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Background: For the past more than 25 years, we have been focusing on the developmental and reproductive biology of the female gametes, oocytes, and eggs, of the African clawed frog Xenopus laevis.
Methods: The events associated with the life cycle of these cells can be classified into the four main categories: first, oogenesis and cell growth in the ovary during the first meiotic arrest; second, maturation and ovulation that occur simultaneously and result in the acquisition of fertilization competence and the second meiotic arrest; third, fertilization, that is sperm-induced transition from egg to zygote; and fourth, egg death after spontaneous activation in the absence of fertilizing sperm.
Main findings: Our studies have demonstrated that signal transduction system involving tyrosine kinase Src and other oocyte/egg membrane-associated molecules such as uroplakin III and some other cytoplasmic proteins such as mitogen-activated protein kinase (MAPK) play important roles for successful ovulation, maturation, fertilization, and initiation of embryonic development.
Conclusion: We summarize recent advances in understanding cellular and molecular mechanisms underlying life cycle events of the oocytes and eggs. Our further intention is to discuss and predict potentially promising impact of the recent findings on the challenges facing reproductive biology and medicine, as well as societal contexts.
Figure 1- Life cycle events of oocytes and eggs in Xenopus laevis: from its cradle (oogenesis in ovary) through ovulation and maturation to physiological (sperm‐dependent initiation of zygotic development, ie, fertilization) or pathological ending (spontaneous activation‐mediated death by apoptosis or overactivation)
Figure 1. Life cycle events of oocytes and eggs in Xenopus laevis: from its cradle (oogenesis in ovary) through ovulation and maturation to physiological (sperm‐dependent initiation of zygotic development, ie, fertilization) or pathological ending (spontaneous activation‐mediated death by apoptosis or overactivation)
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