Primordial and pre-antral follicles are not commonly observed in IVF aspirates

Follicular fluid recovered from IVF patients has been proposed to be a valuable source of pre-antral and primary follicles for patient therapy and research. We evaluated the recovery of immature follicles in follicular fluid from 54 patients undergoing IVF using several techniques.

Fluid from each patient underwent several methods of follicle recovery including: filtration through a cell strainer, Ficoll-Paque density gradient, isolate density gradient, histological slide preparation, and enzymatic digestion with collagenase and DNase.

34 primordial and primary follicles, mean 0.63 +/- 0.27/patient, and 14 pre-antral follicles, mean 0.26 +/- 0.14/patient, were found in this study. The serum estradiol level on the day of HCG injection was significantly lower (P < 0.05) in patients in which immature follicles were recovered, compared with those without immature follicles in the follicular fluid (1779.9 +/- 167.6 versus 2246.6 +/- 153.2 pg/ml). There were no women with advanced maternal age (>39 years) who had immature follicles in the follicular fluid.

Follicular fluid cannot be considered an efficient or reliable source of immature follicles. The presence of any immature follicles appears to be associated with cause of infertility, the random placement of the aspirating needle and may be related to the age of patient.