Tadpole Intestine Research Articles

Stress fibers in the mesenteric mesothelial cells of the large intestine of the bullfrog, Rana catesbeiana

Actin-containing cytoplasmic fibers were visualized in the mesenteric mesothelial cells of the large intestine of bullfrog tadpoles by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers were concurrently stained by immunofluorescence using antibodies to myosin or alpha-actinin. Electron microscopy showed the presence of bundles of microfilaments in the basal cytoplasm of the cells. Such fibers in the mesothelial cells may be comparable to the stress fibers present in cultured cells. The mesothelial cells initially formed axially oriented stress fibers when they changed from a rhombic to a slender spindle-like shape. On the other hand, stress fibers disappeared as cells transformed from elongated to polygonal shapes during the period of metamorphic climax. Expression of stress fibers in these cells appears to be related to the degree of tension loaded on the mesentery, which may be generated by mesenteric winding. These stress fibers in the mesothelial cells may serve to regulate cellular transformation. They may also help to maintain cellular integrity by strengthening the cellular attachment to subepithelial tissue against tensile stress exerted on the mesentery.

Binding of dexamethasone by hepatic, intestine, and tailfin cytosol in Rana catesbeiana tadpoles during spontaneous and triiodothyronine-induced metamorphosis

The binding of the synthetic glucocorticoid dexamethasone (dex) to Rana catesbeiana tadpole liver, intestine, and tailfin cytosol during both spontaneous and triiodothyronine (T 3)-induced metamorphosis has been examined. No change was observed in the dissociation constant ( K D ) in the liver or intestine during either spontaneous or T 3-induced metamorphosis compared with liver and intestine cytosol from the frog. The binding capacity (N) in liver cytosol of premetamorphic tadpoles (14.33 × 10 −14 mol dex/mg protein) was not significantly different from that found during prometamorphosis (stage XVIII) (11.50 × 10 −14 mol dex/mg protein) and in the adult frog (19.24 × 10 −14 mol dex/mg protein). Following the onset of metamorphic climax, however, there were significant reductions in N in liver cytosol, reaching a nadir at stage XXIV (0.38 × 10 −14 mol dex/mg protein). Binding capacity in premetamorphic tadpole intestine (19.60 × 10 −14 mol dex/mg protein) was significantly reduced following premetamorphosis. Values did not return to premetamorphic values in the frog intestine (6.54 × 10 −14 mol dex/mg protein) as occurred in the frog liver, nor were values significantly reduced following the onset of metamorphic climax (10.43 × 10 −14 mol dex/mg protein) when compared with prometamorphosis (11.58 × 10 −14 mol dex/mg protein). The binding capacity in the tailfin cytosol did not deviate from premetamorphic tadpole values (11.61 × 10 −14 mol dex/mg protein) through stage XXI (9.68 × 10 −14 mol dex/mg protein), the last stage in which sufficient tissue was available for analysis.

Proliferation and renewal of the epithelium in the intestine of young adult anadromous sea lampreys, Petromyzon marinus L.

The pattern of incorporation of [3H]thymidine in the intestinal epithelium of young adults of the anadromous sea lamprey, Petromyzon marinus L., was examined for up to 41 days using autoradiography. Compared with haemopoietic tissue of the fat column and the epithelium of the kidney, the intestinal epithelium does not rapidly incorporate the isotope. The epithelia of the anterior and posterior intestines and the hindgut regions all undergo a proliferation which, based on changes in the labelling index through time, suggest that a renewal of the epithelium takes place in each region. Most of the cells undergoing cell division are specialized absorptive cells but, in the posterior intestine and hindgut, mucous cells also undergo a variable rate of division. Although there is a slightly greater frequency of labelled cells at the bases of the longitudinal folds, there are no definite zones of proliferation in any region of the intestine. Instead, patches of dividing cells appear throughout the height of longitudinal mucosal folds. This is similar to the situation in parts of the intestine of larval lampreys and the intestine of amphibian tadpoles but unlike the case in other fishes.

Effects of prolactin and growth hormone on protein synthesis in larval and adult frogs (Rana pipiens).

AbstractFrogs and tadpoles (Rana pipiens) were treated with mammalian prolactin or growth hormone for several days, then injected with 14C‐leucine. Fourteen to sixteen hours later the animals were killed and the amount of label incorporated into protein of muscle, liver, and gut was measured.Growth hormone stimulated the incorporation of leucine into protein of gastroenemius muscle and small intestine, but not liver, of the frog. Prolactin had no effect on amino acid incorporation in any of these tissues in the frog. Prolactin stimulated the incorporation of leucine into protein of tail muscle, intestine and liver of tadpoles. The effect was not entirely consistent, and was of a smaller magnitude than was expected on the basis of the growth‐promoting effects of prolactin in tadpoles. This problem is discussed. Growth hormone had no effect on protein synthesis in any of these tissues in any experiment.

THE EFFECTS OF PROSTATE SUBSTANCE ON THE METAMORPHOSIS OF THE INTESTINE OF FROG TADPOLES

ArticleTHE EFFECTS OF PROSTATE SUBSTANCE ON THE METAMORPHOSIS OF THE INTESTINE OF FROG TADPOLESRobert W. HegnerRobert W. HegnerFrom the Department of Medical Zoölogy, School of Hygiene and Public Health, Johns Hopkins UniversityPublished Online:01 Jul 1922https://doi.org/10.1152/ajplegacy.1922.61.2.298MoreSectionsPDF (243 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat "THE EFFECTS OF PROSTATE SUBSTANCE ON THE METAMORPHOSIS OF THE INTESTINE OF FROG TADPOLES." American Journal of Physiology-Legacy Content, 61(2), pp. 298–299 Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation More from this issue > Volume 61Issue 2July 1922Pages 298-299 Copyright & PermissionsCopyright © 1922 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1922.61.2.298History Received 6 May 1922 Published online 1 July 1922 Published in print 1 July 1922 Metrics