All the vaccines mentioned below are attenuated or inactivated whole pathogen except
All the vaccines mentioned below are attenuated or inactivated whole pathogen except
Select an option to attempt
Correct Answer: Option B
Explanation
The endothecium is the second layer of the anther wall (beneath the epidermis). It develops fibrous thickenings of cellulose and lignin bands on radial and inner tangential walls during pollen maturation — these are the 'fibrous bands' (NOT callose — callose is a transient wall material in young microspores). At pollen maturity, the endothecium cells desiccate and the hygroscopic fibrous thickenings shrink differentially, generating mechanical stress that causes the anther wall to rupture along the stomium — this is DEHISCENCE, allowing pollen release. The endothecium thus functions primarily as a mechanical actuator for pollen dispersal, not for nutrition or protection.