The mammalian endometrium undergoes a remarkable series of developmental changes during the

sexual cycle, in preparation for implantation, and these changes persist into early pregnancy. The

phenomena of cyclic endometrial remodelling, implantation, gestation, and parturition may require

specific cell to cell and cell to stromal matrix interactions. The interaction between the cell and

substratum is mediated by several classes of cell adhesion molecules, one of the most important

being the integrins. Although the specificity of integrins is known to differ between human

endometrial stromal cells and decidual cells, no information is available on the distribution of the

fibronectin receptor (Integrin p i) and laminin protein in the female reproductive tract of the bitch

during the estrous cycle. In this study, the presence of the fibronectin receptor (Integrin p i) and

laminin, and the cyclic changes observed in their distribution in the bitch uterus were determined

for the first time during the estrous cycle, which is a preparatory stage for implantation. The tissue

samples used in this study were taken from 15 healthy bitches, including 5 animals each in the

different phases of the estrous cycle, which were aged 3-7 years, of different breeds and had been

admitted to private veterinary clinics in the Kayseri province for routine ovariohysterectomy. It was determined that, the fibronectin receptor (Integrin pi) was localized to the surface, crypt and

glandular epithelial cells of the endometrium, the stromal cells, blood vessels, myometrium,

perimetrium and peritoneal mesothelial cells in the bitch uterus. In the bitch uterus, the fibronectin

receptor (Integrin p i) displayed a positive immunoreaction at all phases of the estrous cycle in the

endometrium, myometrium and perimetrium. It was observed that, in general, laminin was located

in the extracellular matrix surrounding the muscle cells, blood vessels and connective tissue cells,

and in the basal membranes. The fibronectin receptor (Integrin p i) and laminin were found to be

present at high levels in the endometrium of the bitch uterus at the luteal phase. The results of the

present study will contribute to the understanding of the underlying reasons of ovulation,

implantation and embryonic development problems encountered in bitches, the clinical use of the

laminin and fibronectin molecules for the treatment of reproductive disorders, and the

interpretation of the implantation stage, which is the most important stage of reproduction.