Med. Weter. 72 (1), 68-74, 2016
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| Bukowska D., Kempisty B., Ziółkowska A., Piotrowska H., Woźna M., Ciesiółka S., Chachuła A., Antosik P., Wojtanowicz-Markiewicz K. Jopek K., Maryniak H., Bruska M., Brüssow K.-P., Nowicki M., Zabel M. |
| Expression and distribution of zona pellucida proteins 3 and 4 in morphologically abnormal canine oocytes: a confocal microscopic observation-based study |
| The morphology of mammalian oocytes significantly determines their ability to grow and develop. It has been clearly demonstrated that cumulus-oocyte complexes (COCs) of abnormal quality have low developmental competence, especially in terms of their maturation and fertilization ability. However, few data are available on the expression of proteins responsible for fertilization in morphologically abnormal oocytes as a possible cause of failed fertilization. This study was aimed at analyzing the expression and distribution of ZP3 and ZP4 glycoproteins within canine oocytes. Canine COCs were morphologically evaluated following their recovery from anestrus mongrel bitches after ovariohysterectomy. Only morphologically abnormal, denuded oocytes with a strongly heterogenous and dark cytoplasm were used in further stages of experiments. The authors found a decreased expression of ZP3 glycoprotein within the oocyte’s cytoplasm, whereas the expression of ZP4 was significantly more pronounced. In almost all oocytes, ZP3 glycoprotein was distributed in the oocytes’ cytoplasm. However, a less pronounced expression of ZP4 was detected within the zona, as well. Using the DAPI staining assay, a proper chromatin configuration was found in only approximately 15% of canine oocytes analyzed. All confocal microscopic observations and analyses were performed by the Imaris 7.2 software (BitPlane, Zurich, Switzerland). Our results suggest that a decreased expression of ZP3 glycoprotein as the primary sperm receptor, as well as its pronounced cytoplasmic location, might explain failed fertilization in this group of canine oocytes. Moreover, the specific staining of ZP4, distributed within the zona, might reflect a significant role of this glycoprotein in fertilization in canines, or this partial distribution may represent remnants of the protein’s strong expression during the early stages of oogenesis and zona formation. Several irregularities found in the expression profiles of both ZP3 and ZP4 reflect the differential distribution of these proteins in oocytes during oogenesis. |
| Key words: zona pellucida, protein expression, confocal microscopy |