 During this process, the pollen grain undergoes a conformational change whereupon a given section begins to protrude outwards to form a tube-like structure, known as the pollen tube.
<clarity>  During this process, the pollen grain undergoes a conformational change whereupon a given section begins to protrude outwards to form a tube-like structure, known as the pollen tube.
 During this process, the pollen grain begins to bulge outwards to form a tube-like structure, known as the pollen tube.