Submitted February 28, 2007
Returned for revision March 28, 2007
Accepted April 26, 2007
Ovary
Relationships of Follicle Versus Oocyte Maturity to Ultrasound Morphology, Blood Flow, and Hormone Concentrations of the Preovulatory Follicle in Mares
O. J. Ginther *,
E. L. Gastal ,
M. O. Gastal ,
M.A.R. Siddiqui ,
and
M. A. Beg
* To whom correspondence should be addressed. E-mail: ginther{at}svm.vetmed.wisc.edu.
Abstract
The effects of ultrasound morphology, vascularity, and follicular-fluid hormones of the preovulatory follicle on oocyte recovery rate and on follicle and oocyte maturity rates were studied for 60 spontaneous and solitary preovulatory follicles in mares. An ovulation-inducing dose of hCG was given when the follicle was 
32 mm (Hour 0), and a procedure for oocyte recovery was done 30 h later (Hour 30). Between Hours 0 and 30, diameter of the follicle increased less and circulating estradiol concentrations decreased more in groups with successful versus nonsuccessful oocyte recovery and in groups with mature versus immature recovered oocytes, as indicated by significant interactions of group and hour. Significant differences in blood-flow end points between groups were not detected. At Hour 30, the frequency of granulosa serration, an indicator of impending ovulation, was higher (P < 0.001), and the number and expansion of granulosa cells in the lavaging fluid, indicators of follicle maturity, were greater in the oocyte-recovery group and in the oocyte-mature group. Follicular-fluid concentrations of estradiol, progesterone, and free insulin-like growth factor (IGF)1 were not different between the oocyte-recovery and nonrecovery groups. Concentrations of estradiol and progesterone were significantly greater and free IGF1 was significantly lesser in the oocyte-mature than in the immature groups. Results indicated that the post-hCG oocyte-recovery and oocyte-maturity rates were positively affected by follicle maturity. Greater follicular-fluid estradiol and progesterone concentrations were associated temporally with maturation of the oocyte but not with maturation of the follicle, and greater free IGF1 concentration was associated with oocyte immaturity.
Key words:
Apoptosis •
Follicle •
Growth factors •
Oocyte development •
Steroid hormones
