Developmental fate of ovoid oocytes.
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.
Ebner
T
T
Landes- Frauen- und Kinderklinik, IVF-Unit, Krankenhausstr. 26-30, A-4020 Linz, Austria. thomas.ebner@gespag.at
Shebl
O
O
Moser
M
M
Sommergruber
M
M
Tews
G
G
D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D048430:Cell Shape; D002970:Cleavage Stage, Ovum; D047108:Embryonic Development; D005260:Female; D005306:Fertilization; D006801:Humans; D008297:Male; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D020554:Sperm Injections, Intracytoplasmic; D013997:Time Factors; D015053:Zygote / Q000502:physiology