Insect oogenesis Flashcards
What is oogenesis?
The creation of an egg
What are the main features of a mature ovum?
Contains nutrient storage molecules (yolk) containing a lipoprotein called vitellin
Membranes and associated structures are involved in the fertilisation reaction
Mitochondria
Stored mRNA
Ribosomes
What does yolk do?
Provides energy and nutrients for the developing embryo and is gradually used up during embryonic growth
What are the 5 types of oogenesis?
Solitary Follicular Nutrimentary Autosynthetic Heterosynthetic
Describe autosynthetic oogenesis
The synthesis of the yolk and other stored materials is done by the oocyte itself
There is uptake of low MW precursors of yolk (lipids, aa, carbs) which can be demonstrated by labelling the precursors with radioactive tritium
Observed in polychaetes (annelid worms)
Describe heterosynthetic oogenesis
The synthesis of yolk proteins is by other, non-germ cells (somatic cells)
Characterised by the uptake of the yolk precursor vitellogenin which is later stored as vitellin
Where is vitellogenin produced in insects?
The fat body
What is solitary oogenesis?
No follicle cells or nurse cells
Observed in many Polychaeta
What is follicular oogenesis?
Oocytes are associated with a covering of somatic cells
What is nutrimentrary oogenesis?
Oocytes are associated with sister cells (nurse cells)
