Stronger pigmentation was observed on the primordia apex exactly at points of densely aggregated hyphae, which leads us to believe that pigmentation is correlated with hyphal aggregation. The term “”hyphal nodules”" has been used to describe the initial phases of basidiomata development [19] as well as for the nodules in the regions of the “”initials”"

and in the morphogenesis-directing primordia [33]. Primordia of M. perniciosa appeared when the dense mycelial mat showed reddish-pink pigmentation. The first signal of primordial development was probably the appearance of primary hyphal nodules as well as internal local aggregations on dark pink-reddish mycelium (Figure 2F). Thereafter, hyphal interaction led to the formation of compact aggregates that can SCH 900776 be considered an undifferentiated stage called initial primordium or secondary hyphal nodule [19] (Figure 3A). Hyphae belonging to such aggregates were short, large and strongly stainable with fuchsin acid, a substance present in Pianeze III solution, used to distinguish fungal from plant tissues (Figure

3A). The primordium emerged from within the surface mycelial layer (Figure 1E) as a well-defined protuberance (Figure 1F) with hyphae similar to those found in the aggregates (Figure 4A). The primordium initial (Figure 1F and Figure 3C) then underwent differentiation to form stipe, pileus Gefitinib in vivo (Figure 4B) and lamellae (Figure 4C). Hyphae of the primordium apex were cylindrical, with round apices and parallel growth, bending at the end distal to the pileus (Figure 4D, detail). Stipe hyphae were more compact,

flat, growing vertically (Figure 4E). Amorphous material and clamped hyphae were also present on the apical primordium surface (Figure 2D and Figure 4F, respectively). Figure 3 Early developmental stages of M. perniciosa basidiomata. A. Globose hyphal aggregate (initial primordium) under a superficial layer of mycelial mat (bar = 0.25 mm). B. SPTLC1 Schematic drawing of the area marked in A showing the grouping of protective hyphae (*) laterally involving another more compact group (#). At the top another group of converging hyphae grows downwards (black squares) (bar = 0.12 mm). C. selleck products Tissue section showing an emerging undifferentiated “”initial”" (bar = 0.25 mm). D. Schematic drawing of C showing the expansion of marked hyphae presented in Figure 2B. The arrows indicate the same previous protective layer but the compact bulb has already overlapped it (bar = 0.25 mm). E. Another “”initial”" in a more advanced developmental state (bar = 0.25 mm). F. Schematic drawing of E showing protective hyphae placed in parallel positions and the laterally expanding bulb hyphae (arrows) (bar = 0.25 mm). Figure 4 Aspect of primordia of M. perniciosa. A. Section of initial primordium stained with Pianeze III. Note the globose form, the distance between the septa and the pigment impregnated within the hyphal cell wall (arrow; bar = 0.1 mm). B.