*2.9. Histopathology*

Samples of fresh abomasal tissues were washed in a phosphate buffer (0.1 M, pH 7.4), put in plastic containers, and fixed in a 10% buffered FA solution as pieces of tissue spread on a flat piece of polystyrene as previously described [19]. The fixed material was processed using a series of reagents in the following sequence: 75% alcohol for 1 h, 90% alcohol for 1 h, 95% alcohol for 1 h, 100% alcohol 3 times for 1 h. Then, the material was cleared in xylene 3 times for 1 h. The material was infiltrated in paraffin 3 times for 1 h 20 min. The described steps took place in a tissue processor (Excelsior AS Thermo Scientific, Runcorn, UK). Afterward, specimens were embedded in Paraplast PLUS paraffin blocks (Leica, Buffalo Grove, IL, USA), which were then cut with a rotary microtome into sections 2.5 μm thick. Slides with a paraffin section were automatically stained with hematoxylin and eosin (Varistain Gemini Thermo Scientific, Runcorn, UK). An Axio Lab. A1 microscope (Carl Zeiss, Jena, Germany) equipped with a Zeiss Axiocam ERc 5s digital camera was used for histological evaluation. Photographs were analyzed and recorded using ZEN 2.3 (blue edition) software (Carl Zeiss Microscopy GmbH, Oberkochen, Germany, 2011).
