Question

List the application of IntraCytoplasmic Sperm Injection (ICSI) and Round Spermatid Injection (ROSI) in Assisted Reproductive Biotechnology. At least 5 applications for each of them.

Answer 1

The application of ICSI to mammals now includes widespread use in research, particularly in the mouse, and in human assisted reproduction. Because ICSI bypasses facets of fertilization that are upstream of sperm–oocyte union, this technique has been adapted in the mouse for genome manipulation, the delivery of non-sperm nuclei into oocytes (e.g., somatic cell nuclear transfer) and to dissect totipotency.

• ICSI is recommended when all other techniques of assisted reproduction fail. It is a method of choice to obtain monospermic zygotes if IVF fails to produce fertilized oocytes

• ICSI has become a useful technology in cases when semen availability is less e.g. if semen is sex sorted18

• Semen collected from deceased animal. Epididymal sperms can be collected and used via ICSI if a genetically superior male dies

• Sub-fertility related to abnormalities in ejaculated semen e.g., oligozoospermia (low sperm concentration), teratozoospermia (sperms with abnormal morphology), asthenozoospermia (sperms with reduced motility), necrozoospermia (Dead spermatozoa)

• Azoospermia i.e., No sperms in ejaculate. It may be obstructive or non-obstructive. In such cases, ICSI may be combined with epididymal or testicular sperm retrieval

• Presence of antisperm antibodies

• Ejaculatory disorders

• Congenital (cystic fibrosis or unilateral renal agenesis leading to congenital absence of vas deferens) or acquired abnormalities (fibrosis) of reproductive tract

• Transgenic animal production

• Conservation of endangered species

Round spermatids, which are immature precursors to mature spermatozoa, can be successfully injected into human oocytes and used in place of mature spermatozoa in cases of last resort. Among men with spermatogenic failure where neither mature spermatozoa nor late-stage spermatids were isolated from testicular samples, 30% of patients were found to possess round spermatids in their surgical samples. In both animal and human models, successful births have been reported using the technique of round spermatid injection (ROSI). Although early reports described ROSI as inefficient and of no clinical value, recent studies have reported ROSI to be a feasible alternative in patients who decline donor sperm. Importantly, ROSI appears to result in offspring without any unusual physical, mental, or epigenetic problems. Most recently, a publication by Tanaka et al. in 2018 reported the births of 90 babies following ROSI and followed the offspring for two years to track physical and cognitive development. No significant differences were observed between offspring achieved via ROSI compared to spontaneous conceptions over the two year observational period.