PMC:3248852 / 4512-6820
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/3248852","sourcedb":"PMC","sourceid":"3248852","source_url":"http://www.ncbi.nlm.nih.gov/pmc/3248852","text":"Intracellular environment of the prophase Rana pipiens oocyte\nFigure 1 illustrates a transmission electron micrograph (× 12,500) of the fully grown Rana pipiens oocyte in prophase arrest. The micrograph depicts a cortical region of the animal hemisphere of an unstimulated prophase Rana pipiens oocyte showing the interface between the membrane microvilli and the inert matrix, called the vitelline membrane (VM), on the oocyte surface. Two of the large yolk platelets are indicated (Y) and three large cortical granules (CG) are visible at the microvillar interface. Numerous small round mitochondria can be seen just below the oocyte plasma membrane. The system of stacked membranes below center are the annulate lamellae [7]. In contrast to the animal hemisphere, the vegetal hemisphere is packed with yolk platelets of varying sizes (not shown)\nFigure 1 A transmission electron micrograph (×12,000) of a prophase-arrested, untreated ovarian follicle from hibernating Rana pipiens. An area of the oocyte cortex with vitelline membrane (VM), oocyte surface microvilli, cortical granules (CG) and yolk platelets (Y) was selected. Annulate lamellae (membrane array below center of figure), numerous mitochondria and other vesicles are visible. Follicles were fixed sequentially with OsO4 and glutaraldehyde and post-fixed in 1% buffered OsO4 for 1.5 h as described [18]. Samples were embedded in Epon and 50 to 80 nm sections were stained with uranyl acetate and then counter stained with lead citrate. Micrographs were taken using a Jeol 100 CX electron microscope at 80 KV. The ultrastructure of yolk platelets from Rana oocytes consists of a central main body with a crystalline lattice structure, with an enclosing membrane approximately 70 Å in thickness [8]. Electron micrographs of the main body reveal hexagonal net, square net and parallel band patterns. The lipoprotein complex, vitellogen, contains 12% lipid and smaller amounts of carbohydrates and biliverdin [9]. Fluorescence confocal microscopy, using a pH-sensitive fluorescent dye, indicates that the mature yolk platelets are acidic (pH 5.6) [10]. As shown previously, about 85% of the Rana pipiens oocyte dry weight is recovered with the yolk platelet fraction isolated by differential centrifugation of 0.24 M sucrose homogenates [11].","divisions":[{"label":"Title","span":{"begin":0,"end":61}},{"label":"Figure caption","span":{"begin":849,"end":1578}}],"tracks":[{"project":"2_test","denotations":[{"id":"22054214-22080920-9450411","span":{"begin":1367,"end":1369},"obj":"22080920"},{"id":"22054214-13962448-9450412","span":{"begin":1764,"end":1765},"obj":"13962448"},{"id":"22054214-5131731-9450413","span":{"begin":1976,"end":1977},"obj":"5131731"},{"id":"22054214-7706389-9450414","span":{"begin":2114,"end":2116},"obj":"7706389"}],"attributes":[{"subj":"22054214-22080920-9450411","pred":"source","obj":"2_test"},{"subj":"22054214-13962448-9450412","pred":"source","obj":"2_test"},{"subj":"22054214-5131731-9450413","pred":"source","obj":"2_test"},{"subj":"22054214-7706389-9450414","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"2_test","color":"#d193ec","default":true}]}]}}