Characterization of Oviduct Lining, with Emphasis on the Sperm Storage Tubule Region (Uterovaginal Junction), Correlated with Fertility in Mature and Old Thai Native Hens

SIMPLE SUMMARY: Although a reduction in the number of sperm in the sperm storage tubule (SST) regions in older hens was hypothesized to relate to fertility, no comparison has been made to date on the effect of age (mature and old) on reproduction, the morphology of the sperm storage reservoir, the resident sperm in the UVJ, and the fertility duration in chickens. The present study indicated the morphological characteristics of reproductive organs did not differ between mature and old hens. The numbers of ovarian follicles were greater in mature hens. Significant differences in the sperm storage reservoir, such as the inner and outer diameter of the SSTs and epithelium height, were demonstrated. The number of resident sperm cells that were related to fertility periods was greater in mature hens than in old hens. ABSTRACT: The effect of age on fertility was investigated in Thai native chickens. The objective of this study was to determine the effects of age (mature and old) on the morphological characteristics of the reproductive organs and the histological characteristics of the uterovaginal junction (UVJ) tissues, resident sperm in the UVJ, and fertility duration in Thai native hens. We found no differences in the morphological characteristics of the reproductive organs, except for the number of follicles and the sizes of the fifth large yellow follicle in mature hens, which were greater than those in old hens (p < 0.05). The diameter of the sperm storage tubules (SSTs) epithelium was larger in old hens than in mature hens (p < 0.05), whereas the epithelium height was lower in old hens (p < 0.05). The number of sperm in the SSTs was greater in mature hens compared with old hens (p < 0.05). Mature hens showed a higher fertility rate than old hens. Our results suggest that, in old hens, the function of the SSTs is impaired, and sperm cannot be retained. Such a deterioration of the SSTs may be one of the factors involved in the decline in fertility.