ISSN:
1432-0878
Keywords:
Amphibian oocytes
;
Meiotic maturation
;
Annulate lamellae
;
Cortical endoplasmic reticulum
;
Freeze fracture
;
Xenopus laevis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary During meiotic maturation, the cortex of oocytes of Xenopus laevis undergoes structural reorganization, visualized in this study by freeze-fracture electron microscopy. In the full-grown but immature oocyte, annulate lamellae are dispersed throughout the subcortex of the egg, 5 to 20 μm from the plasma membrane. The annulate lamellae consist of well-organized stacks of membrane with visible pores. Stimulation of meiotic maturation by progesterone leads to disruption of the annulate lamellae and formation of an elaborate cortical endoplasmic reticulum which surrounds the cortical granules and intertwines throughout the cortex of the mature egg. Pore-like structures similar to those previously observed in the subcortical annulate lamellae are observed in the mature cortical endoplasmic reticulum. The cortical endoplasmic reticulum is often in close apposition with the plasma membrane and with membranes of cortical granules, but no junctions are visualized. This study provides further evidence that the cortical endoplasmic reticulum develops during progesterone-stimulated meiotic maturation in vitro, and that the annulate lamellae are precursors to the cortical endoplasmic reticulum.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00215457
Permalink
