title: Equine zona protein synthesis and ZP structure during folliculogenesis, oocyte maturation, and embryogenesis.
abstract: In the equine, the zona pellucida (ZP) is the major barrier to successful in vitro fertilization. Therefore the aim of our studies was to analyze species-specific features of the equine ZP in regard to structure and glycoprotein ZPB and ZPC expression sites during oocyte development and embryogenesis. The equine ZP revealed high immunological cross-reactivity to porcine ZPB and ZPC. In the ovary, the distribution of ZPB and ZPC was co-localized and correlated with the developmental stage of the follicle. ZPB and ZPC expression started in the oocyte of the late primordial and primary follicle. In the secondary follicle, both the oocyte and the cumulus cells contributed to ZPB and ZPC synthesis. After in vivo maturation the oocyte stopped ZPB and ZPC production whereas the cumulus cells continued synthesis. Contrary, in vitro matured (IVM) cumulus-oocyte-complexes (COCs) revealed a reverse expression pattern. This was correlated to alterations in the distribution, number, and size of pores in the ZP. In the zona, N-acetylglucosamine residues were co-localized with ZPC. The acellular glycoprotein capsule surrounding early equine embryos was negative for ZPB and ZPC. Our results imply that in the horse ZPB and ZPC glycoprotein expression is differentially regulated during folliculogenesis, oocyte maturation, and embryogenesis. Contrary to the bovine and porcine, zona protein synthesis during in vivo maturation is completely overtaken by the cumulus cells implying that in the horse these cells are crucial for zona integrity. During IVM, the cumulus cells lose their ability to synthesize glycoproteins leading to alterations in the zona structure.
authors.affiliation: Institute of Veterinary Anatomy, University of Giessen, Giessen, Germany. sabine.koelle@vetmed.uni-giessen.de
authors.forename: Sabine
authors.initials: S
authors.lastname: Kölle
authors.forename: Clotilde S
authors.initials: CS
authors.lastname: Dubois
authors.forename: Maud
authors.initials: M
authors.lastname: Caillaud
authors.forename: Cécile
authors.initials: C
authors.lastname: Lahuec
authors.forename: Fred
authors.initials: F
authors.lastname: Sinowatz
authors.forename: Ghylène
authors.initials: G
authors.lastname: Goudet
mesh_terms: D000818:Animals; D002417:Cattle; D004527:Egg Proteins / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D006736:Horses; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D010053:Ovary / Q000166:cytology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013552:Swine; D015044:Zona Pellucida / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D000072216:Zona Pellucida Glycoproteins
chemical_list: D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins