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Effects of cryodevice type and donors' sexual maturity on vitrification of minke whale (Balaenoptera bonaerensis) oocytes at germinal vesicle stage

Published online by Cambridge University Press:  04 February 2005

Hiroshi Iwayama
Affiliation:
Laboratory of Animal Reproduction, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
Shinichi Hochi
Affiliation:
Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.
Megumi Kato
Affiliation:
National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan.
Masumi Hirabayashi
Affiliation:
National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan.
Masashige Kuwayama
Affiliation:
Kato Ladies Clinic, Tokyo 160-0023, Japan.
Hajime Ishikawa
Affiliation:
The Institute of Cetacean Research, Tokyo 104-0055, Japan.
Seiji Ohsumi
Affiliation:
The Institute of Cetacean Research, Tokyo 104-0055, Japan.
Yutaka Fukui
Affiliation:
Laboratory of Animal Reproduction, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.

Abstract

Germinal-vesicle-stage oocytes enclosed with compact cumulus cell layers (COCs) were recovered from adult or prepubertal minke whale ovaries, and were vitrified in a solution containing 15% ethylene glycol, 15% DMSO and 0.5 M sucrose using either a Cryotop or an open-pulled straw (OPS) as the cryodevice. The post-warm COCs with normal morphology were cultured for 40 h in a 390 mosmol in vitro maturation medium, and oocytes extruding the first polar body were considered to be matured. The proportion of morphologically normal COCs after vitrification and warming was higher when the COCs were cryopreserved by Cryotop (adult origin, 88.4%; prepubertal origin, 80.8%) compared with the OPS (adult origin, 67.7%; prepubertal origin, 64.2%). The oocyte maturation rate was higher in the adult/Cryotop group (29.1%) compared with those of the prepubertal/Cryotop group (14.4%), the adult/OPS group (14.3%) and the prepubertal/OPS group (10.6%). These results indicate that the Cryotop is a better device than the OPS for vitrification of immature oocytes from adult minke whales.

Type
Research Article
Copyright
2004 Cambridge University Press

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