HUMAN SPERM MORPHOLOGY EVALUATION PRE-PERCOLL AND POST-PERCOLL GRADIENT CENTRIFUGATION

Previous experiments have established a relationship between the morphological characteristics of human spermatozoa and their fertilizing potential in vitro. To assess further the efficiency of Percoll gradient centrifugation (PGC) as a method of sperm selection, we have examined morphological characteristics of spermatozoa from 86 teratozoospermic patients attending Nottingham University Research and Treatment Unit in Reproduction (NURTURE). Patients were divided into groups according to percentage normal morphology in the fresh sample: group A (n = 14), <5% normal morphology; group B (n = 41), 5-14% normal morphology; and group C (n = 31), >14% normal morphology. Morphology slides were prepared using Diff Quik staining techniques and evaluated by Kruger strict criteria, under oil immersion, at a magnification of x1000; specific defects, viz. head, neck, cytoplasmic droplets, tail, immature cells, were assessed individually. Following PGC, a sperm sample with enhanced morphology was recovered for groups B (P < 0.01) and C (P < 0.005); however, for group A (very severe teratozoospermia) PGC did not select a sample with significantly improved morphological quality. Specific sperm defects affected by PGC were head, neck and immature cells. No significant difference was found for tail abnormalities or cytoplasmic fragments.