Fig. 2.

Pollen tube growth, in ‘Nova’ mandarin. (A) Germinating pollen grains in the stigma with pollen tubes oriented toward the stylar canals opening (white line) on the surface of the stigma. (B) Germinated pollen grains (PG) with pollen tubes growing between the stigmatic papillae. (C–E) Pollen tube growth in the style in the upper (C), middle (D) and lower (E) part, showing a reduction in pollen-tube numbers (arrows) along the style, which is accompanied by a reduction in surface area and in the number of cells bordering the stylar canal. (F) Pollen tubes (arrow) reaching the ovary growing on the long papillae, and (G) penetrating the ovule through the micropyle. Paraffin embedded longitudinal (A, B) and transverse (C–G) sections of the pistil stained with aniline blue. Scale bars = 50 µm.