裸圓形卵細胞受孕率與正常卵細胞相似
裸圓形卵細胞之細胞分裂率及懷孕率較正常卵細胞為低
裸圓形卵細胞之胚胎著床率較正常卵細胞為低
http://humrep.oxfordjournals.org/content/23/1/62.full
Developmental fate of ovoid oocytes
+Author Affiliations
- 1Correspondence address. E-mail: thomas.ebner@gespag.at
- Received March 28, 2007.
- Revision received June 14, 2007.
- Accepted August 13, 2007.
Abstract
BACKGROUND Irregularities in composition, thickness and/or color of the zona pellucida may impair optimal function and result in reduced outcome. Anomalies of oocyte shape have not been investigated in detail in this respect.
METHODS Therefore, all patients attending our clinic within a period of 1 year were screened for the presence of ovoid gametes and the corresponding developmental potential was evaluated. For all elongated gametes, a roundness index (RI; length divided by width) was calculated in order to quantify shape.
RESULTS RI did not affect fertilizability (P > 0.05). The degree of dysmorphism was found to be related to cleavage pattern. The more ovoid a gamete was, the higher was the risk of the corresponding zygote not cleaving like a tetrahedron (P < 0.01). Abnormal cleavage (a rather flat array of blastomeres) was associated with delayed compaction (P < 0.01) and blastocyst formation (P < 0.001). The quality of blastocysts was not affected at any stage in ovoid concepti (P > 0.05).
CONCLUSIONS Ovoid oocytes with abnormal cleavage pattern show delayed preimplantation development, probably due to a reduced number of cell-to-cell contacts.
Figure 1:
Shape anomalies of oocytes (a) Ovoid oocyte with RI of 1.50 (oocyte) and 1.82 (ZP). (b) Round oocyte (RI of 1.02) with ovoid ZP (RI of 1.20). Arrow indicates splitting of inner layer of ZP.
Figure 2:
Cleavage patterns of Day 2 embryos (a) Regularly cleaved four-cell embryo with ovoid ZP (RI of 1.40). Asterisks indicate cell–cell contacts between blastomeres (n = 6). (b) Irregular Day 2 embryo with one cleavage plane (RI of 1.44) and only four cell–cell contacts between blastomeres (asterisks)
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