Mitochondrial distribution patterns in canine oocytes as related to the reproductive cycle stage.
This study investigates the mitochondrial (mt) distribution in canine ovarian oocytes examined at recovery time, as related to the reproductive cycle stage, and in oviductal oocytes. Ovarian Germinal Vesicle (GV) stage oocytes were recovered from bitches in anestrous (A, n=2), follicular phase (F, n=4), ovulation (O, n=2), early luteal (EL, n=7) and mid/late luteal phase (MLL, n=2). Oviductal GV, metaphase I (MI) or MII stage oocytes were recovered from six bitches between 56 and 110 h after ovulation. Mitochondria were revealed by using MitoTracker Orange CMTM Ros and confocal microscopy. In ovarian oocytes, three mt distribution patterns were found: (I) small aggregates diffused throughout the cytoplasm; (II) diffused tubular networks; (III) pericortical tubular networks. Significantly higher rates of oocytes showing heterogeneous mt patterns (II+III) were obtained from bitches in F (75%) and in O (96%) compared with bitches in A (31%; F vs. A: P<0.05; O vs. A: P<0.001), in EL (61%; O vs. EL: P<0.01), or in MLL (0%; F vs. MLL: P<0.05; O vs. MLL: P<0.001). Fluorescence intensity did not vary according to mt distribution pattern except that it was lower in oocytes recovered in EL phase and showing small mt aggregations (P<0.001). The majority of ovulated MII stage oocytes (79%) showed diffused tubular mt network. We conclude that mt distribution pattern of canine ovarian immature oocytes changes in relation to reproductive cycle stage and that patterns observed in oocytes recovered from bitches in periovulatory phases are heterogeneous and similar to those of in vivo matured oocytes.
Department of Animal Production, University of Bari, Strada Provinciale per Casamassima km 3, 70010 Valenzano, Bari, Italy.
Luisa
L
Valentini
Alina Iulia
AI
Iorga
Teresa
T
De Santis
Barbara
B
Ambruosi
Karine
K
Reynaud
Sylvie
S
Chastant-Maillard
Antonio Ciro
AC
Guaricci
Michele
M
Caira
Maria Elena
ME
Dell'Aquila
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D002843:Chromatin / Q000648:ultrastructure; D004285:Dogs / Q000033:anatomy & histology* / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D005456:Fluorescent Dyes; D008540:Meiosis; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000648:ultrastructure*; D009865:Oocytes / Q000254:growth & development / Q000648:ultrastructure*; D010060:Ovulation / Q000502:physiology
D002843:Chromatin; D005456:Fluorescent Dyes