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1.
Phletus P. Williams Joseph E. Gallagher 《In vitro cellular & developmental biology. Plant》1978,14(8):686-696
Summary Conventional methods of organ culture have proved unsatisfactory for mammalian lung because of the rapid collapse of the tissue
and the loss of its normal structure. In an effort to circumvent this problem and to provide a means for visualizing the cellular
relationships throughout the culture period, respiratory organs consisting of trachea and lungs of fetal or hysterectomy-derived
1- to 4-week-old pigs were embedded in warm 3% Noble agar in phosphate buffer silicone solution and cooled to firmness. By
use of a described cutting device, the respective organs were sliced into thin, 0.5- to 1.0-mm tracheal ring or lung explants.
These organ sections then were cultured by exposure to alternate gaseous and liquid-medium phases by rotation (12 rev per
hr) in sealed Leighton tubes fitted in a described rotator. In short-term culture experiments, explants were best maintained
in a culture-support medium containing Eagle's minimal essential medium, 20% fetal bovine serum, 0.5% lactalbumin hydrolysate,
and other supplements in a pH range of 6.5 to 8.2, and a NaCl concentration of 0.1m or less. By bright-field and scanning-electron microscopy, tracheal ring and lung explant cultures incubated for 2 months
showed intact, uniform and active ciliated epithelial surfaces which compared favorably with those of fresh preparations.
The lung cultures showed alveoli that remained expanded, and the cellular integrity of the tissues remained normal in appearance.
This new method provides respiratory organs as continuous records with exceptional cellular clarity and readily available
for histological processing. The organ cultures lend themselves well to pathogenesis studies in which subtle cellular changes
or a sequence of changes induced in pulmonary tissues are difficult to observe in the host. 相似文献
2.
Explants of lung tissue from 19-day gestational age fetal rabbits were maintained in organ culture in medium with or without fetal calf serum for 1 to 11 days. Based on the results of biochemical and morphological studies it was apparent that the type II pneumonocyte differentiated in vitro at a time similar to that which occurs with maturation in vivo. The epithelial cells of the presumptive alveoli were undifferentiated at the start of incubation, but within 9 days developed increased amounts of Golgi apparatus and rough endoplasmic reticulum, many microvilli on the luminal surface and numerous lamellar bodies. Secreted lamellar bodies and tubular myelin figures were observed in the lumina of cultured explants. The incorporation of [3H]choline into phosphatidylcholine by lung tissue explants maintained in medium containing 10% fetal calf serum remained relatively constant for 7 days of incubation but thereafter increased two-fold. When explants were maintained in fetal calf serum-containing medium and cortisol (10?7M) or betamethasone (10?7M), the incorporation of choline into phosphatidylcholine was two to three times greater than that of explants maintained in serum-containing medium without cortisol. When explants of fetal lung tissue were incubated in the presence of cortisol without fetal calf serum there was no stimulatory effect of cortisol on phosphatidylcholine biosynthesis. Therefore, serum cofactors are necessary for the stimulatory effects of cortisol on fetal lung development. The specific activity of phosphatidate phosphohydrolase (PAPase) increased to very high levels during the culture period. In the presence of serum, cortisol or betamethasone had no effect on the specific activity of phosphatidate phosphohydrolase. 相似文献
3.
