Zona Reaction in Porcine Oocytes Fertilized In Vivo and In Vitro as Seen with Scanning Electron Microscopy1

Abstract

Morphological changes in zona pellucidae (ZP) isolated from in vitro-matured (IVM) and ovulated porcine oocytes were compared before or after fertilization in vitro and in vivo, respectively, by using scanning electron microscopy (SEM). The ZP of some ovulated or IVM oocytes and in vivo- or in vitro-fertilized (IVF) zygotes were equally split into two halves while immersed in an enzyme-inhibitor solution, using a surgical blade. After washing, intact and ZP halves were fixed in 1% glutaraldehyde solution in 0.1 M cacodylate buffer, processed, and examined using SEM. The outer surface of ZP in ovulated oocytes had a mesh-like structure. The outer morphology in IVM oocytes was more smooth although the mesh-like structure was still visible at high magnification. In in vivo zygotes and IVM-IVF zygotes, this lysed, mesh-like structure was more obvious. The inner surface of ZP had some small depressions (orifices). The mean number of orifices per 100 micrometer(2) of ZP surface was larger in IVM oocytes as compared to ovulated ones. The number of orifices per 100 micrometer(2) decreased in IVM-IVF zygotes as compared to IVM oocytes; whereas, in vivo zygotes did not differ from ovulated oocytes. The mean diameter of intact ZP as well as their mean thickness was greater in ovulated oocytes than IVM oocytes. The mean thickness of the ZP was larger in ovulated oocytes than IVM ones. The ZP thickness was larger in zygotes than in in vivo oocytes, whereas that of IVM-IVF zygotes did not differ from that of IVM oocytes. These results indicate that the morphology of ZP and the ZP reaction at sperm penetration appears to be much different between IVM oocytes and ovulated ones.

A hybrid characterization framework to determine the visco-hyperelastic properties of a porcine zona pellucida

“…As the ZP membrane is much softer than the AFM probe, the indenter was modelled as a rigid blunt cone with a tip radius of 10 nm and an angle of aperture of 408. The ZP membrane was instead modelled as an incompressible visco-hyperelastic slab, 30 mm long rsfs.royalsocietypublishing.org Interface Focus 4: 20130066 and 6 mm thick (the value of thickness is consistent with data reported in [22] for porcine oocytes). The FE model simulating the AFM nanoindentation process is shown in figure 1.…”

Reduction of the incidence of polyspermic penetration into porcine oocytes by pretreatment of fresh spermatozoa with adenosine and a transient co-incubation of the gametes with caffeine

“…Although treatments affecting sperm function, such as pretreatment with adenosine before transient exposure to caffeine, reduced polyspermic penetration rate and the width of the window for sperm penetration, the incidence was still unacceptable for commercial application. Ultrastructural observations of the zona pellucida of porcine oocytes (Funahashi et al 2000a) have found morphological differences in the zona pellucida of oocytes matured in vitro and in vivo and these authors hypothesized that the differences due to a failure in final maturation may result in incomplete or delayed zona reaction. Polyspermy rate appears to be affected by the donor of oocytes (Marchal et al 2001) and is still higher for in vitro matured oocytes than for ovulated oocytes (Wang et al 1998).…”

Surgical embryo collection but not nonsurgical embryo transfer compromises postintervention prolificacy in sows

“…A volume of 30 mL of protein-free embryo recovery medium, consisting of Tyrode's lactate (TL)-HEPES-polyvinyl alcohol (PVA) (TL-PVA; [11]) with small modifications [4], was introduced into the uterine horn from the tip of the uterine horn using a 60 mL syringe connected to a blunt needle. The flushing medium was forced through the glass cannula into a 50 mL sterile tube by manual massage of the uterus.…”