The Relationship Between Sperm Head Retardance Using Polarized Light Microscopy and Clinical Outcomes

Abstract

Sperm heads exhibit birefringence when examined with polarized light microscopy as a result of visualization of highly ordered structures within the acrosome and nucleus. DNA damage in sperm can be positively correlated with increased sperm head retardance. Polarized light microscopy has been used to assess sperm quality prior to intracytoplasmic sperm injection (ICSI). Selecting sperm with partial birefringence under polarized light identifies a normal sperm structure as well as DNA integrity and improves success of clinical pregnancies in patients with severe male factor infertility. Previous studies suggest a possible optimum range of retardance in sperm heads that reflects partial birefringence and DNA integrity of single sperm.This study was designed to establish a range of retardance in sperm heads examined under polarized light microscopy to select an optimum sperm prior to ICSI. At the time of ICSI, individual sperm heads of 63 couples undergoing ICSI in women 38 years or younger were imaged and saved. The images were later analyzed for retardance blinded to embryo and cycle outcomes.Fertilization rates were not related to sperm head retardance (ie, sperm head retardance was similar whether fertilization occurred). The best-quality embryos on days 3 and 5 were obtained from selection of sperm with head retardance ranging from 0.56 nm or greater to 0.91 nm or less. The likelihood of a clinical pregnancy occurring when sperm head retardance was within this range was high; the odds ratio was 3.74, with a 95% confidence interval, 1.43-9.77; P = 0.007.These data show for the first time that sperm head retardance between 0.56 and 0.91 nm is associated with optimal embryo quality, development, and clinical pregnancy rates. Measuring retardance appears to be a reproducible and reliable technique to increase embryo quality and clinical pregnancy rates.

Improving ICSI: A review from the spermatozoon perspective

“…Moreover, Petersen and colleagues concluded in their study that there is a positive correlation between the sperm head's birefringence and DNA fragmentation [Petersen et al 2011]. The results of a recent study by Vermey and colleagues support the results of Gianaroli's group, indicating that when sperm cells were selected based on their birefringence, a higher fertilization rate and embryo quality could be expected [Vermey et al 2015].…”

Selecting motile, non‐apoptotic and induced spermatozoa for capacitation without centrifuging by MACS‐Up method

“…Also, increasing the intracellular level of calcium ions as a second messenger and activating the chemotaxis signalling with cyclic nucleotide analogs are considered as another possible progesterone pathway to induce sperm capacitation (Teves et al, 2009). Induction and augmentation of sperm capacitation can increase the fertilization rate in ART, especially in ICSI procedure (Nasr‐Esfahani et al, 2012; Vermey et al, 2015).…”