Characterization of the expression of the alternative splicing of the ED-A, ED-B and V regions of fibronectin mRNA in bovine ovarian follicles and corpora lutea

Fibronectin is an extracellular matrix glycoprotein. Alternative splicing o f fibronectin mRNA within three specific regions, the extra domains (ED) A and B and the variable (V) or IIICS region, result in the production of dif ferent isoforms of fibronectin. These isoforms differentially regulate tiss ue developmental processes, such as those occurring during follicular and l uteal development. The specific isoforms of fibronectin present in follicle s and corpora lutea have not been identified. To identify these, primers fo r reverse transcription polymerase chain reaction (RT-PCR) were designed to the known bovine amino acid sequence of exons flanking the ED-A, ED-B and V regions. PCR products from bovine fetal liver cDNA were determined to be bovine fibronectin by the correct product size and DNA sequence homology to other species, and to the known bovine amino acid sequence. Bovine ovarian follicles (0.5-9 mm diameter) and corpora lutea (cyclic, early to late mid -luteal phase) were shown to express ED-A+, ED-A-, ED-B+, ED-B-, V+ and V- fibronectin isoforms, similar to the liver, lung and kidney of fetuses, but generally not of adult animals. Thus follicles and corpora lutea express i soforms of fibronectin usually expressed in developing tissues.