Biosynthesis of the canine zona pellucida requires the integrated participation of both oocytes and granulosa cells.
In the dog, attempts to localize the expression of zona pellucida (ZP) proteins during folliculogenesis have failed to demonstrate conclusively whether any or all of the zona proteins are synthesized in the oocyte or the granulosa cells. Probing of paraformaldehyde-fixed prepubertal canine ovarian tissue sections with a panel of fluorescently conjugated lectins localized the expression of glycoproteins during folliculogenesis. We confirm that six lectins (PSA, s-WGA, ECL, GSL-II, LEL, and STL) consistently labeled the ZP and adjacent granulosa cells of the developing follicle and that canine ZP expresses beta-gal(1,4)glcNAc, beta-gal(1,3)galNac, alpha-mannose, and terminal sialic acid residues in a developmentally specific manner. Riboprobes for canine ZPA and ZPC genes were produced and used for in situ hybridization studies of mRNA expression in canine folliculogenesis. In addition, we isolated a partial cDNA transcript from total ovarian RNA for the canine ZPB gene having a high degree of sequence identity with the felid and porcine ZPB homologues. Subsequently, the ZPA gene transcripts were localized to the cytoplasm of oocytes in primordial, primary, and early secondary follicles. We then localized expression of ZPB and ZPC gene transcripts to the granulosa cells of growing follicles, but not in squamous granulosa cells of primordial follicles or oocytes. These observations indicate that in the juvenile canine ovary, the oocyte is responsible for synthesis of the ZPA protein and directing synthesis of the ZPB and ZPC proteins by the granulosa cells and that ZP gene transcription occurs in a sequential manner during folliculogenesis.
Blackmore
Daniel G
DG
Reproductive Science Group, Discipline of Biological Sciences, School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia.
Baillie
Lucan R
LR
Holt
Janet E
JE
Dierkx
Lynda
L
Aitken
R John
RJ
McLaughlin
Eileen A
EA
D000367:Age Factors; D000818:Animals; D004285:Dogs; D004527:Egg Proteins / Q000235:genetics; D005260:Female; D006107:Granulosa Cells / Q000502:physiology*; D037102:Lectins; D008562:Membrane Glycoproteins / Q000235:genetics; D009865:Oocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000235:genetics; D012741:Sexual Maturation; D015044:Zona Pellucida / Q000502:physiology*; D000072216:Zona Pellucida Glycoproteins
D004527:Egg Proteins; D037102:Lectins; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins