Histology of the abomasum. Histological section of the abomasum of a Swiss Braunvieh cow with lymphosarcoma. There is infiltration of large round lymphoblasts measuring 10 to 15 μm with sparse cytoplasm and round to oval nuclei in the tunica submucosa and tunica muscularis. The chromatin appears vesicular and there are sporadic nucleoli. Haematoxylin and eosin stain.