The sugar chains in cellular glycoconjugates have many biological functions. Extensive morphological development and remodeling occurs in the ovaries. The aim of the study is to investigate glycobiological characteristics of ovarian cells, particularly granulosa cells that undergo apoptosis during follicular atresia.

Changes of glycoconjugates in granulosa cells during follicular atresia of the pig ovaries were examined by lectin histochemical and blot analysis combining glycosidase treatment, and RT-PCR analysis for ST6Gal I mRNA.

Three lectins (SSA, AAL and PSA: specific for Sia2,6Gal/GalNAc, -L-fucose and L–Fuc1,6GlcNAc, respectively) showed increased reactivity for granulosa cells in atretic follicles relative to those in healthy follicles. Especially, SSA showed positive staining for granulosa cells only in atretic follicles by lectin histochemistry. Lectin blot analysis for SSA demonstrated specific glycoproteins only in atretic follicles. Most of SSA–positive glycans were Sia2,6Gal1,4GlcNAc on complex–type N–glycans, suggesting that only ST6Gal I, one of four 2,6–sialyltransferases, catalyzes. RT–PCR analysis demonstrated that the expression of ST6Gal I mRNA was up–regulated in granulosa cells during atresia.