The comprehensive mechanisms underlying nonhierarchical follicular development in geese (Anser cygnoides)

The laying performance of poultry primarily depends on the growth and development of the ovarian follicles. Yet, little is known about the underlying mechanisms responsible for nonhierarchical follicular development in avian species. The aim of the present study is identify genes that are differentially expressed during nonhierarchical follicular development in geese by performing a transcriptome screen. A sequencing depth of 13.9 and 14.9 million mapped tags was obtained in pools of small white follicles (SWF) and small yellow follicles (SYF), respectively, and a total of 160 differentially expressed genes were identified. The fold-changes of eight differentially expressed genes, identified using qRT-PCR, were consistent with the Digital Gene Expression Profiling (DGE) data. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) analyses showed that lipid metabolism, steroid secretion, extracellular ligand reactions, enzyme activities, the cell cycle, ECM-receptor interactions and the extracellular matrix are involved in follicular development. The majority of the newly identified genes could be considered to be new candidate genes with potential roles in regulating follicular development. These results provide useful information for future in-depth studies associated with nonhierarchical follicular development in goose reproduction.