Application of complementary DNA microarray (DNA chip) technology in the study of gene expression profiles during folliculogenesis

Objective: Using oligonucleotide microarray (DNA chip)–based hybridization analysis to gain a comprehensive view of gene expression and regulation involved in folliculogenesis. Design: Prospective randomized study. Setting: Academic institution. Animal(s): B6D2F1 female mice. Intervention(s): Superovulation. Main Outcome Measure(s): Preantral follicles isolated from day 14 B6D2F-1 mice were stimulated in vitro to form Graafian follicles. Total RNA extracted from the mouse preantral and Graafian follicles were reverse transcribed, labeled with digoxigenin-11-dUTP, and then hybridized with Clontech Atlas mouse cDNA expression arrays for comparison. Result(s): Of 588 known studied genes, 39 and 61 were detected in preantral follicles and in Graafian follicles, respectively, and 17 were highly expressed consistently in both preantral and Graafian follicles. Performing clustering analysis, we found that 15 detected genes were down-regulated and 46 were up-regulated as the follicles advanced to mature stages. Conclusion(s): We have successfully developed a sensitive DNA chip technology that is able to simultaneously and quantitatively study gene expression profiles in a small number of follicles (1.5–15 follicles). Several folliculogenesis-related genes have been identified. Some of these genes were expressed, indicating that they may be essential for follicle growth and maturation, whereas others were up-regulated only during late follicular development, indicating stage-specific roles.