Tissues were obtained from 16 Angus and Hereford cows from the US Subtropical Agricultural Research Station, Brooksville, FL. Breeding dates were known for some of the cows; in the others, length of gestation was determined from fetal crown-rump length. Samples were obtained at the following gestational ages: 150 days, 275 days, at term not in labor (designated 280- days), at term in labor (designated 280+ days), and 6-12 h postpartum. Additionally, six third-trimester Angus-Brahman crossbred cows were obtained from the Beef Research Unit, Animal Science Department, Gainesville, FL, for study of the effect of OT on COX-2 expression in intercaruncular endometrium. flovent inhaler
The gestational ages of these cows were between 230 and 270 days at the time of the experiment. Tissues were collected at the Meats Laboratory of the University of Florida after exsanguination. All tissues were placed on ice, cut free from adnexa as quickly as possible, frozen in liquid nitrogen, and stored at -75°C until processed for total RNA extraction. All procedures were approved by the Institutional Animal Care and Use Committee.