Preparation of medicinal plants tissues for scanning electron microscopy (SEM)

Since the glandular trichome in the medicinal plants is the location for storage and synthesis of essential oils, glandular trichomes are widely distributed all of the plant organs of the Lamiaceae, their secretions contribute largely to its great importance. They are the primary secretory organs of these plants, and their structures can vary widely among species. Therefore, their morphology could be, addition of taxonomical importance, to have essential oils which are widely used in pharmaceutical and cosmetic industry. Therefore, identification of a protocol that would preserve tissue size and morphology by usual methods can be useful. In this study compared two of the method by quantifying changes in size and trichome shrinkage percent at two different organs (leaf and calyx) in three Nepeta species studied: Nepeta. fissa, Nepeta. assurgens and Nepeta. eremophilla. Plant materials washed in distillated water, then immersed in FAA fixative (3.7% v/v formaldehyde, 50% ethanol, 5% acetic acid) and was then fixed (approximately 3 h) at 4°C. Tissue was rinsed three times in sodium phosphate buffer before dehydrating in a methanol series (30%, 50%, 70%, 95%, and 100%), 5 min each step. Specimens were mounted onto SEM stubs and coated with paladium. The method used depend on the type of plant species and different organs, in this study shows that generally the fixation and dehydration with methanol is a quick and simple method for preservation the size and shrinking of plant the tissues.