PARENT SESSION
PLATFORM SESSION 7. EMBRYOGENESIS AND FERTILIZATION

Sunday, August 1, 2004
3:00 PM–5:00 PM
Buchanan A102
Chair: David Puett Co-Chair: Jennifer Weck

(56) INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN AS PREDICTIVE MARKERS FOR DEVELOPMENTALLY COMPETENT OOCYTES.

Nicholas, Benjamin¹, Alberio, Ramiro¹, Fouladi-Nashta, Ali¹, Webb, Robert¹, ¹ The University of Nottinghan, Loughborough, UK

ABSTRACT- Bovine follicular atresia is characterized by the apoptosis of granulosa cells and loss of oocyte competence. A range of factors, including components of the IGF system and the caspase enzyme system are involved in follicular atresia. While the IGFBPs are present throughout follicular development, IGFBP-5 is present only during atresia. Here we investigated whether there is a correlation between follicular atresia, IGFBP-5 content in the follicular fluid, caspase 3 activity and oocyte developmental competence. In Expt. 1, healthy dominant (>8mm), subordinate 1 (S1; 6-8mm) and subordinate 2 (S2; <6mm) follicles were dissected from bovine ovaries 5 days after estrus synchronization. IGFBP-5 was measured in follicular fluid and granulosa cell homogenates were analyzed for caspase 3 activity. Caspase 3 activity and IGFBP-5 were undetectable in healthy dominant follicles, whereas increasing levels of both components were measured in S1 and S2 follicles. There was a highly significant (p<0.001) correlation between the two parameters. Similar results were obtained from follicles of non-synchronised animals. In Expt. 2, oocytes were collected from 4-8mm follicles derived from abattoir derived ovaries and were individually matured for 24h, during which the follicular fluid and granulosa cells from each individual follicle was analyzed for IGFBP-5 and caspase-3 activity, respectively. After IVM oocytes were grouped on the basis of IGFBP-5 levels (A-low, B-medium, C-high) and fertilized in vitro. Significantly (P<0.05) higher development to the blastocyst stage (18.3%) was obtained from group B oocytes in contrast to both group A (8.3%) and group C (4.6%) oocytes. Oocytes from group A produced significantly more blastocysts than group C (p<0.05). In conclusion these results indicate that IGFBP-5 in follicular fluid, and caspase 3 activity in granulosa cells can be used as effective non-invasive predictors of oocyte developmental competence.

KEY WORDS: Caspase 3, development, IGFBP-5, oocyte