cytoplasm was devoid of both glycoproteins. Transplanted muscle grafts underwent a process of degeneration and then an initial regeneration during the first 7 days. This regeneration effort ceased with the onset of muscle rejection in 14‐day transplants. At this time, fibronectin was seen in the cytoplasmic region as well as the extracellular matrix of myofibers and myotubes. At later time intervals, an increased intensity of staining for fibronectin was seen throughout the rejected muscle. In muscle grafts undergoing regeneration but not rejection (i.e., nonantigenic grafts), such an increase in the presence of fibronectin was not seen (Gulati et al., 1982). The distribution of laminin did not change during the rejection process and was localized in the basement membrane zone of myofibers and myotubes, although the overall configuration of the basement membranes was deformed and collapsed. It appears that the basement membranes are resistant to degradation, and staining for laminin persists in rejected muscle. These results show marked changes in the extracellular matrix of muscle undergoing rejection. The appearance of fibronectin during the initial stages of muscle rejection may have a causal relationship to the process of immune defence mechanism; however, the exact role of fibronectin remains elusiv

ISSN:0003-276X    

DOI:10.1002/ar.1092090104

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

年代:1984

数据来源: WILEY

摘要:

AbstractWe describe the SEM appearance of the rat endosteal bone lining cell (BLC) population, and the sequence of morphological changes of these cells as they self‐incorporate into unmineralized bone matrix (osteoid), establish intercellular connections, and construct lacunae. The osteoblast/nascent osteocyte series was progressively unsheathed by gentle digestion of the osteoid with 0.25% collagenase. The osteoblasts which leave the polygonally packed BLC compartment rapidly develop numerous complexly branched processes that contact the processes elaborated by previous generations of maturing and mature osteocytes. As osteoblasts mature and approach the mineralization front, they appear to lose processes. The mature cells begin to form osteocyte lacunae by depositing an asymmetric perimeter of woven collagen fibrils, such that as the cells roof‐over, the lacunae appear as pocketlike constructions. The collagen fibrils on the perilacunar matrix are oriented in a tangential or circular pattern, while those in the more distal matrix are arranged in a parallel pattern. With the completion of a lacuna, its wall appears to mineralize quickly, for lacunae could be recognized only when they are form

ISSN:0003-276X    

DOI:10.1002/ar.1092090105

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

年代:1984

数据来源: WILEY

摘要:

AbstractFibroblasts are distributed evenly throughout the periodontal ligament (PDL) of normal mice. In mice fed beta‐aminoproprionitrile (β‐APN) the fibroblasts undergo aggregation to form palisades of closely juxtaposed cells abutting pools of acellular collagenous matrix. Individual fibroblasts within these aggregates retain their polarized cytoplasmic organization and continue to synthesize and secrete collagen. However, unlike normal PDL fibroblasts, the β‐APN‐treated cells appear immobilized by well‐developed cell‐to‐cell adherens‐type junctions along their lateral surfaces. We studied collagen secretion from β‐APN‐treated fibroblasts by light and electron microscopic radioautography after injection of3H‐proline. Newly synthesized collagen was secreted from the distal ends of the β‐APN‐aggregated fibroblasts as a distinct band of labeled material, resembling the pattern of matrix deposition seen in osteogenesis and dentinogenesis. The radioactive band of collagenous matrix was displaced further away from the fibroblasts at 2 and 4 days after3H‐proline injection as more collagen was secreted.This pattern of radiolabeled collagen secretion confirmed previous observations that PDL fibroblasts are highly polarized and that collagen secretory granules are extruded from the distal or secretory pole of the cell. In normal PDL the even distribution of fibroblasts and the complex interrelationship of their distal cell processes leads to a diffuse pattern of silver grain deposition, masking the oriented flow of new collagen from the distal ends of individual fibroblasts.Analysis of electron microscopic radioautographs revealed that newly synthesized collagen was packaged and secreted from β‐APN‐treated fibroblasts via the normal cytop

ISSN:0003-276X    

DOI:10.1002/ar.1092090106

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe uptake and retention of a radiolabeled synthetic progestin, ORG 2058, was studied in the female reproductive system of the baboon. Four estrogen‐primed baboons were injected intravenously with 2.5 μ/kg body weight of3H‐ORG 2058. One animal, which served as a control, received an additional injection of 2.5 mg/kg body weight of unlabeled progesterone. One hour after the injections, the animals were killed and the uterus, cervix, oviduct, vagina, and labia were removed and processed for autoradiography. The cells in the germinative layers of the stratified squamous epithelium of the cervix, vagina, and labia demonstrated nuclear localization of the label. The columnar epithelium, both surface and glandular, of the uterus and cervix sequestered the synthetic steroid; however, the nuclei of the epithelium lining the oviduct were unlabeled. The nuclei of the fibroblasts and of the smooth muscle cells were labeled in all the organs studied. These preliminary observations suggest that there is a stage in the reproductive cycle in which progesterone receptors are contained in the stromal cells of the oviduct but are absent in the epithe

