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This Article Full Text Full Text (PDF) All Versions of this Article: 70/5/1263    most recent biolreprod.103.022111v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal My Folders Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Huynh, K. Articles by Jones, M. E.E. Search for Related Content PubMed PubMed Citation Articles by Huynh, K. Articles by Jones, M. E.E. Agricola Articles by Huynh, K. Articles by Jones, M. E.E.

Estrogen Is Not Directly Required for Oocyte Developmental Competence¹

Department of Anatomy³ and Institute of Reproduction and Development,⁴ Monash University, Clayton, Victoria 3800, Australia Prince Henry's Institute of Medical Research,⁵ Clayton, Victoria 3168, Australia

Oocyte maturation and ovulation require a coordinated interaction between gonadotrophs, steroid hormones, and growth factors. The extent to which estrogen is required in this process, however, remains unclear. To better understand the role of estrogen in maintaining developmental competence of mammalian oocytes, we studied the Aromatase knockout (ArKO) mouse, which has been genetically engineered to be incapable of synthesizing endogenous estrogen. Previous studies have established that ArKO female mice are anovulatory with ovaries that progressively degenerate, developing hemorrhagic cystic follicles. In young ArKO females, however, apparently healthy follicles and oocytes have been observed. We investigated if these oocytes could be induced to ovulate, then mature, fertilize, and develop in vitro. Following a standard superovulation protocol, ArKO oocytes did not ovulate. When recovered manually from the ovary, however, ArKO oocytes successfully progressed through in vitro maturation, fertilization, and development to the blastocyst stage at the same rate as wild-type and heterozygote littermates. Therefore, it appears that estrogen is not required for the production and growth of oocytes capable of maturation and complete preimplantation development but is required for continued follicle growth and feedback regulation of ovulation.

¹ Supported in part by a National Health & Medical Research Council Project Grant (169010), a U.S. Public Health Service Grant (R37 AG- 08174), and a grant from the Victorian Breast Cancer Research Consortium, Inc.

² Correspondence: Margaret Jones, PHIMR, Level 4, Block E, 246 Clayton Road, Clayton VIC 3168, Australia. FAX: 61 3 9594 6376; Margaret.Jones{at}phimr.monash.edu.au

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