Prolonged, repetitive calcium transients in rat oocytes fertilized in vitro and in vivo.
Zona-free rat oocytes inseminated with capacitated sperm, under conditions that allow polyspermic fertilization, exhibited a rapid, transient elevation of cellular calcium (from 147 +/- 10 to 607 +/- 55 nM, n = 19, measured by Fura 2 fluorescence ratio imaging) immediately after sperm attachment. This peak was followed by a series of dramatic calcium transients of high amplitude (maximal 847 +/- 32 nM) and frequency (range 2.1 +/- 0.07 - 3.9 +/- 0.07 min), which continued for several hours. A similar pattern was seen also in zona-free oocytes fertilized with low sperm density (i.e. producing mainly monospermic attachment) and in zona-enclosed oocytes fertilized in vitro. Moreover, single or repetitive calcium transients were observed in rat oocytes fertilized in vivo. These findings indicate that in normal fertilization in vivo, sperm-oocyte interaction initiates a prolonged train of cyclical calcium changes in the oocyte. This activity may be necessary for the early events in the fertilization process.
Department of Embryology, Sackler Faculty of Medicine, Tel Aviv University Ramat Aviv, Israel.
D
D
Ben-Yosef
Y
Y
Oron
R
R
Shalgi
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D066298:In Vitro Techniques; D008297:Male; D009865:Oocytes / Q000378:metabolism*; D051381:Rats; D013084:Sperm-Ovum Interactions; D013997:Time Factors
D015220:Calcium Channels; D002118:Calcium