摘要:

AbstractMyometrial development from the prenatal to adult period was examined in rats and mice (1) by histologic and immunocytochemical methods with anti‐actin, ‐vimentin, and ‐laminin to assess cytodifferentiation of smooth muscle and fibroblastic cells; and (2) by morphometric procedures to assess quantitatively the expression of cellular orientation in the emerging inner circular myometrial layer. Uterine mesenchymal cells initially were uniformly vimentin‐positive, undifferentiated, and randomly oriented during the late fetal period. By the early neonatal period, three mesenchymal layers became recognizable histologically, the middle one of which (prospective circular myometrium) developed distinct circular orientation and differentiated into a layer composed of actin‐positive smooth muscle cells. The cells of the inner mesenchymal layer initially exhibited radial orientation. By 10 days postpartum, the outer longitudinal mesenchymal layer differentiated into bundles of smooth muscle cells representing the longitudinal myometrium. The inner mesenchymal layer remained vimentin‐positive and differentiated into the randomly ordered endometrial stroma. The cells of the middle and outer mesenchymal layers that were destined to form myometrium initially expressed vimentin throughout and then coexpressed vimentin and actin, but with time vimentin staining disappeared in the maturing smooth muscle cells as they expr

ISSN:0002-9106    

DOI:10.1002/aja.1001860102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of diethylstilbestrol (DES) treatment on myometrial development from the prenatal to adult period were examined in rats and mice by histologic and immunocytochemical methods using anti‐actin, ‐vimentin, and ‐laminin to assess cytodifferentiation of smooth muscle and fibroblastic cells, and by morphometric procedures to assess quantitatively the effect of DES on the expression of cellular orientation in the emerging inner circular myometrial layer. Neonatal rats and mice were treated with DES from day 0 (day of birth) to day 2 with dosages known to perturb myometrial development. Neonatal treatment with DES increased the degree of circular orientation within the uterine mesenchyme, an effect detectable following as little as 24 hr of DES treatment. This effect on spatial organization of the mesenchyme was followed by an increase in the thickness of the actin‐positive middle layer (prospective circular myometrium) of uterine mesenchyme during days 3–15; from day 15 onward, however, the circular myometrial layer began to fragment into irregular bundles of smooth muscle, and the longitudinal myometrial layer became thinner and more irregularly organized than controls. Vimentin localization in rats treated with DES neonatally was more intense than in controls within the circularly orientated uterine mesenchyme at 5 days. By 60 days the circular and longitudinal myometrial layers of DES‐treated animals showed strands and bundles of vimentin‐positive cells, which were not present in controls. Both rats and mice show comparable effects of

ISSN:0002-9106    

DOI:10.1002/aja.1001860103

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe association of fibronectin with the microfibrils of connective tissue was examined in the zonular fibers of the mouse eye by immunohistochemical methods at the light and electron microscopic level. Mouse eyes fixed in formaldehyde were embedded either in paraffin for immunostaining by the peroxidase–antiperoxidase (PAP) method or in Lowicryl for immunolabeling by antirabbit globulin antibodies bound to 5 or 15 nm gold particles. Ultrastructural studies were also carried out after glutaraldehyde perfusion.Both the PAP and immunogold procedures demonstrated the association of fibronectin with microfibrils. After immunolabeling with 5 nm gold particles, examination at high magnification localized fibronectin to fine filaments that appeared to be attached to the surface of microfibrils. The filaments extended outward singly or formed loose aggregates. Their diameter ranged from 1.2 to 3 nm, with a mean of 1.5 nm. Because of their similarity to the fibronectin molecules previously described after rotary shadowing, the filaments were likely to be fibronectin molecules themselves.Since fibronectin is known to have high affinity for the amyloid P component, a model is presented in which fibronectin filaments are bound to the amyloid P component making up the tubular core of microfibrils in mice. Evidence is presented that fibronectin filaments may link microfibrils to one another and thus insure the continuity and strength of zonular fibers. More generally, it is likely that connective‐tissue microfibrils, whether or not inserted into elastic fibers, are bonded through fibronectin to surrounding cells, collagen fibrils, or proteoglycans, and thus insure cohesion among connective tissue eleme

ISSN:0002-9106    

DOI:10.1002/aja.1001860104

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

年代:1989

数据来源: WILEY

摘要:

AbstractThree‐dimensional reconstructions from serial sections were used to examine postnatal lung development of rats reared in air (control) or oxygen. From birth to age 21 days, control lung volume increased ninefold, and the average volume of each ventilatory unit (all airspaces distal to a single respiratory bronchiole) increased seven times. There were approximately 5,000 ventilatory units at birth and on day 21, indicating that the lung grew by enlargement and subdivision of ventilatory units and not by their multiplication. Growth in hyperoxia (>97%) for 7 days had no effect on the number of ventilatory units but, compared to controls, total lung volume and ventilatory unit volume were reduced 32% and 16%, respectively. At birth there were 0.6 × 106alveoli, and at age 7 days in controls alveolar number increased 16‐fold while the average volume of a single alveolus fell to one‐sixth that at birth. Exposure to hyperoxia for 7 days stopped alveolarization; the surface area to volume ratio (Sa/V) of the ventilatory unit was lower, alveolar number was the same as at birth, and the alveoli present were large. At age 21 days, after 14 days of recovery in air, lung volume and ventilatory unit volume were greater than in controls but the Sa/V of the ventilatory unit was still depressed 20%. Alveoli from oxygen‐exposed lungs were larger than in controls, and a greater size distribution coefficient showed them to be more variable. A shape coefficient for alveoli did not change as a function of the animal's age or oxygen treatment; it demonstrated proportional growth of alveolar height and

