Figure 4

Histological analysis of embryogenic/organogenic callus of V. planifolia on A4 medium and A10 medium 30 days after subculture. Four-micrometer-thick sections of callus were stained with Periodic acid and Schiff' reagent. a. Demarcated and well-differentiated shoot or well-developed PLB in CA10 d30 callus. Vascular tissue (VT) and leaf sheath (LS) can be noticed; bar = 150 μm. b. Strong accumulation of polysaccharides (dashed arrows) in embryogenic callus (EC), particulary in posterior zone of differentiated shoot; bar = 150 μm. c. Higher magnification of the vascular tissue: lengthened vascular cell (VC) connected to well-developed PLB and embryogenic callus (EC) tissue that contains heavy accumulation of polysaccharides (starch); bar = 30 μm. d. Intense mitotic cells zone (MCZ) with vascular cells in CA4 d30; dense meristematic cells or proembryonic cells are also observed and formed PLB. No starch accumulation can be detected in embryogenic callus (EC); bar = 100 μm.