Oogenesis in Xenopus laevis (Daudin). III. Localization of negative charges on the surface of developing oocytes

Journal Article · Thu Jan 01 04:00:00 EST 1976 · J. Ultrastruct. Res.; (United States)

DOI:https://doi.org/10.1016/S0022-5320(76)80077-9· OSTI ID:7319195

Brummett, A R; Dumont, J N

Developing oocytes and coelomic eggs of mature HCG-stimulated Xenopus females were dissected from the ovary, fixed in glutaraldehyde, and treated with a positively charged solution of colloidal iron. Electron micrographs reveal anionic sites preferentially localized in or on the plasmalemma covering the distal portions of the numerous microvilli of Stage IV oocytes. Both prior to and subsequent to Stage IV (the peak of vitellogenic activity), the anionic sites on the oolemma are more randomly distributed. No iron particles appear in endocytotic pits of the oolemma at any stage of development, but endocytotic pits of follicle cells are labeled. There are few if any anionic sites in the vitelline envelope. The assumption that the negative charges are due to sialic acid moieties of surface mucopolysaccharides was borne out by treatment with neuraminidase. Oocytes subjected to the enzyme and subsequently fixed and treated with colloidal iron show a marked reduction in the amount of labeling. These results are discussed in the light of earlier evidence regarding the endocytosis of vitellogenin, a negatively charged molecule.

• Research Organization: Oak Ridge National Lab., TN
• OSTI ID: 7319195
• Journal Information: J. Ultrastruct. Res.; (United States), Journal Name: J. Ultrastruct. Res.; (United States) Vol. 55; ISSN JULRA
• Country of Publication: United States
• Language: English

Related Subjects

551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BIOLOGICAL LOCALIZATION
CARBOHYDRATES
ELEMENTS
FROGS
GAMETOGENESIS
GERM CELLS
IRON
METALS
MUCOPOLYSACCHARIDES
OOCYTES
OOGENESIS
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
TRANSITION ELEMENTS
VERTEBRATES