abstract biological biomedical bone cancellous contrast dic differential interference medical microscope microscopy spongy sub-chondral sveres trabecular vertebra vertebrae aubergine berry brinjal cultivars eggplant elongated oval-shaped food fruit glossy guinea squash healthy melongene nightshades nutritional oval-shaped perishable purple shapes smooth Solanaceae Solanum melongena spongy texture taste texture textures variations variety vegetable vegetarian