Development of fetal rat intestine in organ and monolayer culture 总被引:12,自引:0,他引:12
《The Journal of cell biology》1985,100(5):1611-1622
Maturation and differentiation of intestinal epithelial cells was demonstrated in segments of fetal rat small intestine, maintained for more than a month in suspension organ culture, by ultrastructural, biochemical, and immunological criteria. Over a 5-7 d period, fragments of fetal intestine evolved into globular structures covered with a single columnar epithelium ultrastructurally similar to suckling villus cells. Loose mesenchymal cells, cellular debris, and collagen were present inside the structures. After 6 d in culture, goblet cells, not present in the fetal intestine at day 18, were numerous and well developed. Intestinal endocrine cells were also observed. Immunofluorescence studies employing monoclonal antibodies specific for villus and crypt cells in vivo, and various enzyme assays, have demonstrated a level of differentiation and maturation of the cultured epithelial cells similar but not identical to that of suckling intestinal mucosa in vivo. Crypts and crypt cell markers were not observed in the the cultures. Addition of glucocorticoids to the culture medium resulted in the induction of sucrase-isomaltase but failed to promote most of the functional changes characteristic of the intestinal epithelium at weaning in vivo. Epithelial cells were identified in explants derived from the organ cultures by their specific expression of intestinal cytokeratin. Differentiation-specific markers, present in the epithelial cells in primary cultures, were lost upon selection and subculturing of pure epithelial cell populations. These results suggest a requirement for mesenchymal and/or extracellular matrix components in the maintenance of the differentiated state of the epithelial cells. The fetal intestinal organ cultures described here present significant advantages over traditional organ and monolayer culture techniques for the study of the cellular and molecular interactions involved in the development and differentiation of the intestinal epithelium. 相似文献
4.
Mesenchymal control of branching pattern in the fetal mouse lung 总被引:1,自引:0,他引:1
The effect of mesenchyme on specialization of respiratory epithelium in the fetal mouse was tested in organ cultures. Heterologous combinations were made between respiratory and non-respiratory lung epithelia and the corresponding mesenchymes. Isolated terminal respiratory buds of fetal mouse lungs were recombined with mesenchyme from chick lung parabronchi, mouse trachea or from the avascular, non-respiratory air sacs of chick lungs. Isolated non-branching chick air sacs were combined with mouse terminal bud mesenchyme or mesenchyme from the respiratory branches of chick lungs. Air sac epithelia branched in a pattern characteristic of the chick lung when combined with chick respiratory mesenchyme and in a pattern characteristic of mouse lung when combined with mouse terminal bud mesenchyme. Mouse terminal bud epithelia did not branch with either mouse tracheal mesenchyme or chick air sac mesenchyme but branched in a chick pattern with chick parabronchial mesenchyme. Electron microscopic examination of the cultures showed that all chick air sac epithelial cultures failed to produce surfactant (lamellar bodies) even when they branched. Control cultures of mouse terminal buds contained large numbers of lamellar bodies; mesenchyme which suppressed branching reduced the number of lamellar bodies to only a few in a small proportion of the cells. Culture medium supplemented with growth factors and hormones increased the number of lamellar bodies in heterologous mouse combinations but did not bring the number to control levels. Supplemented medium had no effect on lamellar body production by chick air sac epithelium. The results indicate that branching pattern is determined by the mesenchyme surrounding the epithelial primordium. However, the capacity to synthesize surfactant is determined by the source of the epithelium; mesenchyme may control the degree of expression but not the absolute presence or absence of the differentiated condition. 相似文献
5.
Theodore Fainstat 《In vitro cellular & developmental biology. Plant》1972,7(5):300-303
Summary Explants of whole ovaries and oviducts from postnatal rats were completely submerged during cultivation as organ cultures
in chemically defined medium. The oxygen concentration in the culture chamber was raised to over 90%, and the stainless steel
platform, used for cultures at the surface of the medium, was abandoned and excluded from further use. Thus, all of the periphery
of an explant had equal access to nutrients and oxygen. Throughout the ovarian explants the tissues appeared uniformly viable,
and mitotic figures were distributed evenly. These observations are in contrast to those on organs cultivated at the surface
of the medium where a lack of structural uniformity had been detected. The method has general application to a variety of
organs. 相似文献
6.
Theodore Fainstat 《In vitro cellular & developmental biology. Plant》1972,7(6):300-303
Summary Explants of whole ovaries and oviducts from postnatal rats were completely submerged during cultivation as organ cultures
in chemically defined medium. The oxygen concentration in the culture chamber was raised to over 90%, and the stainless steel
platform, used for cultures at the surface of the medium, was abandoned and excluded from further use. Thus, all of the periphery
of an explant had equal access to nutrients and oxygen. Throughout the ovarian explants the tissues appeared uniformly viable,
and mitotic figures were distributed evenly. These observations are in contrast to those on organs cultivated at the surface
of the medium where a lack of structural uniformity had been detected. The method has general application to a variety of
organs. 相似文献
7.
