Embedding Sheep Ear Tissue in MMA

An unscathed, untreated right ET of a fresh carcass of a blackface sheep (no. 211) from the above-mentioned study 13/1283 was dissected. Preparation of the tissue followed the protocol provided by Pohl et al. [36 (link)]. Briefly, after dissection, the specimen was fixed in formalin (3.5%, pH 7.4; C. Roth, Karlsruhe, Germany) for two weeks. In contrast to the earlier published protocol [41 (link)], before embedding, three Sterican^® standard needles (0.9 mm x 70 mm; B. Braun Melsungen AG, Melsungen, Germany) were placed by hand in the soft tissue as parallel as possible to the course of the tube as landmarks for the later reconstruction of the sample. Care was taken to remain with the needles outside the cartilaginous ET. The tissue block was dehydrated by using an increasing ethanol series (70%, 80%, 90%, 100%; Merck KGaA, Darmstadt, Germany) and embedded in methyl methacrylate (MMA; Merck). The received block was additionally referenced for further control with the milling of three opposing grooves.