Immunolocalization of zona pellucida antigens in the ovarian follicle of dogs, cats, horses and elephants

A comparative evaluation of the location of immunoreactive porcine zona pel lucida (pZP) glycoproteins was performed with polyclonal rabbit anti-pZP an tibodies on ovarian sections of the dog, cat, horse, and elephant. For this , formalin (light microscopy) and glutaraldehyde (transmission electron mic roscopy [TEM]) fixed ovarian sections were incubated with antibodies raised against highly purified pZP. Staining patterns were determined with diamin obenzidine (DAB) at the light level. The dog ZP had a distinct staining dis tribution that is characterized by intense staining around the periphery of the ZP and the oolemma and less dense staining throughout the width of the ZP. In dog follicles that contained multiple oocytes, there were oocytes o f identical and dissimilar stages. Cat ovarian sections showed uniform stai ning of the ZP. Horse results showed uniform staining of ZP and ooplasm, an d granulosa cells (GC). Elephant sections showed staining of the ZP with de nse staining at the oolemma, as well as staining of the ooplasm. In all spe cies the staining of the ZP was not evident until GC differentiation. In al l cases there was no staining of ovarian tissue with control normal rabbit serum. Specific staining patterns of ZP were evaluated by TEM and immunogol d staining. The immunogold-linked anti-pZP antibodies stained the ZP matrix in all species. There was staining of ooplasm organelles suggesting that Z P secretion originates from the oocyte of the dog and cat. In addition, fol licular and ZP measurements were taken that allowed accurate characterizati on of follicle stage. These findings suggest that in all four species the Z P is recognized by anti-pZP antibodies and there is also evidence to sugges t the possible origins of ZP glycoproteins. (C) 2001 by Elsevier Science In c.