Effects of follicle size and electrolytes and glucose in maturation medium on nuclear maturation and developmental competence of bovine oocytes

Abstract

The concentrations of electrolytes (Na, K, Cl, Mg and Ca) and glucose in small follicle (SF) follicular fluid (SFF) and large follicle (LF) follicular fluid (LFF) from slaughterhouse-derived ovaries were studied. Oocytes were matured in medium based on synthetic oviductal fluid. The effects of various concentrations of electrolytes (Na, K, Ca and Mg) and glucose in the maturation medium on the progression of nuclear maturation and subsequent development were also studied. K in SFF was significantly greater than that in LFF. The Mg concentration in follicular fluid (FF) is 2.0 -2.3 mM, which is greater than the concentration present in medium generally used for culture. The glucose concentration in FF is about 3.5 -3.9 mM and rapidly decreases during the preservation of ovaries. LF oocytes resumed nuclear maturation and progressed to the M2 stage significantly faster than those collected from SF oocytes. In addition, more LF oocytes developed to blastocysts than did SF oocytes. Changing the Na/K ratio in the maturation medium from 16 to 24 did not affect either the progression of nuclear maturation or the rate of development. A low concentration of Mg (0.5 mM) combined with a low Ca concentration (0.5 mM) inhibited the rate of development, but did not affect the progression of nuclear maturation. On the other hand, increasing the Mg concentration to 2.0 mM from 0.5 mM hastened the progression of nuclear maturation and improved the rate of blastulation, irrespective of the Ca concentration. The progression of nuclear maturation was faster and the rate of development was greater with 5.56 mM glucose than with 1.5 mM glucose. The difference in time needed to progress to M2 among the experiment was about 2-3 h. Therefore, prolonging the maturation periods from 21 to 24 h did not change the rate of development. Our results show that the concentrations of Mg and glucose in the maturation medium and the follicle size enveloping the oocyte affect the progression of nuclear maturation and subsequent development. The time requirement for oocytes to reach M2 is strongly related to the developmental competence of the oocytes.

Study the Effects of Follicular Size on some Biochemical Follicular Fluid Composition in She Camel (Camelus Dromedarius)

“…However, this process requires osmosis process across cell wall that increase with the elevation of sodium ions in the large follicle (Sharma et al, 1995). The results of the present study are agreed with previous studies in camels (Al Fattah et al, 2012), cattle (Iwata et al, 2004), buffalo (Kaur et al,1997), goats (Bordoloi et al, 2001) and sheep (Nandi et al, 2007). While, these results are incompatible with (Rabiee et al,1999) in cattle and(Arshad et al, 2005) in buffalo.…”

“…in the follicular fluid of the small and large follicles respectively. Calcium plays an important role in the production of lipid hormones of the developing follicles and it regulates the secretion of breeding hormones necessary for ovaries and ovulation (Iwata et al, 2004). Moreover, calcium ions isinvolved in the formations of estrogen.…”

Effects of green tea polyphenols, insulin-like growth factor I and glucose on developmental competence of bovine oocytes

“…The results of experiment 3 indicated that sufficient glucose is required for oocytes to obtain developmental competence during the maturation period. The beneficial effect of glucose supplementation in the IVM medium may be due to their ability to speed up the progression of nuclear maturation (Iwata et al, 2004). The results from this study also demonstrated that excessive glucose during oocyte maturation impairs the developmental competence.…”

Evaluation of laser-assisted lentiviral transgenesis in bovine

“…Previous studies demonstrated that within a period of 21 -24 h after the onset of maturation, the start of fertilization does not influence development to blastocyst (Iwata et al, 2004). Thus, it is unlikely that delayed fertilization was the reason for lower blastocyst rates in the oocyte treatment groups.…”