Keratinization of the esophageal epithelium of domesticated mammals.

The research article presents a study about keratin characteristics in the esophagus, which is the muscular tube that passes food from the mouth to the stomach, on domesticated animals. The animals belong to three different nutritional groups: herbivores, omnivores, and carnivores. The study used various methods such as histochemistry, sulfur measurements, and cryo-scanning electron microscopy to examine the keratinization.

Methodology

• The research team carried out a histochemical analysis of the esophagus samples taken from a variety of domesticated mammals that are classified into three nutrition groups, namely herbivores (horses, cattle, sheep), omnivores (pigs, dogs, rats), and carnivores (cats).
• They also measured the sulfur content and used cryo-scanning electron microscopy (cryo-SEM) for their examination.
• They analyze the levels of four kinds of keratins: CK6, CK13, CK14, and CK17, which all serve different functions. They also studied the reactions of disulfides, which are important in the formation of keratins.

Key Findings

• The presence of keratins was found in all esophageal layers of all the species they studied, except for the Stratum corneum layer of horses.
• The intensity of the Pan-keratin staining, which is a marker for all keratins, decreased towards the outer layers in all species. The only exceptions were pigs and cats where staining was found only in the corneal layer.
• The herbivores showed positive staining reactions particularly in the upper Stratum spinosum layer, especially in sheep.
• Regarding single keratins, CK6 was found in most of the esophageal layers, and only weakly or negatively in the Stratum corneum of pigs and horses. CK13 was only found in sheep in all layers. CK14 was detected in the basal layer of cats and horses and upper vital layers of dogs and rats. CK17 appeared only in specific layers of certain animals and all layers in dogs and cats.
• Disulfides, which are a significant part in the formation of keratins, reacted strongly in the surface layer (Stratum corneum) of the herbivores, and this was collaboratively evidenced by the sulfur concentrations in the esophagus.

Conclusions

• The researchers concluded that keratins are significant for the mechanical stability of epithelial cells and cell layers in the mammalian esophagus.
• Furthermore, it was highlighted that the role of keratins in the esophageal epithelia of different animals could vary due to specific features like different feed types and mechanical loads that the esophagus of these animals has to handle.