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.
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/175206 |
| Date | January 1977 |
| Creators | Branham, Arthur E. |
| Contributors | List, James C. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | v, 54 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
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