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An acute phase response was previously found in cows at parturition, which might be associated with uterine cytokine release. Five late pregnant cows were implanted with vascular catheters in both the maternal aorta and uterine vein. Blood samples were taken to study temporal relationships between changing plasma levels of proinflammatory cytokines and the periparturient acute phase response following prostaglandin (PG)-induced luteolysis at Day 275 of gestation. The plasma levels of three proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6), as well as progesterone (P4), PGFM and serum amyloid A (SAA) were measured every 4 h between PG induction and expulsion of the calf. In the arterial plasma, progesterone levels dropped to baseline levels within 10 h following PG treatment, indicative of complete luteolysis. Contrary to expectations, the uterine vein samples showed lower proinflammatory cytokine levels compared with the maternal aorta values. A classical acute phase response, as assessed by SAA, was observed during the expulsive stage, but not during luteolysis.

A cold microwave irradiation procedure was developed to fix rapidly and stain various tissues and monolayers for electron microscopy. Because microwave stimulation always produces some heat, melting ice was used to maintain the temperature of the tissue samples, the fixative, and the staining solution at 0 to 4 degrees C. The low temperature also reduced vapour formation, thus minimizing the risk of explosion. The microwave method shortened the total time of fixation and dehydration from the usual 3 h required by the conventional method to 65 min. After microwave fixation, the ultrastructural details of membranes and subcellular structures were excellent.