Quantification, morphology, and viability of equine preantral follicles obtained via the Biopsy Pick-Up method.

The research tests a method known as Biopsy Pick-Up (BPU) to extract preantral follicles from the ovaries of mares. It established that the method is efficient in collecting samples without negative impacts on the mare’s health or reproduction.

Experiment Execution

• The study was conducted on 18 mares, ranging between 5-21 years of age during the breeding season. The health status of the mares was monitored consistently throughout the experiment.
• An ovarian biopsy was performed on the mares either during their estrous or diestrous phase, which was confirmed by using transrectal ultrasonography.
• Preantral follicles were isolated through a mechanical process with a tissue chopper. Post the isolation, these follicles were quantified and labeled as either normal or abnormal and primordial (undeveloped) or primary (developed).
• The viability of these isolated follicles was examined using Trypan Blue dye. A total of 256 biopsy attempts resulted in a successful retrieval of 185 tissue samples, positioning the success rate of obtaining samples at 72%.

Findings

• Overall, the researchers managed to isolate 620 preantral follicles, with 95% classified as primordial and 5% as primary.
• An average of 18.8 follicles was isolated per biopsy procedure. Primordial follicles had an average diameter of 31.3 μm and primary follicles measured an average of 41.1 μm.
• In the evaluation of viability, primordial follicles exhibited a higher rate (91%) compared to primary follicles (50%). They also displayed a higher rate of morphological normality (96%) versus primary follicles (80%).
• The phase of the estrous cycle did not influence the number of follicles isolated, the amount of tissue harvested, and the number of follicles per mg of tissue.
• Younger mares yielded a higher number of follicles isolated per procedure than older mares. However, the length of the interovulatory interval was not affected by the biopsy procedure.

Outcomes

• The BPU method proved to be effective and efficient in acquiring viable preantral follicles without any harmful effects on the mare’s reproductive cycle or overall health.
• In the future, the BPU method could serve as an important tool in obtaining preantral follicles for culture in a laboratory setting. This right to usage of numerous oocytes present within the equine ovary can potentially lead to genetic material preservation or large-scale embryo production.