Adhesion molecules in reproduction

The integrin adhesion molecules are transmembrane glycoproteins with a heterodimeric structure. They are able to recognise cell surface receptors and extracellular matrix glycoproteins. Integrins are involved in all three phases of reproduction: fertilisation, implantation and placental development. In sperm-egg interaction, integrins participate in the sperm-ooplasmic membrane recognition and fusion. The embryo and the endometrium use the language of integrins for the early stages of communication. Aberrant expression of integrins by endometrium is associated with an adverse effect on blastocyst implantation. Most of the studies investigating the involvement of integrins in reproduction are observational. More information may be derived using 'knockout' techniques involving either genes or gene products (proteins). Although these techniques are associated with technical and ethical problems, exciting new developments lie ahead.