pinocytic vesicles...is derived form the term , pinocytosis , which itself is a type of endocytosis. the other type is phagocytosis.
pinocytosis invovles the bulk uptake of liquids form the surrounding enviroment of a cell, hence this might include dissolved ions or nutreints....the process starts like this.. nutreints approach the plasma membrane , penetrate through it, a vesicle forms around it and pinches off the memrane.. this action requires energy. This vesicel is known as the pinocytic vesicle....it moves on to internal regions of the cell, where the nutreints diffuse out of the vesicel and get utilized by the it... pinocytosis is also known as cell drinking
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2. i guess the membrane keeps on reforming as vesicles pinches off....
hope i helped