02045naa a2200229 a 450000100080000000500110000800800410001902400350006010000140009524501090010926000090021850000920022752012720031965300110159165300240160265300280162665300190165465300190167370000180169270000190171077300860172910602552019-10-01       2019    bl uuuu     u00u1 u    #d7 a10.1017/S14319276190006922DOI1 aBÁEZ, F.  aUltrastructural imaging analysis of the zona pellucida surface in bovine oocytes.h[electronic resource]  c2019  aArticle history: Received 21 August 2018/ Revised 23 April 2019/Accepted 23 April 2019.  aAbstract: The aims of the present study were to: (i) evaluate the ultrastructural differences in the zona pellucida (ZP) surface between immature and mature bovine oocytes, and (ii) describe a new objective technique to measure the pores in the outer ZP. Intact cumulus oocyte complexes (COCs) obtained from a local abattoir were immediately fixed (immature group) or submitted to in vitro maturation (IVM) at 38.5 °C for 24 h in a humidified atmosphere of 5% CO 2 in air (mature group). Oocytes from both groups were morphologically evaluated via Scanning Electron Microscopy (SEM) and the images were processed in the Fiji/ImageJ software using a new objective methodology through the Trainable Weka Segmentation plugin. The average number of pores in ZP was greater (p < 0.05) in the mature group than the immature group. However, the size and circularity of pores in ZP did not differ (p > 0.05) between groups. In conclusion, it has been shown that the number of pores highlighted the main ultrastructural change in the morphology of the ZP surface of bovine oocytes during the IVM pro-cess. We have described an objective method that can be used to evaluate ultrastructural modifications of the ZP surface during oocyte maturation and early embryo development.  aBOVINE  aIN VITRO MATURATION  aPLATAFORMA SALUD ANIMAL  aULTRASTRUCTURE  aZONA PELLUCIDA1 aCAMARGO, A.A.1 aGASTAL, G.D.A.  tMicroscopy and Microanalysis, 1 August 2019, Volume 25, Issue 4, Pages 1032-1036.