This repetitive phenotypic change is also accompanied by dramatic changes in gene expression profiles. The aims of this study were to: 1) investigate the physiological changes and gene expression profiles in reproductive organs of laying hens during molting; 2) identify novel genes and their interactions related to reproductive tissue remodeling; and 3) determine epigenetic mechanisms affecting the reproductive tract of laying hens during regression, remodeling and recrudescence associated with the period of molting. Along with completion of sequencing of the chicken genome, many applications of chicken DNA microarrays have led to massive increase in the discovery of genes whose expression is stimulated by estrogen, differential genes expression in the oviduct between immature versus mature hens, and between 3 h versus 20 h post-ovulation. In the present study, we induced molting and changes in oviductal status by feeding high levels of zinc in the diet and assessed its suitability for investigations of molecular mechanisms controlling premolting and post-molting processes. Using cDNA microarray analysis, we now report large-scale gene expression profiles for the oviducts of laying hens during the molting and recrudescence periods. We also determined spatio-temporal specific mRNA expression patterns and validated chicken microRNAs regulating these genes post-transcriptionally. Our approach contributes to the development of novel insights into degeneration and regeneration mechanisms of female reproductive organ at the molecular level. The molting process leads to dynamic changes in morphology, physiology and function of the reproductive tract of laying hens. In the present study, results from differential gene profiling identified global genes that potentially regulate oviductal regression and recrudescence during and following molting. Our results also revealed spatial and temporal expression of selected candidate genes in the magnum during tissue remodeling and posttranscriptional regulation of these genes by specific chicken miRNAs. These results support our hypothesis that complete recovery of the reproductive system following molting involves complex tissue remodeling that is reversible and involves specific changes in gene expression and molecular aspects. In order to identify candidate genes that potentially regulate oviduct regression or tissue remodeling, we established the chicken in vivo model for induced molting and post-molting recrudescence. For induction of molting, we fed hens a diet enriched in zinc as previously reported, which led to complete cessation of egg production within 12 days. After the complete cessation of egg production, molted hens were removed from the high zinc diets and they resumed egg production within 23 days, which is similar to results Y-27632 reported by Scott et al.. Along with changes in egg production, dramatic regression of oviducts and ovaries occurred in response to the high zinc diet, but this was followed by recrudescence after the hens were returned to a normal diet. Weights of the whole body and reproductive organs, as well as length of the oviduct were measured, all of which showed similar V-shaped patterns. The change in overall body weight is BU 4061T directly associated with in weights of liver, muscle, adipose tissue, and involution of reproductive tissues. The extent of body loss during molting is a key factor for successful post-molting improvements in egg quality and egg production. The decreases and gains in ovarian and oviductal weights may be related to the overall rejuvenation of the hen associated with increases in metabolic processes of many tissues. The overall regeneration processes included recovery of atretic follicles, release of egg 
yolk materials and ovarian steroids, and increases in weights of reproductive tissues, as well as cellular and tissue morphology.