Fertility of Triploid Backcross Progeny,(Gengoroubuna Carassius auratus cuvieri .FEMALE.Carp Cyprinus carpio .MALE.)F1.FEMALE.Carp or Gengoroubuna .MALE..

概要

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The fertility of triploid backcross progeny, (gengoroubuna Carassius auratus cuvieri _??_ ×carp Cyprinus carpio _??_) F1 _??_ ×gengoroubuna or carp_??_ is reported . In females, spawning could be induced by the injection of pituitary extracts. The fertilization rates were from 52 .4 to 88.6%, and free swimming rates from 2.6 to 34.4%. Many normal larvae were obtained after crossing with the sperm of gengorou -buna. However, after crossing with sperm of the loach Misgurnus anguillicaudatus, most of the embryos died before hatching and no normal larvae were obtained. Sperm could not be stripped from the progeny of either type of triploid backcross after the injection of pituitary extracts. Under light microscope, each seminal lobule in the testis was mainly occupied by spermatocytes in various stages. Some spermatids were found in part of the lobules, but no spermatozoa were observed. These facts suggest that the laboratory-reared, triploid backcross progeny may represent an intermediate step in the evolution of a gynogenetic triploid form.
日本魚類学会の論文