摘要:

AbstractThe role played by cell addition, cell enlargement, and matrix deposition in the endochondral growth of the condyle was assessed in weanling rats by four approaches making use of the light microscope: morphometry,3H‐thymidine radioautography,3H‐proline radioautography, and immunostaining for the cartilage‐specific type II collagen.From the articular surface down, the condyle may be divided into five layers made up of cells embedded in a matrix: (1) the articular layer composed of static cells in a matrix rich in fibers presumed to be of type I collagen, (2) the polymorphic cell layer including the progenitor cells from which arise the cells undergoing endochondral changes, (3) the flattened cell layer in which cells produce a precartilagenous matrix devoid of type II collagen while undergoing differentiation in two stages: a “chondroblast” stage and a short “flattened chondrocyte” stage when Intracellular type II collagen elaboration begins, (4) the upper hypertrophic cell layer, in which cells are “typical chondrocytes” that enlarge at a rapid rate, actively produce type II collagen, and deposit it into a cartilagenous matrix, and (5) the lower hypertrophic cell layer, composed of chondrocytes at a stage of terminal enlargement while the cartilagenous matrix is adapting for mineralization.3H‐thymidine radioautographic results indicate that the turnover time of progenitor cells in the polymorphic cell layer is about 2.9 days. The time spent by cells at each stage of development is estimated to be 1.4 days as chondroblasts, 0.5 days as flattened chondrocytes, 2.3 days as the chondrocytes of the upper hypertrophic cell layer, and 1.1 days as those of the lower hypertrophic cell layer.Calculations referring to a 1 × 1‐mm square‐sided column extending from the articular surface to the zone of vascular invasion provide the daily rate of cell addition (0.0077 mm3), extracellular matrix deposition (0.0127 mm3), and cell enlargement (0.0302 mm3). Hence the respective contribution of the three factors to condyle growth is in a ratio of about 1:1.6:4. This result emphasizes the role played by cell enlargement in the overa

ISSN:0002-9106    

DOI:10.1002/aja.1001820302

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe epithelium of the respiratory bronchiole in the adult rhesus monkey consists of two populations: a pseudostratified epithelium with basal, mucous goblet, and ciliated cells located near the pulmonary artery (PA); and a simple cuboidal epithelium composed only of nonciliated bronchiolar epithelial (or Clara) cells in areas away from the PA. This study describes the pattern of differentiation of these two epithelial populations, and their relationship to the PA and to the time of appearance of alveoli. in the respiratory bronchiole of the rhesus monkey during the period of 90‐125 days gestational age (DGA). These events were related to changes in the adjacent parenchyma. Dissected airways of infusion‐fixed, critical‐point‐dried lungs were evaluated by scanning microscopy followed by light microscopy of the same airways. At 54% of gestation (90 DGA), the distal airway was lined by a mixture of ciliated and nonciliated cells. By 67% of gestation (110 DGA), the ciliated cells were confined to the epithelium over the PA. The underlying connective tissue initially was cellular containing few fibers but was fibrous by 76% of gestation (125 DGA). Alveolarization began near the most distal cartilage at 57% of gestation (95 DGA), the same period at which secondary septation occurred in the distal acinus. Thus, alveolarization occurred simultaneously in two centers: (1) the proximal centriacinar region in the vicinity of the most distal cartilage and (2) the distal lung parenchyma. The duration of centriacinar alvcolarization was short, approximately

ISSN:0002-9106    

DOI:10.1002/aja.1001820303

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

年代:1988

数据来源: WILEY

摘要:

AbstractAlthough diabetic neuropathy is well documented, diabetic myopathy is not, except for descriptions of diabetic patients with muscular weakness thought to be due to metabolic changes in the muscle. Muscle and nerve are dependent on each other for normal structure and function; since the peripheral nerve is damaged in diabetes, one would expect concomitant changes in the muscle. This study examines the cytoarchitecture of diabetic muscle. The extensor digitorum longus (EDL) muscles from 165‐day‐old C57BL/KsJdb‐mmice were examined using electron microscopy. Morphological analysis of the diabetic EDL revealed that a significant number of the myofibers, examined within the midbelly region of the muscle, exhibited various degrees of degeneration, signs of denervation, and abnormal lipid stores. Both myoneural junctions and muscle spindles showed significant signs of degeneration, denervation, and abnormal structure. Thus the morphologic changes seen could account for the physiologic changes seen in diabetic m

ISSN:0002-9106    

DOI:10.1002/aja.1001820304

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

年代:1988

数据来源: WILEY

摘要:

AbstractAn ultrastructural study by transmission electron microscopy (TEM) of the vertebrae of embryonic, larval, juvenile and mature medaka shows that each vertebra consists of a core of notochordal cells surrounded by a sheath of bone. The vertebral bone lacks either fully or partially embedded cells in the matrix throughout development. Bone matrix is secreted by a layer of cells that lies over the outer surface of the vertebral bone. During the early stages of osteogenesis, these cells secrete bone matrix all around themselves. However, because of the gradual flow of the newly synthesized bone matrix through intercellular spaces, matrix‐producing cells do not become trapped in their own secretion. In later stages of osteogenesis, these cells secrete matrix only toward the already‐deposited bone. This polarized matrix secretion allows the osteoblasts to stay always on the bone surface and never to become trapped in the matrix as osteocy

