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.
Ben-Yosef
D
D
Department of Embryology, Sackler Faculty of Medicine, Tel Aviv University Ramat Aviv, Israel.
Oron
Y
Y
Shalgi
R
R
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