Hormonal regulation of beta-adrenergic receptors in fetal rabbit lung in organ culture 总被引:1,自引:0,他引:1
Explants of fetal rabbit lung were established on the 25th day of gestation. These were maintained in serum-free medium for periods up to 10 days. During this time, the cultures exhibited morphological changes typical of terminal lung differentiation. Morphological evidence was also obtained for synthesis and secretion of pulmonary surfactant in these explants. beta-Adrenergic receptors were identified in these lung explants. Exposure of the explants to 10(-7)M dexamethasone on the third day of culture resulted in a significant increase in the number of beta-adrenergic receptors in the tissue without a change in receptor affinity. The effect of dexamethasone in organ culture was dose-dependent, a maximum increase in receptor number being observed within 48 hours of incubation with a hormone concentration of 1 x 10(-7)M. Exposure of the explant tissue to 1 x 10(-7)M triiodothyronine resulted in no significant increase in the concentration of beta-adrenergic receptors and no change in receptor affinity. These results suggest that glucocorticoids may potentiate the effects of beta-adrenergic agents in the fetal lung by increasing the numbers of their receptors. The effects of triiodothyronine upon the fetal lung do not appear to be mediated by this mechanism. 相似文献
8.
Root organ cultures of red raspberry (Rubus ideaus cv. Titan) were established from two cm long terminal segments of adventitious roots induced in vitro on micropropagated shoot cultures. Growth of root organ cultures was almost entirely by initiation and elongation of lateral roots rather than by terminal elongation from the apical meristem of the original root explants. Indolebutyric acid (IBA) was required for lateral root initiation and elongation. The optimal IBA concentration for lateral root initiation decreased from 0.5 to 0.1 mg/L from the first to the fifth passage in culture. Two cm root explants initiated more lateral roots per unit length than four cm explants. Liquid Anderson's medium was superior to other basal nutrient and vitamin formulations tested. Root growth in liquid culture was stimulated by aeration. Root organ cultures also grew on media solidified with gelrite or agar. A rapid transfer technique was developed for subculturing these which involved cutting and transferring 1 cm discs of roots and underlying medium. Adventitious bud formation occurred spontaneously, but sporadically in liquid cultures, and was not influenced by cytokinin, auxin (spat) light, or chilling. 相似文献
9.
Regulation of the synthesis of the major surfactant apoprotein in fetal rabbit lung tissue 总被引:5,自引:0,他引:5
C R Mendelson C Chen V Boggaram C Zacharias J M Snyder 《The Journal of biological chemistry》1986,261(21):9938-9943
Antibodies directed against the major apoprotein of rabbit lung surfactant, a 29-36-kDa glycoprotein, were used to study changes in the levels of translatable surfactant apoprotein mRNA in rabbit lung tissue during development, as well as the effects of cortisol and cyclic AMP analogues on the levels of surfactant apoprotein and its mRNA in fetal rabbit lung tissue in organ culture. The major surfactant apoprotein and its mRNA were undetectable in lung tissues of 21-day gestational age fetal rabbits. Translatable mRNA specific for the major surfactant apoprotein was first detectable in lung tissues of 26-day fetuses, increased 25-fold on day 28, reached peak levels at day 31, and declined after birth. Incubation of 21-day fetal rabbit lung explants with cortisol in serum-free medium resulted in an increase in the specific content of the 29-36-kDa apoprotein. Cyclic AMP analogues and forskolin, an activator of adenylate cyclase, also caused a marked increase in the accumulation of surfactant apoprotein. When fetal lung explants were incubated with cortisol and dibutyryl cyclic AMP in combination, the specific content of the surfactant apoprotein was increased to levels greater than that of explants treated with either cortisol or dibutyryl cyclic AMP alone. These effects of dibutyryl cyclic AMP and cortisol on surfactant apoprotein accumulation were associated with comparable changes in the levels of translatable surfactant apoprotein mRNA. Thus, we have shown for the first time that the induction of pulmonary surfactant apoprotein synthesis during differentiation in vitro and in vivo is associated with an increase in the level of translatable mRNA and that cortisol and cyclic AMP increase both the accumulation of the major surfactant apoprotein and the corresponding mRNA in fetal rabbit lung tissue in vitro. 相似文献
10.