ISSN:0003-276X    

DOI:10.1002/ar.1092090107

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe house gecko (Hemidactylus frenatus) exhibits an ovarian cycle that can be divided into early follicular, vitellogenic, and luteal phases. Serial sections through the right ovary of animals in the three phases allowed us to quantify follicular size, condition, and number, as well as germinal bed activity. There are six to eight healthy, growing follicles in each ovary, arranged in a stepwise size hierarchy. This number does not vary among the three phases, even though one follicle becomes atretic and one ovulates during each cycle. Therefore, compensatory follicular hypertrophy occurs, leading to replacement of lost follicles and maintenance of the follicular size hierarchy.

ISSN:0003-276X    

DOI:10.1002/ar.1092090108

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe indirect immunoperoxidase method was used to identify albumin in hepatocytes of young rats before and after periods of starvation and during a normal diurnal cycle. All liver cells in fed rats contained an abundance of albumin, whereas hepatocytes from overnight fasted animals showed minimal amounts of the protein. Hepatocytes in rats on the diurnal cycle generally contained more albumin during the light phase than in darkness. At the beginning of the dark phase, certain hepatocytes were low in albumin and they were located primarily around portal canals. Halfway through the dark period, these cells had increased in number and were located closer to terminal hepatic venules. Overnight starvation of young rats profoundly lowers hepatocyte albumin and the time of highest liver cell albumin content in the diurnal cycle of fed, young rats is during the first half of the light period.

ISSN:0003-276X    

DOI:10.1002/ar.1092090109

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe alveolar septa are divided into two anatomically distinct portions: The thin sides consist of capillary endothelium, alveolar epithelium, and their closely apposed (often fused) basal laminae; the thick sides are characterized by prominent interstitial spaces, containing fibrils and cells, which separate the respective basal laminae. Vesicle numerical densities are comparable (approximately 400 vesicles/μm3cytoplasm) in the endothelial and epithelial cells on both sides of the septa. Mean vesicle diameters, however, are substantially less in the epithelial cells on both the thin and thick sides. The extent of both endothelial and epithelial attenuation is significantly greater on the thin sides of the septa. Further, epithelial attenuation is more marked than endothelial attenuation on both sides of the septa. The attenuated cellular portions, possibly because of their extreme thinness, are void of vesicles but provide relatively short diffusion distances (20–30 nm) from vessel or alveolar lumen to the basal lamina. Whether these structural differences between endothelial and epithelial cells contribute to physiologic evidence that describes the endothelium as more permeable than the epithelium remains to be establish

ISSN:0003-276X    

DOI:10.1002/ar.1092090110

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

年代:1984

数据来源: WILEY

摘要:

AbstractFifty‐three maturing bone marrow cells of the granulocyte cell series stained with Giemsa stain and magnified 1,000 times were scanned by a “computerized microscope” consisting of a LSI‐11/23 microprocessor and a black‐and‐white video camera attached to a “frame grabber.” Each sampled cell was digitized into 70 × 70 pixels, each pixel representing 0.04 μm of the real image. The pixel gray values ranged between 0 and 255. Zero stood for white, 255 represented black, while the numbers in between stood for the various shades of gray. The cells represented six different stages of granulocytic maturation: myeloblast, promyelocyte, myelocyte, metamyelocyte, band form, and polymorphonuclear granulocyte.A discriminant analysis program selected 19 features best distinguishing between the six different cell types and computed five canonical discriminant functions defining a Space in which maturation was studied. In the Space, distance between two cells serves as a measure of similarity. The closer two cells are, the more similar they are and vice versa. This measure was applied here to express the degree of similarity between the neutrophil maturation classes, and since they represent states in the neutrophil life history, it is applicable also as a yardstick for the quantitation of differentiation. In the Space, the life history of a cell is represented by a trajectory originating in the myeloblast and terminating in the granulocyte state. Displacement along the trajectory represents cell maturation that is expressed relatively to the least differentiated state of the myeloblast. The further a cell from this state the more mature it is. The same yardstick also serves for differentiation rate estimates represented in the Space by displacement velocities that are derived from the known “transit times” of a cell in each state. The methodology is also applied for cell production estimates.Unlike other “computerized microscopes” serving for cell classification, the instrument described in this study is primarily a cell‐comparator providing a precise measure of simil

ISSN:0003-276X    

DOI:10.1002/ar.1092090111

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

年代:1984

数据来源: WILEY