Establishment of pollen cohesion in Annona cherimola. (A) Microspore walls show methyl-esterified pectins, and also (B) unesterified pectins. (C) As callose is digested, remnants of callose (white arrow) are observed layering the pollen aperture sites. (D-F) Microspores show crosswall cohesion bridges showing the presence of unesterified pectins. (G-H) Details of crosswall cohesion bridges, showing the presence of methyl-esterified pectins. (I) Phase contrast of a mature pollen grain showing internal cohesion and a joint sporopollenin layering. Specific cell components were localized using antibodies against: methyl-esterified pectin (JIM7) (A, G-H), unesterified pectin (JIM5) (B, D, E, F) Callose (C). A-E, I: Bar = 10 μm. F-H: Bar = 3 μm.