anatomy biology biomaterials biomedical biotechnology collagen crimp fiber fibers fibre fibres material microscope microscopy sveres texture tissue waves abstract Capsella Capsella bursa-pasto embryo enlargment family Brassicaceae magification micro mustard plant seed Shepherd's-purse biological bone cancellous contrast dic differential interference medical spongy sub-chondral trabecular vertebra vertebrae blood capillary cells education haemoglobin human laboratory life oxygen red red blood cells science slide smear tiny autumn barberry Berberis Bér-be-ris colour environment leaf midrib natural nature nerve pepperidge bush set tree