Chromatin, microtubule and microfilament configurations in the canine oocyte.
In the present study, we observed chromatin, microtubule and microfilament distribution in canine oocytes. The germinal vesicle (GV) chromatin of canine oocytes was classified into four configurations (GV-I, -II, -III and -IV) based on the degree of chromatin separation and condensation. Oocytes recovered from follicular phase ovaries had a greater amount (68%, P < 0.05) of GV-III or GV-IV chromatin than did those from non-follicular phase ovaries (35%). The majority (86.7%) of in vivo ovulated oocytes were at GV-IV. The rates of development to GV breakdown/metaphase I/metaphase II were higher in oocytes recovered from follicular ovaries than from non-follicular ovaries. Immunostaining results revealed cytoplasmic microtubules present in all GV-stage oocytes. Following GV breakdown, microtubular asters were produced from condensed chromatin. The asters appeared to be elongated, and encompassed condensed chromatin particles to form meiotic metaphase chromatin. Microfilaments were located in the cortex and around the GV. During meiotic maturation, a microfilament-rich area, in which the chromatin is allocated, was observed in the oocyte. Our results indicate that oocytes recovered from follicular ovaries were in an advanced stage of GV, and were more competent to complete maturation compared to those from non-follicular phase ovaries. Both microtubules and microfilaments are closely associated with reconstruction of chromatin during meiotic maturation in canine oocytes.
Jin
Yong-Xun
YX
Department of Animal Sciences, Chungbuk National University, Cheongju, Chungbuk 361-763, South Korea.
Lee
Hyo-Sang
HS
Yin
Xi-Jun
XJ
Cui
Xiang-Shun
XS
Kong
Il-Keun
IK
Kim
Nam-Hyung
NH
D008841:Actin Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D002843:Chromatin / Q000502:physiology* / Q000648:ultrastructure; D004285:Dogs; D005260:Female; D008540:Meiosis / Q000502:physiology; D008856:Microscopy, Fluorescence / Q000662:veterinary; D008870:Microtubules / Q000502:physiology* / Q000648:ultrastructure; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure; D006080:Ovarian Follicle / Q000502:physiology*
D002843:Chromatin