Follicular size affects the meiotic competence of in vitro matured prepubertal and adult oocytes in sheep.
Non-atretic follicles dissected from prepubertal and adult ovaries were allocated in three groups: a) < 1 mm; b) 1-2 mm; c) > 2 mm. After 24 h of maturation, a lower percentage of adult oocytes from group a (P < 0.01) reached metaphase II than those from groups b and c (70.4 versus 89.5 and 95.5). Prepubertal oocytes showed similar results (P < 0.01; 27.2 versus 79.8 and 81.8). There was a significant difference (P < 0.01) in meiotic progression between prepubertal and adult oocytes of < 1 mm follicles. The diameter of prepubertal oocytes derived from group a was significantly lower (P < 0.01) compared to groups b and c (138.1 versus 142.1 and 145.6); adult oocytes showed similar results (P < 0.01; 142.2 versus 157.2 and 158.1). Oocytes with the same diameter derived from different follicles of prepubertal and adult ovaries showed similar meiotic progression rates.
Ledda
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S
Department of Animal Biology, Veterinary Faculty, Sassari, Italy. vetfis@ssmain.uniss.it
Bogliolo
L
L
Leoni
G
G
Naitana
S
S
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D008540:Meiosis; D009865:Oocytes / Q000166:cytology* / Q000502:physiology; D006080:Ovarian Follicle / Q000033:anatomy & histology*; D012741:Sexual Maturation; D012756:Sheep