Influence of the ovarian fragmentation before storage at 4oC on the apoptosis rates and in vitro development of ovine preantral follicles

The aim of this study was to evaluate the effect of ovarian tissue fragmentation before preservation at 4 o C in MEM on the morphology, apoptosis, and growth of ovine preantral follicles. After collection, the ovaries were divided into two halves, being one divided into two fragments (1/4 of the ovary). One fragment was subdivided into two fragments (1/8), being one fixed for histology (fresh control). The remaining whole ovary, 1/2, 1/4 and 1/8 of the ovary were preserved in MEM at 4C for 6, 12 or 24 h. The tissue was further destined to histology. In vitro culture and TUNEL technique were performed in treatments that showed the best results of follicular survival after preservation. Storage of 1/8 of the ovary increased the normal follicles compared with half or whole ovary. After preservation in 1/8 of the ovary and culture for 7 days, the percentage of apoptotic cells was similar to the fresh control and non-cultured fragments. The percentage of growing follicles increased after preservation of 1/8 of the ovary compared with 1/4. In conclusion, ovine preantral follicles can be preserved in fragments of 1/8 of the ovary in MEM at 4C for 24 h, without affecting apoptosis and their ability to grow in vitro.