Strain-specific spontaneous activation during mouse oocyte maturation

Oocyte spontaneous activation, an irregularity of the cell cycle that can lead to ovarian teratomas, has genetic variation among inbred mouse strains, and is sensitive to the culture environment.

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Authors

Yong Cheng, Ph.D., Zhisheng Zhong, Ph.D., Keith E. Latham, Ph.D.

Vol 98, Issue 1 , Pages 200-206

Abstract

Objective:

To examine whether spontaneous oocyte activation is determined by genetic differences and interacts with culture environment.

Design:

Experimental study.

Setting:

Temple University School of Medicine.

Animal(s):

C57BL/6, DBA/2, C3H/HeJ, and A/J strains, along with reciprocal F1 hybrid female mice (5–6 weeks).

Intervention(s):

Immature oocytes from different mouse strains collected and cultured in different maturation conditions, including different serum, serum replacement, bovine serum albumin (BSA), and follicle-stimulation hormone (FSH).

Main Outcome Measure(s):

The emission of first polar body, pronucleus formation, meiotic arrest, spontaneous activation, and expression of maturation regulators.

Result(s):

Oocytes from C57BL/6 mice display a high rate of delayed first meiotic division and spontaneous activation after the first meiotic division with in vitro maturation (IVM), and the second meiotic division with in vivo maturation (VVM) after superovulation. Spontaneous activation with IVM is sensitive to culture environment. Oocytes that spontaneously activated during the first meiotic division with IVM have unusual replicated sister chromatid pairs with slight connections at centromeres at first mitosis, whereas oocytes that activated in vivo display haploidization from the second meiotic division. Spontaneous activation is also seen in F1 hybrid oocytes, indicating a dominant trait from C57BL/6. Delayed meiosis was associated with reduced cyclin B and securin expression.

Conclusion(s):

Both mouse strain and culture environment have a statistically significant effect on the incidence of meiotic defects and spontaneous activation. Reduced expression of meiotic regulators may underlie this effect.

Read the full text at: http://www.fertstert.org/article/S0015-0282(12)00440-2/fulltext


Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders. The journal publishes juried original scientific articles in clinical and laboratory research relevant to reproductive endocrinology, urology, andrology, physiology, immunology, genetics, contraception, and menopause. Fertility and Sterility® encourages and supports meaningful basic and clinical research, and facilitates and promotes excellence in professional education, in the field of reproductive medicine.

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