Monitoring preantral follicle survival and growth in bovine ovarian biopsies by repeated use of neutral red and cultured in vitro under low and high oxygen tension.

The development and optimization of preantral follicle culture methods are crucial in fertility preservation strategies. As preantral follicle dynamics are usually assessed by various invasive techniques, the need for alternative noninvasive evaluation tools exists. Recently, neutral red (NR) was put forward to visualize preantral follicles in situ within ovarian cortical fragments.