Fig. 1.

Representative diagram describing the regulatory mechanism of the recruitment of cytotoxic cells in hen oviduct, and eggshell malformation caused by infection. Cytokines are released and cytotoxic cells are recruited through the interaction between Tool-like receptors and its ligands by pathogenic bacteria and virus infection in hen oviductal mucosa. These immunoresponse is weakened during molting phase, but estrogen is likely to enhance this response. IL-1β and IL-6 produced by pathological microbe infection lead eggshell malformation through the degradation of calbindin protein. It is likely the cytotoxic cells and cytotoxic factors led by infection also affects eggshell malformation.