VITELLOGENESIS is the process through which food is
progressively stored in the growing oocytes of oviparous animals, making
up the yolk of the mature egg. The process is remarkably similar in all
animals analyzed so far. There are many common points during the
vitellogenesis of worms, insects and vertebrates (amphibians, reptiles
- Most of the food reserves are producced outside the oocytes and
transported through the body fluids (pseudocoelomic fluid in nematodes,
hemolymph in insects or blood in vertebrates) by soluble proteins.
- The uptake of these proteins by the oocytes is mediated by specific
- The synthesis of these proteins is controled by hormones
(except in nematodes).
- The main proteins involved in the process are called VITELLOGENINS.
They are large proteins (greater than 500 kDa or 500,000 times the mass
of a Hydrogen atom!) and have lipids, carbohydrates and phosphate
associated to them.