Confocal microscopy of F-actin distribution in Xenopus oocytes.
We have used rhodamine-conjugated phalloidin and confocal microscopy to examine the organisation of filamentous actin (F-actin) during oogenesis in Xenopus laevis. F-actin was restricted to a thin shell in the cortex of oogonia and post-mitotic oocytes less than 35 microns in diameter. In oocytes with diameters of 35-50 microns, F-actin was observed in three cellular domains: in the cortex, in the germinal vesicle (GV) and in a network of cytoplasmic cables. Initially, actin cables were sparsely distributed in the cytoplasm, with no evidence of discrete organising centres. In larger stage I oocytes, a dense network of actin cables extended throughout the cytoplasm, linking the GV and mitochondrial mass to the cortical actin shell. Apart from the F-actin associated with the mitochondrial mass, no evidence of a polarised distribution of F-actin was apparent in stage I oocytes. F-actin was observed also in the cortex and the GV of stage VI oocytes, and a network of cytoplasmic cables surrounded the GV. Cytoplasmic actin cables extended from the GV to the animal cortex, and formed a three-dimensional network surrounding clusters of yolk platelets in the vegetal cytoplasm. Finally, disruption of F-actin in stage VI oocytes with cytochalasin resulted in distortion and apparent rotation of the GV in the animal hemisphere, suggesting that actin plays a role in maintaining the polarised organisation of amphibian oocytes.
Roeder
A D
AD
Department of Biology, University of Utah, Salt Lake City 84112.
Gard
D L
DL
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D018613:Microscopy, Confocal; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D009866:Oogenesis / Q000502:physiology; D009867:Oogonia / Q000378:metabolism / Q000648:ultrastructure; D010590:Phalloidine; D012235:Rhodamines; D014982:Xenopus laevis / Q000033:anatomy & histology / Q000378:metabolism*
D000199:Actins; D012235:Rhodamines; D010590:Phalloidine