Effects of Injecting Calcium Chloride into in Vitro-Matured Porcine Oocytes1

Abstract

In vitro-matured porcine oocytes were given injections of 0.1 M CaCl2 and after 6 h evaluated for signs of early and late activation events. CaCl2 injection caused cortical granule exocytosis in 75% (3 of 4) of the oocytes tested. It also induced cell cycle resumption as monitored by the histone H1 kinase assay: the phosphorylation rate of histone H1 decreased to 36.7% of the original value. Treated oocytes completed meiosis, extruded the second polar body, and progressed to first interphase: 79.4% of them formed one or more pronuclei. The elevated intracellular Ca2+ level resulted in activation-related changes in the protein synthetic profile in 90% (9 of 10) of the oocytes. Furthermore, 14.7% (9 of 61) of the treated oocytes developed to the compact morula/early blastocyst stage after a 7-day culture in ligated porcine oviduct, and one blastocyst hatched from the zona pellucida. Control oocytes given injections of 0.1 M MgCl2 or carrier medium (10 mM Hepes) did not show the changes mentioned. The results strengthen the idea that Ca2+ is a cell messenger that plays a central part in oocyte activation; it is concluded that elevated intracellular Ca2+ level caused by a single injection of CaCl2 leads to both early and late events of porcine oocyte activation.

Activation and Development of Pig Oocytes after Microinjection of Crude Sperm Extract

“…The release of cortical granules is induced by the increased [Ca 2+ ] i caused by the spermatozoon. It is also induced by different treatments, such as electro-stimulation [7] and microinjection of Ca 2 + [9,10] in the pig, calcium ionophore in the hamster [1], and exposure to the medium containing Sr 2+ in the mouse [36]. In the present study, cortical granules were released within 6-8 h after electro-stimulation or microinjection of sperm extract, and the result was consistent with the previous report [11].…”

“…In the pig, an electro-stimulation technique [5] has been used for oocyte activation [6][7][8]. [9,10] and soluble sperm extract [11]. In many species studied so far, such as the hamster [12], mouse [13], human [14], cow [15] and pig [11], injection of sperm extract activates oocytes with repetitive increases in intracellular Ca Moreover, it has been reported that oocytes injected with sperm extract develop to blastocysts in the mouse [16], cow [16] and pig [11].…”

The role of nitric oxide in parthenogenetic activation of pig oocytes: A review

“…The sperm penetration is followed by the exocytosis of cortical granules within 6 hours (Yoshida et al, 1993). After parthenogenetic activation, the exocytosis of cortical granules was weaker than after the sperm penetration (Wang et al, 1998b), but many types of artificial activating stimuli are able to induce the exocytosis of cortical granules (Sun et al, 1992;Machatý et al, 1996Machatý et al, , 1997Okada et al, 2003). Cortical granule exocytosis followed very quickly after the activating stimulus .…”

Caffeine promotes premature chromosome condensation formation and in vitro development in porcine reconstructed embryos via a high level of maturation promoting factor activity during nuclear transfer

“…On the other hand, we found that microinjection decreased MPF activity in NT embryos. This effect of microinjection seems not to be a result of aging during handling mentioned as above, but rather the influx of Ca 2þ ions (Machaty et al 1996). The influx of Ca 2þ ions involved in microinjection could be avoided by performing manipulation in the Ca 2þ ion-free medium; however, maintenance of porcine oocytes in a nondegenerated state requires the presence of Ca 2þ ions in the medium (Bae & Channing 1985).…”