The dynamics of in vitro maturation of germinal vesicle oocytes.
OBJECTIVE
To evaluate the dynamics of the nuclear maturation (NM) of in vitro-matured (IVM) oocytes and to determine the most favorable duration of meiosis II (MII) arrest in relation to the normal activation response.


METHODS
Experimental.


METHODS
University-affiliated infertility clinic.


METHODS
Donated immature germinal vesicle oocytes (GV).


METHODS
The GV underwent spontaneous IVM and the dynamics of NM studied by real-time monitoring. The IVM oocytes were parthenogenetically activated at different MII arrest points and their response assessed.


METHODS
Moment of GV breakdown; extrusion of the first polar body; duration of MI and MII arrest; activation rate (AR) and type.


RESULTS
Two GV populations-early (E-IVM, 18.4 ± 2.7 hours) and late (L-IVM, 26.3 ± 3.8 hours) maturing-were defined according to the time required for extrusion of the first polar body. Significantly more E-IVM than L-IVM exhibited a normal activation response (61.3% vs. 34.6%), but AR were similar (average, 88.6%) in both groups. Duration of the GV stage differed between the two groups, but MI arrest (14.0 ± 0.3 hours) was constant. The E-IVM arrested at MII for at least 4.3 hours displayed significantly lower AR and similar normal activation rates (61.3%) to E-IVM arrested for a shorter time (83.9% vs. 100%). The L-IVM displayed a similar AR (80.8%), but lower normal activation rates than E-IVM (34.6%), regardless of when activation took place.


CONCLUSIONS
The success of IVM depends on the NM timing rather than on the length of MII arrest.
Instituto Universitario IVI Valencia, Valencia, Spain.
Laura
L
Escrich
Noelia
N
Grau
María José
MJ
de los Santos
Josep-Lluis
JL
Romero
Antonio
A
Pellicer
María-José
MJ
Escribá
D000328:Adult; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques; D008540:Meiosis / Q000187:drug effects; D018587:Oocyte Donation; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010312:Parthenogenesis; D059705:Polar Bodies / Q000502:physiology; D011691:Puromycin / Q000494:pharmacology; D013997:Time Factors; D059008:Time-Lapse Imaging; D055815:Young Adult
D011691:Puromycin