Previous experiments have established a relationship between the morph
ological characteristics of human spermatozoa and their fertilizing po
tential 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; an
d group C (n = 31), >14% normal morphology. Morphology slides were pre
pared using Diff Quik staining techniques and evaluated by Kruger stri
ct criteria, under oil immersion, at a magnification of x1000; specifi
c defects, viz. head, neck, cytoplasmic droplets, tail, immature cells
, were assessed individually. Following PGC, a sperm sample with enhan
ced morphology was recovered for groups B (P < 0.01) and C (P < 0.005)
; however, for group A (very severe teratozoospermia) PGC did not sele
ct a sample with significantly improved morphological quality. Specifi
c sperm defects affected by PGC were head, neck and immature cells. No
significant difference was found for tail abnormalities or cytoplasmi
c fragments.