Prematuration of bovine oocytes with butyrolactone I reversibly arrests meiosis without increasing meiotic abnormalities after in vitro maturation.
OBJECTIVE
Asynchrony between nuclear and cytoplasmic maturation, and possibly damage to the oocyte meiotic spindle, limits the application of in vitro maturation (IVM) in assisted reproduction. Several studies have suggested that Prematuration with meiosis blockers may improve oocyte quality after IVM, favoring early embryogenesis. Thus, we investigated the effect of Prematuration with the nuclear maturation inhibitor butyrolactone I (BLI) on the meiotic spindle and chromosomal configuration of bovine oocytes.


METHODS
Immature oocytes obtained from cows slaughtered in a slaughterhouse (n=840) were divided into the following groups: (1) control (n=325), submitted only to IVM in TCM199 for 24h; (2) BLI 18h (n=208) submitted to meiotic blockage with 100 microM BLI for 24h (Prematuration) and then induction of IVM in TCM199 for 18h; and (3) BLI 24h (n=307), pre-matured with 100 microM BLI for 24h followed by 24h of IVM in TCM199. The oocytes were then fixed, stained by immunofluorescence for morphological visualization of both microtubules and chromatin, and evaluated.


RESULTS
Meiotic arrest occurred in 90.2% of the oocytes cultured with BLI. Maturation rates were similar for all groups (80.3%, 73.6% and 82.7% for the control, BLI 18h and BLI 24h groups, respectively). We observed 81.3% normal oocytes in metaphase II in the control group, and 80.0% and 81.2% in the BLI 18h and BLI 24h groups, respectively. The incidence of meiotic anomalies did not differ between groups (18.7%, 20.0% and 18.8% for the control, BLI 18h and BLI 24h, respectively).


CONCLUSIONS
Prematuration with butyrolactone I reversibly arrests meiosis without damaging the meiotic spindle or the chromosome distribution of bovine oocytes after in vitro maturation.
Ferreira
Elisa Melo
EM
Departamento de Ginecologia e Obstetrícia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil.
Vireque
Alessandra Aparecida
AA
Adona
Paulo Roberto
PR
Ferriani
Rui Alberto
RA
Navarro
Paula Andrea
PA
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D002875:Chromosomes / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D008540:Meiosis / Q000187:drug effects*; D008870:Microtubules / Q000187:drug effects; D023421:Models, Animal; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D027724:Reproductive Techniques, Assisted; D008941:Spindle Apparatus / Q000187:drug effects
D047428:Protein Kinase Inhibitors; C082868:butyrolactone I; D015107:4-Butyrolactone