Taylor BK Stoops TD Everett AD 《American journal of physiology. Lung cellular and molecular physiology》2000,278(5):L1062-L1070
Protein phosphatase 2A (PP2A) is a key signal transduction intermediate in the regulation of cellular proliferation and differentiation in vitro. However, the role of PP2A in the context of a developing organ is unknown. To explore the role of PP2A in the regulation of lung development, we studied the effect of PP2A inhibition on new airway branching, induction of apoptosis, DNA synthesis, and expression of epithelial marker genes in whole organ explant cultures of embryonic (E14) rat lung. Microdissected lung primordia were cultured in medium containing one of either two PP2A inhibitors, okadaic acid (OA, 0-9 nM) or cantharidin (Can, 0-3,600 nM), or with the PP2B inhibitor deltamethrin (Del, 0-10 microM) as a control for a PP2A-specific effect for 48 h. PP2A inhibition with OA and Can significantly inhibited airway branching and overall lung growth. PP2B inhibition with Del did not affect lung growth or new airway development. Histologically, both PP2A- and PP2B-inhibited explants were similar to controls. Increased apoptosis was not the mechanism of decreased lung growth and new airway branching inasmuch as OA-treated explant sections subjected to the terminal deoxynucleotidyltransferase dUTP nick end labeling reaction demonstrated a decrease in apoptosis. However, PP2A inhibition with OA increased DNA content and 5-bromo-2'-deoxyuridine uptake that correlated with a G(2)/M cell cycle arrest. PP2A inhibition also resulted in altered differentiation of the respiratory epithelium as evidenced by decreased mRNA levels of the early epithelial marker surfactant protein C. These findings suggest that inhibition of protein phosphatases with OA and Can halted mesenchymal cell cycle progression and reduced branching morphogenesis in fetal rat lung explant culture. 相似文献
11.
C. A. Heckman 《In vitro cellular & developmental biology. Plant》1983,19(1):31-40
Summary Previous work in this laboratory demonstrated that rat respiratory airway epithelial cells grown from tissue explants undergo
concurrent division and differentiation in culture. In the present studies, this model system has been used to optimize conditions
for epithelial growth, with the goal of facilitating the culture of epithelium from other organs and species. Fibroblasts
appeared to limit the expansion of epithelial outgrowths; their growth was controlled by using delipidated serum, rather than
serum, in the culture media, with addition of adrenergic antagonists. In nonsupplemented media, rat tracheal fibroblasts doubled
in number in about 3 d. The doubling time was slowed to more than 9 d by the serum substitution in conjunction with the α-antagonist
phenoxybenzamine. Rat tracheal epithelial cultures maintained under identical conditions doubled in less than 4 d, so that
a growth advantage of threefold was achieved. The combination of conditions also seemed to inhibit growth of fibroblasts from
other species. However, even when the problem of fibroblast overgrowth was obviated, the respiratory airway epithelia of the
mouse, hamster, and marmoset failed to show self-sustaining growth in culture. The rat epithelium continued to grow for over
6 wk. A number of other organs from the rat, notably esophagus, skin, and salivary gland, showed self-sustaining growth after
removal of explants. Although epithelial outgrowths were formed by explants from certain organs of the hamster, only those
from the kidney and thyroid continued to grow after removal of the tissue explants. Therefore, growth failure in cultured
epithelia, quantitatively defined, is common and frequently unrelated to the problem of fibroblast overgrowth. The rat seems
to be the species of choice for studies on the isolated epithelia from most organ sites.
The research was sponsored jointly by Grant PCM 8110597 from the National Science Foundation, Washington, D.C., the Environmental
Protection Agency under Interagency Agreement 81-D-X 0533, the National Institute of Health Requisition 375014 GPCL, and the
Office of Energy Research, U.S. Department of Energy, under contract W-7405-eng-26 with the Union Carbide Corporation.
A preliminary report of this work appeared in the J. Cell Biol. 91: 32a, 1981. 相似文献
12.