ISSN:0002-9106    

DOI:10.1002/aja.1001820305

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe development and maturation of fundic glands of Wistar rats were studied usingGriffonia simplicifoliaagglutinin‐II (GSA‐II) histochemistry at the light microscopic and electron microscopic levels.In adult rats, mucous neck cells and cells intermediate between mucous neck cells and chief cells were specifically labeled with GSA‐II, whereas other fundic gland cells were virtually negative.Ontogenetic studies revealed that GSA‐II positive cells appeared at the bottom of the gland by 21 days of gestation. With differentiation and aging, the elongation of the fundic gland continued, and the labeling intensity of the mucous neck cells increased by 3 weeks after birth. Cells intermediate between mucous neck cells and chief cells were discernible from 3 days after birth. Typical mucous neck cells appeared at 3 weeks after birth, when their labeling intensity with colloidal gold (CG) particles approximated that of adults. On the other hand, the reactive cell population gradually moved from the bottom toward the middle portion of the gland. Finally, the reactive cells were localized at the neck portion of the fundic gland.These results suggest that GSA‐II is a valuable marker for studying mucous neck cells and both their precursor cells and their de

ISSN:0002-9106    

DOI:10.1002/aja.1001820306

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe metacarpophalangeal joint of the progressive ankylosis mouse was examined at 4, 6 and 8 weeks of age by using electron microscopy and electron probe microanalysis. These studies describe the progression of the disorder, and they reveal three overlapping phases: pannus proliferation, chondrophyte formation and mineralization, and articular cartilage mineralization. The chondrophyte mineralized in a manner fairly similar to endochondrial bone, whereas articular cartilage mineralized by advancement of a calcification front across the cartilage. Synovial crystal phagocytosis was also observed. The progressive ankylosis mouse should be an important model for studying both crystal deposition and abnormal articular cartilage calcification.

ISSN:0002-9106    

DOI:10.1002/aja.1001820307

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe structural effects of diabetes and subsequent insulin treatment upon the contractile and supporting elements of the rat myocardium were examined at progressive stages of both untreated and treated disease. Diabetes was induced by intravenous injection of alloxan, and tissue was examined after 6, 12, and 26 weeks. Insulin treatment began after 12 weeks of diabetes and tissue from these animals was examined after the same intervals. Within the cardiocytes, diabetes produced a focal yet progressive loss of myofibrils, transverse tubules, and sarcoplasmic reticulum, and separation of the fasciae adherens was evident at the intercalated disk. Mitochondrial damage was not evident. These cytoplasmic alterations were accompanied by intercellular and perivascular deposition of connective tissue, thickening of the endothelial cytoplasm with pinocytotic hyperactivity, and characteristic basal laminar changes. When insulin treatment began after 12 weeks of diabetes, most, but not all, of these changes were reversed, and this reversal was essentially complete within 6‐12 weeks. Even with longer periods of insulin treatment, cardiocytes still exhibited scattered areas of myofibril loss and extracellular matrix was retained. In contrast, diabetic changes in the intercalated disk and capillaries, including their basal laminae, were completely and rapidly reversed. It is hypothesized that the structural manifestations of diabetic cardiomyopathy consist of two major components; the first is a short‐term, physiologic adaptation to metabolic alterations, while the other represents degenerative changes for which the myocardium has only a limited capacity for rep

ISSN:0002-9106    

DOI:10.1002/aja.1001820308

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe innervation of rat interscapular brown adipose tissue has been studied by light and fluorescence microscopy and electron microscopy after treatment with “false” adrenergic neurotransmitters 5‐ and 6‐hydroxydopamine. The vascular markers neoprene latex and thioflavin S were used to define the blood vascular arrangements within and around the tissue.Catecholaminergic innervation was revealed by fluorescence microscopy at both parenchymal and vasomotor sites. In animals injected with 6‐hydroxydopamine, this catecholaminergic fluorescence was extinguished in the parenchymal nerve distribution and markedly reduced in the vasomotor plexus.Identification of an extensive network of noradrenergic vasomotor and parenchymal nerve terminals was established by electron microscopy after 5‐ and 6‐hydroxydopamine administration, but unmarked terminals were also observed in both distributions. These unmarked terminals might represent an additional nonnoradrenergic nerve supply to interscapular brown adipose tissue.The thoracodorsal veins draining the fat pads are directly tributary to a large median perforating vein, which joins the azygos vein, and are also continuous with the axillary vein. In addition to the recognized vascular distribution pattern of lobular arteries supplying an abundant capillary plexus drained by lobular veins, direct arteriovenous anastomoses were observed within the interscapular brown fat pad. It is postulated that these additional vascular arrangements are determinant in the phenomenal increase in blood flow through brown adipose tissue during metaboli

ISSN:0002-9106    

DOI:10.1002/aja.1001820309

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

年代:1988

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001820301

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

年代:1988

数据来源: WILEY