ISSN:0002-9106    

DOI:10.1002/aja.1001860105

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe phases of mitosis were examined in the columnar cells at the base of duodenal crypts in adult male mice given an intravenous injection of3H‐thymidine and sacrificed 20 min later. The duodenum was fixed by immersion into glutaraldehyde‐formaldehyde, and the cells were examined in the electron microscope, with or without processing for radioautography.Interphase nuclei are characterized by the distribution of chromatin; aside from the cortical chromatin spread along nuclear envelope and nucleolus, there are chromatin accumulations that belong mainly in two different classes: (1) numerous chromatin “specks” ranging in size from about 5 to 70 nm and averaging 47 nm; (2) a few roughly circular or elongated chromatin “packets” measuring from 70 to 230 nm. Early prophase nuclei differ mainly by a large increase in the number of chromatin packets to 20–30 or more per nuclear profile; their average diameter is 128 nm. During mid‐prophase, the chromatin packets enlarge gradually to an average 221 nm diameter. Between mid‐ and late prophase, there is a further increase in diameter to 679 nm. At metaphase, the packets take on the appearance of mature chromosomes, and their diameter increases to 767 nm. At anaphase, daughter chromosomes migrate to each pole, where they fuse into a compact chromatin mass. At telophase, nucleo‐plasmic areas progressively enlarge within the chromatin mass and separate strands of chromatin, which gradually become segmented into chromatin clumps.Counts of mitotic cells show a high proportion of prophase and telophase nuclei. Calculation from the counts yields the duration of the phases, that is, 5.6, 0.2, 0.1, and 1.6 hr, respectively, for pro‐, meta‐, ana‐, and telophase.Finally, radioautography 20 min after3H‐thymidine injection shows labeling in 54% of the interphase nuclei, 85% of early prophase nuclei, and 73% of mid‐prophase nuclei, while there is no label in late prophase, metaphase, anaphase and telophase nuclei. In confirmation of previous light microscopic work, the S stage of the cycle begins when a cell is in interphase and continues through the early prophase and part of mid‐prophase. Moreover, the main sites of DNA synthesis are the chromatin specks during interphase and the cortical chromatin during early and mid‐prophase. The chromosome condensation taking place in the meantime may be separated into two main steps: (1) a slow, moderate condensation of the chromatin packets during early and mid‐prophase and (2) a rapid, pronounced one during late prophase and prometaphase

ISSN:0002-9106    

DOI:10.1002/aja.1001860106

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe transition from the tropho‐blastic plate stage to the early lacunar stage was examined in a series of implantation sites from the rhesus monkey, timed on the basis of the preovulatory estrogen peak, and prepared for transmission electron microscopy. This transition was compared with specimens from stage 5a, b, and c in the Carnegie collection of human embryos. The transition was marked by the differentiation of a new type of syncytial trophoblast—namely, a unilaminar microvillous polarized syncytium, which developed throughout the trophoblastic plate, forming characteristic intrasyncytial clefts. The rapid development of this type of syncytium created a nonclotting chamber for maternal blood wherever trophoblast intrusion into maternal vessels created confluence. Although the nature of the material in the Carnegie series precluded cytological characterization of the trophoblast, there is evidence that a similar transition occurs in human trophoblast and that in the human also the appearance of lacunae marks a change from an early invasive trophoblast to a situation in which growth is more signific

ISSN:0002-9106    

DOI:10.1002/aja.1001860107

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe cytology of early blastomeres ofXenopus laevisembryos was examined. Particular attention was given to the organization of the nuclear envelope of karyomeres (chromosome vesicles) and the endoplasmic reticulum (ER) at different stages in early cleavage cycles of frog development. Nuclear envelope formation was observed to occur rapidly around individual chromosomes during early anaphase, and karyomeres fused subsequently to yield the final nucleus during telophase. Endoplasmic reticulum in the perinuclear cytoplasm was observed to be vesicular during metaphase and cisternal in form during telophase. Following microinjection of rat liver rough microsomes into early blastomeres, heterologous ER components were identified by electron microscope immunocyto‐chemistry. The foreign ER was observed as large, reconstituted cisternae at stages in the cell cycle when the nuclear envelope was intact. Therefore, transplanted ER maintained the capacity to reconstitute in the cytoplasm of a rapidly dividing cell. In an attempt to better assess ER structure at the metaphase stage of the cell cycle, we next slowed down the division process by treatingXenopusembryos with anti‐microtubule agents. Treatment with critical concentrations of colchicine, nocodazole, or vinblastine led to cleavage arrest but not to inhibition of the nuclear cycle. Following such treatment, homologous ER was observed in a vesicular form at all stages of the nuclear cycle. Heterologous ER, however, identified by immunocyto‐chemistry in microinjected cells treated with nocodazole, displayed both vesicular and cisternal forms. We conclude that microinjected ER membranes exhibit cell‐cycle‐specific behavior, which is different from that of the hos

ISSN:0002-9106    

DOI:10.1002/aja.1001860108

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

年代:1989

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001860101

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

年代:1989

数据来源: WILEY