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George W. Piavis

Publications and source records attributed to George W. Piavis.

5 recordsLinked to original sources
USGS1971

Blood cell lineage in the sea lamprey, Petromyzon marinus (Pisces: Petromyzontidae)

Blood cell types of the sea lamprey, Petromyzon marinus , are described and identified and the lineage of mature circulating cells in peripheral blood is traced to blast cells in the hematopoietic fat body. The fat body appears to be the phylogenetic precursor of bone marrow in higher forms, since blood cells originate and begin maturation in this tissue. Experimental animals were injected first with a hematopoietic stimulant and then (at an experimentally determined time) with pertussis vaccine to release proliferated blood cells into peripheral blood. Peripheral blood for smears was collected by cardiac exsanguination; hematopoietic tissue was extirpated for imprints; and leucocyte preparations were made by a special technique. Blood cells of the sea lamprey are apparently products of at least four distinct blast cells, each of which has a 'one end' maturation process. Results of this investigation support the polyphyletic theory of blood cell formation.

Copeia↗
USGS1970

Experimental hybridization among five species of lampreys from the Great Lakes

Experimental hybridization among five species of lampreys of the Upper Great Lakes routinely produced embryos through stage 8, and four crosses produced embryos to the larval stage. Three critical periods in the embryogenesis of hybrid lampreys were between stages 8 and 9, among stages 10, 11, and 12, and at stage 15. Embryonic development in hybrid lamprey embryos is basically identical to that of controls and is identical to that of the sea lamprey (Petromyzon marinus). Synchrony of development was observed among stages of viable hybrids and their controls but lethal hybrids generally did not maintain such synchrony. The derivative species concept has been confirmed experimentally. Questions have been raised concerning some evidence cited in behalf of the appropriateness of the concept that nonparasitic lampreys are the derived species.

Copeia↗
USGS1969

Rearing of sea lamprey, Petromyzon marinus, embryos in distilled water

Most embryological studies of lampreys in the Great Lakes have been conducted with filtered water from Lake Huron. Although this water was entirely satisfactory for the earlier work, the present need for knowledge of the effects of various compounds on embryological development requires that the initial medium be sterile. The purpose of the present study was to determine whether sea lamprey embryos could be successfully reared in distilled water. Mature sea lampreys were collected from the Ocqueoc River, Presque Isle County, Michigan, and transferred to the Hammond Bay Biological Station where eggs were stripped and fertilized according to the method of Piavis. After activation was ascertained to be 90-100% complete, the embryos were washed 3-5 timesexperimentals with commercially obtained U.S.P. distilled water and controls with filtered Lake Huron water.

Copeia↗