Infertility, commonly referred to as sterility in everyday language, is defined as the inability of a couple to conceive after one year of unprotected intercourse. Around 25–30% of infertility cases are due to male factors. In approximately 10% of male factor infertility cases, no mature sperm is found in the ejaculate, a condition medically referred to as azoospermia. About 0.8–1% of men are azoospermic. In most of these patients, the cause is a disorder in sperm production. Rare chromosomal abnormalities should be screened, hormonal tests performed, and if no problems are detected in these tests, TESE (Testicular Sperm Extraction) should be carried out, which involves surgically retrieving testicular tissue to isolate sperm. Studies have shown that in appropriate patients, sperm can be retrieved in 43.7% of TESE procedures. In our clinic, this rate reaches 65–70% with the micro-TESE technique. For patients in whom mature sperm cannot be found even after two TESE attempts, we use a method called ROSI—short for Round Spermatid Injection—which involves using round spermatids, immature precursor sperm cells.
The earliest precursor cells, primordial germ cells, undergo mitosis to form spermatogonia, which in turn undergo further mitosis to become primary spermatocytes. These three precursor cell groups all contain 46 chromosomes and lack the ability to fertilize an egg. Primary spermatocytes then undergo the first meiotic division, reducing their genetic material by half to form secondary spermatocytes with 23 chromosomes. A second meiotic division occurs, producing immature precursor cells known as round spermatids. Round spermatids are the stage just before mature sperm cells and have not yet undergone metamorphosis, the process of structural maturation.
In 30% of TESE specimens from patients with sperm production disorders, round spermatids have been found. This means that even in cases where no mature sperm can be retrieved via TESE, approximately 30% of patients may still achieve pregnancy using the ROSI method. Moreover, pregnancies and children obtained through this method have shown outcomes as healthy as those achieved with normal sperm cells. At Cyprus American IVF Center, with our specialized and experienced Clinical Embryology team, we successfully perform the ROSI technique with high success rates.
