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ID 32932
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Author
Kikuchi, Kazuhiro
Ekwall, Hans
Tienthai, Paisan
Kawai, Yasuhiro
Noguchi, Junko
Kaneko, Hiroyuki
Rpdriguez-Martinez, Heriberto
Abstract

Lipid content in mammalian oocytes or embryos differs among species, with bovine and porcine oocytes and embryos showing large cytoplasmic droplets. These droplets are considered to play important roles in energy metabolism during oocyte maturation, fertilisation and early embryonic development, and also in the freezing ability of oocytes or embryos; however, their detailed distribution or function is not well understood. In the present study, changes in the distribution and morphology of porcine lipid droplets during in vivo and in vitro fertilisation, in contrast to parthenogenetic oocyte activation, as well as during their development to blastocyst stage, were evaluated by transmission electron microscopy (TEM). The analysis of semi-thin and ultra-thin sections by TEM showed conspicuous, large, electron-dense lipid droplets, sometimes associated with mitochondrial aggregates in the oocytes, irrespective of whether the oocytes had been matured in vivo or in vitro. Immediately after sperm penetration, the electron density of the lipid droplets was lost in both the in vivo and in vitro oocytes, the reduction being most evident in the oocytes developed in vitro. Density was restored in the pronculear oocytes, fully in the in vivo specimens but only partially in the in vitro ones. The number and size of the droplets seemed, however, to have decreased. At 2- to 4-cell and blastocyst stages, the features of the lipid droplets were almost the same as those of pronuclear oocytes, showing a homogeneous or saturated density in the in vivo embryos but a marbled or partially saturated appearance in the in vitro embryos. In vitro matured oocytes undergoing parthenogenesis had lipid droplets that resembled those of fertilised oocytes until the pronuclear stage. Overall, results indicate variations in both the morphology and amount of cytoplasmic lipid droplets during porcine oocyte maturation, fertilisation and early embryo development as well as differences between in vivo and in vitro development, suggesting both different energy status during preimplantation development in pigs and substantial differences between in vitro and in vivo development.

Keywords
Culture
In vitro
In vivo
Lipid droplet
Pig
Note
Digital Object Identifier:10.1017/S0967199402004100
Published with permission from the copyright holder. This is the institute's copy, as published in Zygote, Nov 2002, Volume 10, Issue 4, Pages 355-366.
Publisher URL:http://dx.doi.org/10.1017/S0967199402004100
Direct access to Thomson Web of Science record
Copyright © 2002 Cambridge University Press. All rights reserved.
Published Date
2002-07-25
Publication Title
Zygote
Volume
volume10
Issue
issue4
Start Page
355
End Page
366
Content Type
Journal Article
language
英語
Refereed
True
DOI
Web of Sience KeyUT
Submission Path
agriculture_general/4