spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

Right arrow Help viewing high resolution images
Right arrow Return to article
(Downloading may take up to 30 seconds.
If the slide opens in your browser, select File -> Save As to save it.)
Click on image to view larger version.


Figure 1


Fig. 1. MPF and CSF are key activities in vertebrate oocytes. The upper panel summarizes stages important for oocyte development and the onset of embryonic development. Oogenesis leads to the production of an immature oocyte arrested in prophase of meiosis I. After resumption of meiosis in response to hormonal stimulation, the oocyte progresses until the second arrest point in meiosis II (CSF arrest). Fertilization releases the oocyte from this arrest and triggers exit from meiosis II. The lower panel shows a simplified scheme illustrating the cytoplasmic injection experiments that led to the identification of MPF and CSF in frog oocytes. Small amounts of cytoplasm taken from mature oocytes were injected into immature oocytes or one blastomere of two-cell embryos. After injection immature oocytes resume meiosis whereas injected blastomeres arrest in metaphase. These observations led Masui and Markert to postulate that cytoplasm of mature oocytes contains two distinct biochemical activities, MPF and CSF, that regulate the oocyte maturation process (Masui and Markert, 1971).





Right arrow Return to article