LIGHT MICROSCOPE INVESTIGATION ON MEIOTIC CHROMOSOME PAIRING IN ARTIFICIAL TKIPLOID FISHS WITH B LOCKED OVARIES

Chromosome pairing was light microscopically investigated by applying surfacespreading technique in combination with 1-step silver staining method for the pa-chvtene chromosome of artificial triploid transparent colored crucian carp(Carassiusauratus transparent colored variety)with blocked ovaries.The triploid fishes wereproduced from hydrostatic pressure shock for fertilized eggs by inducing second po- lar body retention. The study was performed on the triploid females with blockedovaries,one of manv different types of females with various developing ovaries.Twosubtypes were distinguished according to the presence or absence of primary oocytes. Meiotic prophase cells were not observed in the triploid females without pri-mary oocytes.In the triplold females with blocked ovaries containing differentiatedprimary oocytes,the pachytene chromosomes were mainly composed of bivalents andunsynapsed univalents,and a few of trivalents and other multivalents were alsofound.There are about 90 chromosome elements including univalents,bivalents,tri-valents and other multivalents in the pachytene cells.The size of chromosomesamong diffrent pachytene cells was obviously various.The pairing forks and speci- fic synaptonemal proteins were clearly observed at some pairing and paired chromo-somes.The relationship between disturbed chromosome pairing and blocked oocytedeveloping has been briefly discussed. The investigation also suggested that the arti-ficial triploid fishes might be excellent materials for studying the mechanism ofchromosome pairing and synapsing.