LIFE SCIENCE

Detailed explanation-1: -Vitellogenins (Vtgs) are the predominant egg yolk precursors in oviparous vertebrates. Vtgs are synthesized in the liver under the influence of estrogen, secreted into the bloodstream as  500 kDa homodimers, and bind specific receptors on the surface of growing oocytes during a process termed vitellogenesis.

Detailed explanation-2: -During vitellogenesis, oocytes accumulate two major yolk proteins: vitellin (Vn), which consists of two yolk protein (YP) subunits, YP1 (Mr = 153 000) and YP3 (Mr = 43 000), produced and secreted as vitellogenin (Vg) by the fat body cells (see also Section 1.3.

Detailed explanation-3: -Vitellogenin (Vtg), the major egg yolk precursor protein, is traditionally thought to provide protein-and lipid-rich nutrients for developing embryos and larvae.

Detailed explanation-4: -During vitellogenesis, female-specific proteins, vitellogenins (Vg), are synthesized in the fat body, secreted into the hemolymph and taken up by the developing oocyte.