Microarray technology provides new insights into the field of reproductive biology as well as other fields of medicine and biology. We fabricated a bovine uteroplacental cDNA microarray and investigated the key factors involved in the establishment and maintenance of gestation. Microarray-based global gene expression analyses on bovine placenta and trophoblast cells suggest that the expression profiles of specific genes depend on the cells and tissues in which they are expressed as well as the time of the gestation period. This custom-made microarray revealed that trophoblast-specific genes such as placental lactogen, pregnancy-associated glycoproteins, prolactin-related proteins, and those of the sulfotransferase family were mainly expressed in the trophoblast giant cells and that their expression increased as gestation progressed. The expression of these genes was extremely temporal and spatial. Further, the expression of the transcription factor AP-2 increased in the trophoblast giant cells as gestation progressed. Thus, the AP-2 gene family may play a major role in regulating the functions of bovine trophoblast giant cells. Microarray technology provides information not only on thousands of genes simultaneously but also on their regulatory mechanisms in cells. Bioinformatic tools could greatly aid biological and biomedical research; therefore, active efforts must be undertaken in this field.