| Since there is no lymph notes in chicken,,mucosa-associated lymphoid tissue(MALT), major peripheral immune organ, plays a significant role in chicken’s immune system. Among the rest of components of MALT,urogenital tract-associated lymphoid tissue is an indispensable component of MALT.It also includs gastrointestinal-associated lymphoid tissue and respiratory-associated lymphoid tissue. For laying hens, establishment of immune function of the genitourinary tract-associated lymphoid tissue directly affects the physiological function, reproductive function and physical health. Ovary is the place where follicles grow up and become mature, and the growth and maturation of ovarian follicles are closely related to the laying performance and the quality of egg. However, as the chicken reproductive tract opens to the outside, the ovary is susceptible to be attacked by external virus, and followed by the direct transmission to the eggs.In order to detect the mRNA expression of Th1 cytokines IFN-γ,IL-2 and Th2 cytokines IL-4,IL-10 in ovary of 7, 14, 21, 35, 56, 90, 140, 210, 280 and 350-day-old hens and explore the growth and regulation of ovary immune function, SYBR Green I real-time PCR was employed in this study. The results showed that :1. The expression level of each gene in 7 to 90 days showed a trend of continuous increase, with a relatively low level from 140 d to 350 d. Except IL-4,the expression of other three cytokines peaked at 90 d. Compared to the beginning of laying, the expression of each gene rebound in the 280 d and 350 d of age. IL-10 peaked at 90 d, while dropped during the 140 d and 210 d, then dropped between the 140 d and 210 d. Different from other cytokines, IL-10 has higher expression level in 140 d to 350 d than that in 7d to 56 d.2.The expression level of IFN-γ were several times higher than the expression level of IL-2, but both of them changed almost at the same trend.3.The expression of IL-4 and IL-10 was different from IFN-γ and IL-2 which was significantly decreased in 140 d. And in 140 d to 350 d, the expression levels of IL-4 and IL-10 exceeded it of IFN-γ and IL-2.4. In addition, when the chicken reach to the pre-laying stage between the growth and development stage until 90 d, the expression levels of IL-4 and IFN-γ were significantly higher than the other two cytokines, with changes maintaining at a fix ratio.5.Expression of IL-2 and IL-10 is always at a relatively low level, 7 to 56 days, the expression level of them is almost the same in the ovary, while at 90 d, the mRNA expression of IL-10 in significantly higher than IL-2, thereafter, in the laying period of hens, the expression of IL-10 also maintained at a higher level compared to IL-2.The results showed that the development of immune system in chicken ovary is closely dependent on the age of chicken.Cytokines expression levels increased with the aging,reached a quite high level at 56 days,then reached its maximum at pre-laying stage. While as the hens become into sexual maturity, they start laying when there was a sharp decline in immune function, and then have rebounded in laying period. The relationship between IL-4 and IFN-γ was balanced, the expression of IL-2 and IL-10 also showed an suppression to each other. In addition, after sexual maturity, although the expression level of the cytokines in ovary lower than before, the expression level of Th2 cytokines has exceeded Th1 cytokines at this period, it suggests that after sexual maturity, the type of immune response in ovarian tends to be dominated by Th2-type humoral immune response.The aim of this study was to provide theoretical basis for the disease prevention in the reproductive system of laying hens, the choice of the optimized time of immunization, and eventually achieving the goal of producing healthy and clean eggs for consumption. |
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