We have visualized macroscopic transient pores in mechanically stretched gi
ant vesicles. They can be observed only if the vesicles are prepared in a v
iscous solution to slow down the leak-out of the internal liquid. We study
here theoretically the full dynamics of growth (driven by surface tension)
and closure (driven by line tension) of these large pores. We write two cou
pled equations of the time evolution of the radii r(t) of the hole and R(t)
of the vesicle, which both act on the release of the membrane tension. We
find four periods in the life of a transient pore: (I) exponential growth o
f the young pore; (II) stop of the growth at a maximum radius ih,; (III) sl
ow closure limited by the leak-out; (IV) fast closure below a critical radi
us, when leak-out becomes negligible. Ultimately the membrane is completely
resealed. (C) 2000 Elsevier Science B.V. All rights reserved.