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    The histochemistry and endocrine control of vitellogenesis in goldfish ovaries
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    Abstract:
    Histological and histochemical examinations of goldfish ovaries indicate that two types of yolk inclusions are formed during vitellogenesis: first, yolk vesicles, comprised of mucopolysaccharides, followed by yolk granules composed of protein, phospholipid, and neutral lipids. Neither type of yolk develops in the absence of the pituitary. Estrogens regulate the formation of yolk vesicles, while pregnenolone was found to control the deposition of yolk granules. The significance of these two kinds of yolk is discussed. This is the first demonstration of a separate endocrine control for the formation of each of the two yolk types in goldfish ovaries.
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    Yolk
    The distinctive characteristics found in each of the development stages of the oocyte in the ovary of Lutjanus peru (Pacific red snapper) are described. The histological technique was used to identify the development stages of the oocytes and the averages of the diameters of the oocytes were obtained for these stages. Stage I, chromatin nucleolus oocyte: average diameter of 52.89 µm. Stage II, perinucleolus oocyte: average diameter of 117.78 µm. Stage III, yolk vesicle oocyte: average diameter of 166.18 µm. Stage IV, primary vitellogenesis oocyte: average diameter of 221.73 µm. Stage V, secondary vitellogenesis oocyte: average diameter of 333.7 µm. Stage VI, tertiary vitellogenesis oocyte: average diameter of 340.17 µm. Stage VII, mature oocyte: average diameter of 340.17 µm. With the identification of these stages, the observation of the process of the oogenesis in L. peru has been completed.
    Yolk
    Germinal vesicle
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    Histological and histochemical examinations of goldfish ovaries indicate that two types of yolk inclusions are formed during vitellogenesis: first, yolk vesicles, comprised of mucopolysaccharides, followed by yolk granules composed of protein, phospholipid, and neutral lipids. Neither type of yolk develops in the absence of the pituitary. Estrogens regulate the formation of yolk vesicles, while pregnenolone was found to control the deposition of yolk granules. The significance of these two kinds of yolk is discussed. This is the first demonstration of a separate endocrine control for the formation of each of the two yolk types in goldfish ovaries.
    Yolk
    Citations (111)
    Yolk globules in developing oocytes of Tilapia mosambique are formed by two processes: 1) biosynthetical activity of oocyte organoides; 2) vitellogenin migration by micropinocytosis and its further transformation. Undoubtedly, yolk globules of endogenic and exogenic origin are fused. The primary yolk globules are spherical, and the secondary ones are lobular. The latter originate by incorporating the former. The fast growth of the late vitellogenic stage oocytes occurs as a result of active migration of primary yolk globules into the central part of the oocyte and as their association with the secondary yolk globules. In vitellogenic oocytes of T. mosambique no yolk vesicles (cortical granules), were found by any existing methods.
    Yolk
    Vitellogenin
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