Development of the yolk nucleus of previtellogenic oocytes in rainbow trout, Oncorhynchus mykiss, studied by light microscopy

In this study, the development of the yolk nucleus in cytoplasm of previtellogenic oocytes was examined by light microscopy during oogenesis in trout, Oncorhynchus mykiss. We determined that oocytes 20-30 um in diameter have much basophilic (electron dense) cytoplasm and an area of flocculent appearance begins to emerge around the nucleus. The yolk nucleus was first recognized within this area as a few fragments dense granular thread. These fragments were observed gradually increase in number and length until they assemble into a spherical mass. When oocytes develop to greater than 107 um in diameter, the yolk nucleus was dispersed throughout the cytoplasm and the cytoplasm was observed more homogenous.

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[1]. Droller MJ, Roth TF. 1966. An electron microscope study of yolk formation during oogenesis in Lebistesreticulatus uppyi. Cell Biology. 28: 209-232.
[2]. Azevedo, C. 1984. Development and ultrastructural autoradiographic studies of nucleolus-like bodies (nuages) in oocytes of viviparous teleost (Xiphophorus helleri). Cell & Tissue Research, 238: 121-128.
[3]. Guraya, SS. 1986. The cell and molecular biology offish oogenesis. (Monographs in Developmental Biology, Vol 18) Basel,New York: Karger. 223 p.
[4]. Raven, CP. 1961. Oogenesis: the storage of developmental information. Oxford, Pergamon Press. 274 p.
[5]. Kobayashi H, Iwamatsu T. 2000. Development and fine structure of the yolk nucleus of previtellogenic oocytes in medaka Oryzias latipes. Development Growth Differantiation, 42:623-631.
[6]. Yamamoto, M. 1964. Electron microscopy of fish development. Ill Changes in ultrastructure of nucleus and cytoplasm of oocytes of goldfish during the first growth phase. Memoirs of the Faculty of Fisheries, Hokkaido University, 13:79-106.
[7]. Beams HW, Kessel RG. 1973. Oocytes structures and early vitellogenesis in the trout, Salmo gairdneri. American Journal of Anatomy, 136:105_____-122.
[8]. Kjesbu OS, Kryvi H. 1998. Oogenesis in cod, Gadus morhua L., studied by ligth and electron microscopy. Journal of Fish Biology, 34:735-746.
[9]. Mufioz M, Sâbat M, Mallol S, CasadeVall M. 2002. Gonadal structure and gametogenesis of Trigla lyra (Pisces: Triglidae). Zoological Studies, 41:412-420.
[10]. Iwamatsu T, Nakashima S. 1996. Dynamic growth of oocytes of medaka, Oryzias latipes- Stages of oocytes development. Zoological Science, 5: 353-373.
[11]. Tyler CA, Sumpter JP. 1996. Oocyte growth and development in teleost, Reviews in Fish Biology and Fisheries. 6: 287-318. .
[12]. Wallace RA, Selman K. 1981. Cellular and dynamic aspects of oocyte growth in teleosts. American Zoology, 21:325-343.
[13]. Bielanska-Osuchowska, Z. 2006. Oogenesis in pig ovaries during the prenatal period: ultrastructure and morphometry. Reproductive Biology, 6 (2): 161-193