2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/468Molecular gas plays an important role in the structure of planetary nebulae: it is a major component of the equatorial tori of bipolar nebulae, it forms the cores of globules and related mircostructures, and is the likely origin of multiple arcs. It is also a key component during the early stages of formation where interactions with outflows or jets provide an important shaping mechanism.To appear in ``Asymmetrical Planetary Nebulae II: from Origins to Microstructures'', ASP Conference Series, Vol. 199, 2000; J.H. Kastner, N. Soker, and S.A. Rappaport, edsAstrophysicstext