Functional and ultrastructural effects of nontypeable haemophilus influenzae in a hamster trachea organ culture system 总被引:1,自引:0,他引:1
Joseph M. Mylotte Richard R. Stack Timothy F. Murphy John Asirwatham Michael A. Apicella 《In vitro cellular & developmental biology. Plant》1985,21(10):575-582
Summary A hamster trachea organ culture system was utilized to evaluate quantitatively the effects of a strain of nontypeableHaemophilus influenzae (NTHI) and culture supernatants of the same strain on ciliary activity. Tracheal explants were maintained in organ culture
for 96 to 144 h and ciliary activity was observed daily with an inverted microscope. Explants continuously exposed to a strain
of NTHI had a progressive decline in ciliary activity which was significantly lower than uninfected controls evaluated concomitantly
by 48 h of exposure and thereafter. Histologic studies revealed a progressive degeneration of mucosal cells and exfoliation
of ciliated cells. Scanning electron microscopy showed little adherence of NTHI to the mucosal surface. Sterile broth cultures
of NTHI and supernatants of organ cultures infected with the same NTHI strain had no adverse effect on ciliary activity. Infected
tracheal explants treated with ampicillin 24, 48, or 72 h after continuous bacterial challenge had no significant decline
in ciliary activity compared to controls. The lack of adherence and the histologic changes observed when hamster trachea cultures
were infected with NTHI suggested a toxin might mediate the damage observed. Broth and organ culture supernatants, however,
produced no damage. Therefore, further studies are needed to determine the role, if any, of a toxin in the production of damage
to hamster tracheal explants by NTHI.
This work was supported by a Merit Review grant from the Veterans Administration and by Grant AI-19641 from the National Institute
of Allergy and Infectious Diseases. 相似文献
13.
Effect of cortisol on the synthesis of lamellar body glycerophospholipids in fetal rabbit lung tissue in vitro 总被引:1,自引:0,他引:1
The effect of cortisol on the rate of choline incorporation into tissue phosphatidylcholine was investigated in lung explants from fetal rabbits of 19-28 days gestational age. The explants were incubated in medium with or without fetal calf serum for up to 7 days. When lung tissues were incubated in serum-free medium, a stimulatory effect of cortisol on tissue phosphatidylcholine synthesis was found in explants from 21-, 24-, 26- and 28-day fetal rabbits; a stimulatory effect of cortisol was observed in 19-day fetal lung explants only if fetal calf serum was present in the culture medium. To assess directly the effect of cortisol on the synthesis of lamellar body phosphatidylcholine, choline incorporation into phosphatidylcholine associated with a purified lamellar body fraction isolated from lung explants of 21- and 28-day fetal rabbits was also investigated. Cortisol caused a marked stimulation of synthesis and accumulation of lamellar body phosphatidylcholine in lung explants from both 21- and 28-day fetal rabbits. The magnitude of the stimulatory effect of cortisol on the rate of synthesis of lamellar body phosphatidylcholine was always greater than the effect of cortisol on the rate of choline incorporation into lipids of tissue homogenates. The relative rates of synthesis of lamellar body phosphatidylinositol and phosphatidylglycerol were also significantly altered in lung explants from 21- and 28-day fetal rabbits by cortisol treatment. Lamellar bodies that were formed initially in the fetal lung explants were enriched in phosphatidylcholine and phosphatidylinositol and had a relatively low phosphatidylglycerol content. With cortisol treatment there was a decrease in the relative rate of synthesis of lamellar body phosphatidylinositol and an increase in the relative rate of synthesis of phosphatidylglycerol. The stimulatory effect of cortisol on the synthesis of lamellar body phosphatidylcholine was observed at an earlier time-point of incubation than was the effect of cortisol on the relative rates of synthesis of lamellar body phosphatidylinositol and phosphatidylglycerol. The temporal sequence of the cortisol-induced changes in the synthesis of lamellar body glycerophospholipids, therefore, reflects that which occurs with maturation in vivo. 相似文献
14.
