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No description available.

Thesis (doctoral)--Université Toulouse Le Mirail, 1998. / Cover title. Volume 2 consists of text of all 101 tales in French. Includes bibliographical references (v. 1, 227-229).

No description available.

There is no abstract available for this thesis.

Normal development of the urostyle is described during late stages of metamorphosis in five species of anurans: Xenopus laevis (Daudin), Bufo americanus Holbrook, Pseudacris triseriata (Wied), Hyla chrysoscelis Cope, and Rana pipiens Schreber.Tadpoles of these five species were reared in the laboratory, preserved in Bouin's fixative at various stages of metamorphosis (Gosner stages 34 to 44), and decalcified in 1% HC1 for 48 hours.A block of tissue containing the urotstyle was removed from the tadpole, embedded in paraffin, serially cross-sectioned, stained according to Mallory's trichromatic staining technique, and permanently mounted in Pro-Texx.The developing urostyle of all five species is composed of essentially the same cartilaginous elements: one pair of basidorsals above the notochord and' he hypochord below. Among the five species there is variation in such details as the number of spinal nerve foramina and the degree of fusion of the basidorsals; however, both the hypochord and basidorsals are quite similar in all five genera examined.The development of the urostyle as observed in this study provides insufficient basis for any conclusions about the phylogenetic trends in the five genera.The contradictory descriptions of the developing urostyle found in the literature appear to result from (1) varied methods of study (alizarin-staining of whole specimens or serial cross-sections), (2) the variety of species examined, and (3) the particular stage of development of the tadpole described by an investigator.

Typescript. / Bibliography: leaves 219-234. / x, 234 l illus

Proefschrift--Leiden. / "Samenvatting": p. 95-99. "Stellingen" ([2] p.) inserted. "Literature": p. 93-94.

Thesis (M.S.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The Rho GTPases are molecular switches principally known for their pivotal role in regulating the actin cytoskeleton throughout the phylogeny of eukaryotes. One major function for RhoA is regulation of the actin-myosin contractile apparatus in developing epithelia. Epithelial morphogenesis in Drosophila imaginal discs is regulated by RhoA signaling and the steroid hormone ecdysone. In order to learn more about the connection between ecdysone signaling and actin cytoskeletal dynamics during epithelial morphogenesis I have characterized mutations in 5 genes [designated en(zip)] that interact genetically with mutations in the Drosophila genes encoding myosin, RhoA, and an ecdysone-induced type II transmembrane serine protease required for epithelial morphogenesis. Two of the en(zip) mutations have been previously identified as alleles of RhoA and DRhoGEF2, two members of the RhoA signaling pathway. I have employed genetic complementation assays to characterize the three unidentified en(zip) genes and narrowed the putative location of two of these genes (18-5 and 31-6) to two small genomic regions. To further characterize the en(zip) mutants I have also determined the developmental lethal phase for each homozygous mutant. Homozygous RhoA 12 - 6 and DRhoGEF212 - 3 animals die during embryogenesis. In contrast, the en(zip) mutants 12-5, 31-6, and 18-5 are pupal lethals, suggesting that the primary role of their gene products may be to regulate epithelial morphogenesis during pupal development.