opening 5 thereof this arrangement protects the wound in the skull from infection other devices can be fixed in a corresponding manner to evaluate the effect of gelatin surrounding implanted electrodes in the tissue we compared the histological reactions 6 weeks in rat brains after implantation to an implanted flat approximately 7 um thick 140 um wide and 2 5 mm long testing device made of su 8 which was either embedded with a thin 5 10 u03bcm layer of gelatin or not all animal related procedures were conducted in accordance with local and international ethical guidelines with the permission of the lund and malm u00f6 ethical board diary numbers m258 11 all implantations n implantations 16 were made in female sprague dawley rats no of rats 8 taconic denmark weighing 200 250 g the animals were anaesthetized using intra peritoneal injections of fentanyl 0 3 mg kg body weight and domitor vet medetomidin hydrochloride 0 3 mg kg and placed in a stereotactic frame for surgery a rostrocaudal incision in the skin was placed along the central suture of the skull to expose bregma an opening of about 2 mm diameter was made 1 0 mm caudally of bregma and 2 3 mm laterally if the midline the dura mater was cut open using a forceps and a.