The ultimobranchial body in Rana pipiens

Summary Hypercalcemia was induced in male frogs by injection of Vitamin D₂ and maintaining animals in calcium chloride water. The fine structure of the Ultimobranchial gland was examined 3, 7 and 14 days after the initial injection. The initial response observed after the third day was a depletion of secretory granules in addition to an alteration of nuclear shape and cytoplasmic hypertrophy. After seven days secretory granule depletion continued and early cell types occurred which indicated an increase in mitotic activity. There was also a demonstrable increase in the amount of ergastoplasm and hypertrophy of the Golgi apparatus. On the fourteenth day, the height of the epithelium was markedly increased while the underlying vascular network was enlarged and more intimately associated with the secretory parenchyma. The homeostatic mechanisms of the Ultimobranchial gland appear to include both a rapid secretory response upon stimulation and a cellular renewal system to replace exhausted cells. This suggests that such a glandular system provides a mechanism to supply a rapidly expanding cell population to meet the demands of an excessive depletion of secretory materials. The response of this gland to hypercalcemia supports previous studies which suggest that the Ultimobranchial gland is the probable source of the hypocalcemic hormone, calcitonin.This project was supported in part by funds provided by the Department of Anatomical Sciences and National Institutes of Health, Grant No. AM-11795.     

Immunofluorescent localization of calcitonin in the ultimobranchial gland of Rana temporaria and Rana pipiens

Summary Calcitonin-like immunoreactivity has been demonstrated by immunofluorescence in the cells of the ultimobranchial gland of two species of Rana, using an indirect (sandwich) technique with anti-pure porcine calcitonin serum. The possibility of cross-reactivity, between the amphibian hormone and anti-porcine calcitonin antibody, had been anticipated on account of the observation that injected porcine calcitonin lowered the plasma calcium levels in one of the species under investigation.     

Ultrastructure of the jugular body of Rana pipiens

Summary The jugular bodies in adult Rana pipiens, are surrounded by a capsule of mesothelium and connective tissue, and their parenchyma consists of cell cords arranged in a sinusoidal network. The cell cords are formed by irregular reticular cells, showing numerous filaments and joined together by zonulae adhaerents. The intercellular spaces are filled by reticular fibres and free cells. These latter are small and medium lymphocytes, lymphoblasts, and developing and mature plasma cells. Additionally, free macrophages, neutrophils and acidophils also occur. Sinusoidal blood vessels show thin walls with numerous filaments and pinocytotic vesicles. They exhibit a discontinuous basement membrane, and tight junctions frequently occur between endothelial cells. Occasionally, lymphatic vessels are found and the innervation is principally vasomotor, although nerve endings appear remarkably near reticular cells and lymphocytes. The jugular bodies of adult R. pipiens are plasma cell and antibody-forming organs, whose functional significance is discussed in relation to their ultrastructural organization.     

The origin of erythroblasts in Rana pipiens tadpoles

The origin of circulating erythrocytes in larval Rana pipiens was studied. The normal morphology of red cells in diploid and triploid larvae was established to evaluate the use of ploidy as a cell marker. Sufficient differences exist, and this characteristic was exploited as a means of introducing cells of known origin into the circulation of larvae.Reciprocal transplantations of prospective hemopoietic anlagen were made between embryos with differences in ploidy.Blood samples from mid-larval tadpoles having received a prior exchange of blood island material contained no erythrocytes of graft ploidy. Red cells from this area are short lived and do not act as stem cells for erythrocytes produced in other areas.Erythrocytes of graft ploidy were present in blood samples from mid-larval tadploes having received a prior exchange of pronephric or mesonephric kidney anlagen. The stem cells of erythrocytes produced in the intertubular spaces of these structures develop in situ.     

Speciation in the Rana pipiens Complex

The long held view that leopard frogs (Rana pipiens complex)are a single widely distributed species is not correct. Fivesibling species are currently recognizable. These findings haveimportant implications on the use of leopard frogs in experimentalresearch.     

Observations on Mexican Rana pipiens

Mexican Rana pipiens now commonly sold in the United Statesdiffer morphologically and physiologically from their northerncounterparts. They resemble Arizona pipiens in appearance andbehavior, but their breeding cycle is distinctive. They aremost reproductively active in July and August. During late springand summer they can be ovulated readily and their pituitarygonadotropin levels are apparently high. Such is not the caseduring other times of the year. The role of Mexican frogs inteaching and research is discussed.     

Migration and Gene Dispersal in Rana pipiens

Although the dominant burnsi gene is widely distributed in Minnesotapopulations of the leopard frog (Rana pipiens) at uniformlylow frequencies, estimates of the effective size of the breedingpopulations suggest that a wider range of gene frequencies mightbe expected due to random genetic drift. Observations of thespring, summer, and fall migrations, however, indicate a levelof migratory activity sufficient to prevent local divergencein gene frequencies. Temperature appears to play a major rolein the springtime migratory and breeding behavior of Rana pipiensin Minnesota.     

Cell adhesion to extracellular matrix in normal Rana pipiens gastrulae and in arrested hybrid gastrulae Rana pipiens female X Rana esculenta male

Rana pipiens eggs fertilized by Rana esculenta sperm (ESC) hybrid embryos develop until gastrulation in control Rana pipiens embryos (PIP) and then show morphogenetic arrest. After arrest, ESC do not gastrulate but live for 5 days as blastula-like embryos. We studied the distribution of fibronectin (FN)-containing fibrils and integrin (INT) in PIP and ESC. There are many FN-fibrils in PIP organized in anastomosing networks radiating away from the center of individual cells and across intercellular boundaries. ESC have fewer fibrils compared to PIP. These fibrils are first located between cells in disorganized arrays. After arrest in ESC, when PIP are Stage 14 neurulae, many more FN-fibrils appear. INT-staining occurs in both embryos in similar patterns. In xenoplastic transplantations, we found that the extracellular matrix on the inner surface of the ESC blastocoel roof serves as a substratum for PIP cell migration. In an in vitro assay, we found more cell adhesion to FN-substrata in PIP than in ESC. Cell locomotion rates on FN-substrata were 1.70 +/- 0.85 microns/min for PIP but only 0.46 +/- 0.56 microns/min for ESC. We also found that the inner surface of the blastocoel roof from ESC can not promote cell adhesion and locomotion when Stage 11 fragments are used for conditioning but that Stage 14 fragments can deposit a FN-fibril-rich extracellular matrix which supports PIP mesodermal cell migration at a rate of 1.26 +/- 0.38 microns/min.