W. J. Hendelman N. de Savigny K. C. Marshall 《In vitro cellular & developmental biology. Plant》1985,21(2):129-134
Summary The purpose of this study was to compare the development of organotypic cultures in defined medium versus nutrient containing
serum and embryo extract (EE). Explant cultures of cerebellum with or without locus ceruleus were grown in the Maximow system
and monitored in the living state and with histological stains. Thinner explants, fibronectin and a more frequent feeding
schedule were required to overcome the growth differences encountered using a defined medium. The final medium formulation
was arrived at by evaluation of living cultures and consisted of a basal medium (Dulbecco's minimal essential medium), a number
of hormones and other supplements, and a final glucose concentration of 750 mg %. Using a Golgi stain and histofluorescence,
it was shown that the three major types of neurons—Purkinje, deep nuclear, and locus ceruleus—developed similarly in the defined
medium and in serum-EE cultures. Myelination occurred in virtually all cerebellar cultures in defined medium and the onset
was earlier than in serum-EE cultures. These results indicate that differentiation of oligodendroglia and maturation of neurons
occur in a defined medium. Elimination of thyroid hormone delayed the maturation of the cultures, both neurons and myelin,
by 3–4 days.
This project was supported by a grant from Supply and Services (Canada) and from the Department of Health and Welfare (Canada).
The findings and opinions are the sole responsibility of the authors.
EDITOR'S STATEMENT This article describes adaptations of serum-free cell culture methods previously developed by other laboratories
to the organ culture of central nervous system tissues. Although it is difficult to develop reliable procedures for quantitative
analyses in cultures of this type, organ cultures provide unique advantages in the study of development, regeneration and
response to damage, organismal and cellular senescence and genetic abnormalities of the nervous system. Observations reported
here regarding effects of thyroid hormone on cellular maturation in this culture system may be valuable in future studies
in these areas. 相似文献
15.
Intracellular levels of adenosine triphosphate in hamster trachea organ cultures exposed to Mycoplasma pneumoniae cells or membranes 总被引:11,自引:0,他引:11
The amount of adenosine triphosphate (ATP) in hamster trachea organ cultures was determined with a technique based on light emission from a luciferin/luciferase/ATP reaction. The amount of ATP, expressed as ng per mg dry weight, was consistent in tracheal explants prepared from various animals and changed negligibly when explants were cultivated in vitro for several days. The amount of ATP was related directly to cellular activity and integrity in the epithelium since inactivation by heat or freeze-thaw rapidly depleted measurable ATP, and ciliary activity and ATP content were related directly. When tracheal explants were infected with 10(5) to 10(7) CFU of virulent Mycoplasma pneumoniae cells, both ciliary activity and ATP content in the tissue dropped dramatically after approximately 5 to 8 days (up to 85% and 60% decreases, respectively). Exposure of explants to 50 to 200 microgram per ml of purified M. pneumoniae membranes also caused significant decreases in ciliary activity and ATP. When explants were infected with attenuated or nonvirulent mycoplasmas, ciliary activity was only slightly decreased, while ATP values often rose slightly. The technology associated with the determination of ATP levels in tracheal explants should prove useful as a new, objective, analytical approach to cell viability in organ cultures. 相似文献
16.
James H. Resau Ph.D. John R. Cottrell Kathryn A. Elligett Eric A. Hudson 《Cell biology and toxicology》1987,3(4):441-458
Human esophageal, tracheal, and pancreatic ductal fragments were collected at autopsy after a postmortem interval of 12 hours or less and maintained in explant organ culture for 30 days. The viability and growth of the explants was assessed by morphology, LDH enzyme release, and cellular outgrowth. The viability and growth of the bronchial explant epithelium was directly related to the postmortem interval. Esophageal epithelial regeneration followed the desquamation of the superficial cell layers. Pancreatic epithelia appeared to grow more slowly and with less outgrowth than the other tissues. Epithelial cell growth along the explant surface and onto the culture dish appeared to proceed through the well-characterized process that follows cell injury, i.e., flattening, migration, replication, and differentiation. Thus, sufficient numbers of viable epithelial cells capable of regeneration were present in routine autopsy epithelium, but there was considerable variation from tissue to tissue and case to case. The most effective and accurate approach to follow when evaluating and predicting the growth and viability of these explants is by using a combination of morphologic, enzymatic and biologic assays. Errors in the interpretation of viability are possible when only one assay method is utilized. These tissues grown in explant organ culture are suitable for studies on the mechanism and response of epithelia to cell injury, recovery and wound healing.Abbreviations 4F-1G
4% formaldehyde, 1% glutaraldehyde
- HIFBS
heat inactivated fetal bovine serum
- IA
immediate autopsy
- LDH
lactate dehydrogenase
- OsO4
osmium tetroxide
- RA
routine autopsy 相似文献
17.
