Development-promoting effect of chicken embryo membrane on chicken ovarian cortical pieces of different age

Ovarian cortical tissues of various ages of chicken were grafted underneath chorioallantoic membrane (CAM) of 6-d-old chicken embryo and the grafts were collected on d 0, 2, 4, 8, or 10. The tissue sections were prepared to examine the development of follicles in grafts and the proliferative ability of follicles was examined by immunohistochemistry analysis of proliferating cell nuclear antigen. The results indicated that the development of follicles in cultured chicken ovarian cortical pieces progressed smoothly and slowly similar to those in vivo, and the environment of chicken embryo was more suitable for the synchronous development of oocyte and follicular cells in the larger follicles. Meanwhile, the synchronous development could be more easily achieved in the chicken ovarian tissues of 12- to 15-wk chicken. Neither oocyte nor granulosa cells but the thecal cells of follicles developed in grafts of 13- to 15-d chicken within 10 d of culturing in ovo, and the CAM can ease follicular atresia in chicken ovarian grafts of 12- to 15-wk chicken. The proliferative performance of follicles in the grafts was not influenced by the environment of chicken embryo. These results indicated that the chicken embryo has the ability to support slow development of primordial and primary follicles in grafted ovarian cortical tissues of chickens of different ages. The CAM system may also prove useful for the study of early follicle development with further information.