The nucleolar extrusions containing proteins (-NHa and -SH groups; and tyrosine) and RNA ; mitochondria containing phospholipids, proteins (-NH2 and -SH groups ; and tyrosine); and Golgi bodies having phospholipids arc concentrated in the form of the yolk nucleus in the vicinity of the nucleus in the early stages of oogenesis. The Golgi vesicles appear in the yolk nucleus in developing oocytes. Later on mitochondria, the L, bodies (Golgi vesicles) and nucleolar extrusions get distributed in the whole of ooplasm. RNA helps in protein synthesis and the Golgi vesicles get transformed into lipid yolk globules. Hence the yolk nucleus plays an indirect role in the initiation of vitellogenesis of Panulirus.