18.
Exogenous cyclic AMP and dibutyryl cyclic AMP decreased the relative ciliary activity values of tracheal organ cultures. In contrast, theophylline and cholera toxin were not ciliostatic. The use of a radioimmunoassay for cyclic AMP indicated that all of the tested substances increased intracellular cyclic AMP levels to some extent (from 3-fold for cholera toxin to almost 40-fold for dibutyryl cyclic AMP). Physical inactivation of explants by either freeze-thaw or heat destroyed all ciliary activity and greatly decreased intracellular cyclic AMP levels. Cyclic AMP levels of explants remained relatively constant during in vitro cultivation. Three strains of Mycoplasma pneumoniae were found to contain extremely low amounts of cyclic AMP. Infection of tracheal explants produced a significant decrease in relative ciliary activity, but only a slight decline in organ-culture cyclic AMP levels. 相似文献
19.
Masayoshi Kumegawa Taishin Takuma Eiko Ikeda Michie Nakanishi Satoko Hosoda 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,585(4):554-562
The hormonal requirements for functional differentiation of chick embryo pancreas were investigated by using organ cultures in chemically defined medium. The hormones tested were prednisolone, insulin and thyroxine, and the parameters examined were α-amylase (EC 3.2.1.1) and chymotrypsinogen (EC 3.4.4.5) activities, and the ultrastructure of the tissues. Addition of prednisolone alone to explants from 14-day-old chicken embryo pancreas for 3 days increased the activities of amylase and chymotrypsinogen in the tissues by 3.4- and 6.6-fold, respectively, those of tissues before cultivation. Neither thyroxine or insulin alone, nor both hormones together affected pancreatic exocrine differentiation. Thyroxine enhanced the effect of prednisolone on both enzymes, but insulin did not. When the explants were cultured in the medium containing all three hormones, maximum enzyme activities were observed; amylase or chymotrypsinogen activity being 7- or 18-fold, respectively, that of tissues before cultivation. But these three hormones were not simultaneously necessary. Morphological differentiation was also observed in explants cultivated in medium containing these three hormones. These results suggest that glucocorticoids are essential for normal differentiation of chick pancreas during the late fetal period, possibly with insulin and thyroxine, and also support the idea that pancreatic enzymes are controlled separately. 相似文献
20.
The hormonal requirement for functional differentiation of chick embryo pancreas were investigated by using organ cultures in chemically defined medium. The hormones tested were prednisolone, insulin and thyroxine, and the parameters examined were alpha-amylase (EC 3.2.1.1) and chymotrypsinogen (EC 3.4.4.5) activities, and the ultrastructure of the tissues. Addition of prednisolone alone to explants from 14-day-old chicken embryo pancreas for 3 days increased the activities of amylase and chymotrypsinogen in the tissues by 3.4- and 6.6-fold, respectively, those of tissues before cultivation. Neither thyroxine or insulin alone, nor both hormones together affected pancreatic exocrine differentiation. Thyroxine enhanced the effect of prednisolone on both enzymes, but insulin did not. When the explants were cultured in the medium containing all three hormones, maximum enzyme activities were observed; amylase or chymotrypsinogen activity being 7- or 18-fold, respectively, that of tissues before cultivation. But these three hormones were not simultaneously necessary. Morphological differentiation was also observed in explants cultuvated in medium containing these three hormones. These results suggest that glucocorticoids are essential for normal differentiation of chick pancreas during the late fetal period, possibly with insulin and thyroxine, and also support the idea that pancreatic enzymes are controlled separately. 相似文献