关键词: 江豚, 染色体, 核型

Abstract: The karyotype of finless porpoise (Neophocaena phocaenoides) has been determined in the bone marrow cells of the sternum by the colchicine-hypot-onic-fire drying technique.This is the first report of the karyotype of finless porpoise.The diploids of chromosomes amount to 44 (2 n = 44) .They may be classified into four groups and one pair of sex chromosomes.Group A consists of 5 metacentric chromosome pairs; group B has 9 sub-metacentric chromosome pairs5 group C has 2 sub-acrocentric chromosome pairs which are largest among all chromosome pairs; group D has 5 pairs of acrocentric chromosomes. The last pair of group D is smallest among the autosomes.Sex chromosomes are of X, Y type.The X chromesome is metacentric and is similar in size to the first pair of group D and the fourth pair of group B.The Y chromosome is a minute element and can be identified as acrocentric in favorable preparations.The karyotype of finless porpoise is different from those of harbour porpoise (Phocoena phocoena) and of Dall's porpoise (Phocoenoides dalli) as shown in Table 2 .

Key words: Finless porpoise, Neophocaena phocaenoides, Choromosome, Karyotype