Oogenesis in Xenopus laevis (Daudin)
In Xenopus laevis, vitellogenin (the yolk precursor) is synthesized in the liver and transported via the circulatory system to the ovary. In order to reach developing oocytes where it is sequestered, it must exit the circulatory system and traverse several follicular tissue layers including the theca, the follicle cell layer, and the vitelline envelope. This study demonstrates this pathway by means of electron-opaque tracers, and follows the fate of heterologous macromolecules after their incorporation into the ooplasm. The tracers used were horseradish peroxidase, iron dextran, ferritin, and thorotrast. The bulk of the tracers exit the circulatory system through gaps between adjacent capillary endothelial cells and migrate into the connective tissue theca, where they appear randomly dispersed. All tracers, except thorotrast, penetrate the basement membrane on the distal surface of the follicle cells and pass through channels between adjacent follicle cells into the vitelline envelope and to the surface of developing oocytes, where they are incorporated by endocytosis.Endosomes which contain tracer, and also presumably vitellogenin, fuse to form primordial yolk platelets. During this fusion process an extensive network of smooth-surfaced tubules arises in the peripheral ooplasm. Endosomes and/or primordial yolk platelets continue to fuse with each other, resulting in the growth of primordial platelets which move deeper into the ooplasm, where they are transformed into yolk platelets with crystalline main bodies. Peroxidase and iron dextran remain in the superficial layer of the platelet, while ferritin is present in both the superficial layer and the crystalline main body.
- Research Organization:
- Oak Ridge National Lab., TN
- OSTI ID:
- 5827768
- Journal Information:
- J. Exp. Zool.; (United States), Journal Name: J. Exp. Zool.; (United States) Vol. 204:2; ISSN JEZOA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Oogenesis in Xenopus laevis (Daudin). III. Localization of negative charges on the surface of developing oocytes
Intracellular transport of vitellogenin in Xenopus oocytes: an autoradiographic study
Related Subjects
550301 -- Cytology-- Tracer Techniques
551000 -- Physiological Systems
551001 -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACTINIDE COMPOUNDS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BIOLOGICAL PATHWAYS
BLOOD SUBSTITUTES
BODY
CARBOHYDRATES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CHALCOGENIDES
COLLOIDS
COMPLEXES
CONTRAST MEDIA
DEXTRAN
DIGESTIVE SYSTEM
DISPERSIONS
ENDOTHELIUM
ENZYMES
FEMALE GENITALS
FERRITIN
GAMETOGENESIS
GERM CELLS
GLANDS
GONADS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IRON COMPLEXES
IRON COMPOUNDS
KIDNEYS
LIVER
MEMBRANE TRANSPORT
OOCYTES
OOGENESIS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OVARIES
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
POLYSACCHARIDES
PORPHYRINS
PROTEINS
RADIOCOLLOIDS
RADIONUCLIDE KINETICS
SACCHARIDES
THORIUM COMPOUNDS
THORIUM OXIDES
THOROTRAST
TISSUES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
TUBULES
VERTEBRATES