Adhesion molecules and matrix proteins on human spermatozoa

Ejaculated spermatozoa and spermatogenic cells express alpha- and beta-chains of beta 1, 3 and 4 integrins as well as their ligands fibronectin and laminin in an extended intra- and interindividual variation and in different patterns of location. The mRNA transcripts of these molecules were detectable by nested polymerase chain reaction in the spermatozoa. The conclusion of a functional competence of these adhesion molecules (AM) was supported by their relation to the results of the zona-free hamster oocyte penetration (HOP) test, the in vitro fertilization of human oocytes and cell attachment assays. AM labelling was influenced by the disintegration of the sperm plasma membrane, especially in seminal plasma, by progesterone, human follicular fluid and microorganisms, but was barely modified by sperm cryopreservation. Despite substantial advances in the knowledge about sperm adhesion molecules, many questions remain to be answered.