Histological characteristics of follicles and reproductive hormone secretion during ovarian follicle development in laying geese

Egg production in different goose breeds vary significantly, which is related with the physiology of reproduction. However, the knowledge of physiology of goose reproduction is not well documented. In the present study, the 3 breeds with significantly different egg production were selected to investigate the histological characteristics of follicles and reproductive hormone secretion during follicle development, which included Carlos geese (Anser anser), Zhejiang geese (Anser cygnoides), and Yangzhou geese (Anser cygnoides). The results indicated that there were significant differences in the morphology of ovary and follicles among different goose breeds. The mode of hierarchical follicles in Yangzhou geese was 5, and those were 3 and 4 in Zhejiang and Carlos geese, respectively. The numbers of prehierarchical follicles were 61 to 70, 69 to 75, and 28 to 39 in Yangzhou geese, Zhejiang geese, and Carlos geese, respectively. The thickness of granulosa layer of follicles was higher in the large yellow follicle than those in the other prehierarchical and hierarchical follicles, and Yangzhou geese were the highest among the 3 breeds. The concentration of follicle stimulating hormone (FSH) ranged from 12.17 to 28.06 U/L, and 17 beta-Estradiol ranged from 27.01 to 49.39 pmol/L by the enzyme-linked immuno sorbent assay. The level of FSH of Yangzhou geese reached to the highest in the hierarchical follicle (F1), while the other 2 geese did not show the similar feature. In addition, the level of luteinizing hormone (LH) and progesterone (PROG) in the prehierarchical follicles of Yangzhou geese was higher than those in Carlos and Zhejiang geese. In summary, the difference of histological characteristics of follicles and reproductive hormone in different goose breeds was not only reflected in the number of follicles and the thickness of the granulose cell layer, but also embodied the secretion LH and PROG. The more thickness of the granulose cell layer and high secretions of LH and PROG contributed to the development of prehierarchical follicles to hierarchical follicles, which may be due to the fact that Yangzhou geese (Anser cygnoides) has more egg production.