Androgenic Haploids of a Toad, Xenopus laevis

ترتیب اعصای جانبی در دم لارو of Xenopus laevis

Histogenesis of lymphoid organs in larvae of the South African clawed toad, Xenopus laevis (Daudin).

Before embarking on a study of the lymphoid system of an amphibian larva, it is necessary to realize that lymphoid tissue may occur in many organs of the body and that in all immature vertebrates and in adult poikilotherms separation of lymphoid tissue from myeloid tissue is incomplete (Yoffey, 1960). Jordan (1938) reviewed the early work on the haemopoietic tissues of Amphibia. Cooper (1967tf,...

Specification of retinotectal connexions during development of the toad Xenopus laevis.

The specification of central connexions of retinal ganglion cells was studied in Xenopus laevis. In one series of experiments, the right eye primordium was rotated 180 degrees at embryonic stages 24-32. In the other series, the left eye was transplanted into the right orbit, and vice versa, with either 0 degrees or 180 degrees rotation. After metamorphosis the visual projections from the operat...

An ultrastructural and radioautographic study of early oogenesis in the toad Xenopus laevis.

Early oogenesis in the toad Xenopus laevis has been investigated at the ultrastructural level, with particular reference to the formation of extrachromosomal DNA. Thymidine incorporation was localized by electron microscope radioautography. In oogonia, the nucleus is irregular in outline and may contain several nucleoli. Oocytes, from premeiotic interphase to late pachytene, are found in cell n...

The Timing of Meiosis and Dna Synthesis during Early Oogenesis in the Toad, Xenopus Laevis

Recently metamorphosed female Xenopus laevis toads were injected with tritiated thymidine. Animals were kept at 20 degrees C and were sacrificed 1-23 days after isotope injection. Radio-autographs of squash preparations of the ovaries were made. The progress of labeled germ cell nuclei was followed to obtain information on the time course of early meiosis and extra-chromosomal DNA synthesis. Pr...