Fig. 3

Early stage of development of O. robiniae gall on the R. pseudoacacia leaves. a, Bar = 50 μM) Transverse section through a bent edge of fresh leaf; the thickness of the leaf blade in the curved part is the same as in the rest one; some cells in adaxial epidermis are enlarged (arrows); free hand section, no stained. b, c, d; Bar = 20 μM) (b) Transverse section through a initiating gall; inside of some leaf cells any pigmented (orange-brown) material is visible (arrows); fresh section, no stained. c Hydrophobic, heterogeneous material in form of balls (arrows) in leaf cells, mainly in mesophyll; cryostate section from fresh leaf, no stained. d Part of the wall of a initiating gall; fibrous material similar to fungi in epidermis and parenchyma of leaf cells (arrows). The cells of parenchyma in the bundle sheath extension (star) are divided longwise and transversely (bold arrow); free-hand section, no stained. Abbreviations: eb - abaxial epidermis, ed. - adaxial epidermis, m -mesophyll, vb - vascular bundle, * bundle sheath