Electron microscopic study of the chorioallantoic placenta of the rock hyrax (Heterohyrax brucei).

The interhaemal membrane consisted of only two cellular elements: a single layer of cellular trophoblast and the fetal capillary endothelium. The hyrax is therefore one of the few mammals known to possess the cellular haemomonochorial type of placenta. The trophospongium was also cellular while the basal trophoblastic cells were strongly phagocytic.

Plasma vitamin B12 and reproductive performance of cows on cobalt-deficient pastures in the Rift Valley of Kenya.

Plasma vitamin B12 and glucose in beef and dairy cattle were determined in a well-managed and poorly-managed farm in the cobalt-deficient pastures of the Naivasha area of the Rift Valley of Kenya. These values were compared to those obtained in a well-managed farm from cobalt-replete pastures outside the Rift Valley. Whilst plasma vitamin B12 from the well-managed farm in the Rift Valley (371 +/- 20 pg/ml) were comparable to those from the cobalt-replete pastures (288 +/- 19 pg/ml), those from the poorly-managed farm were significantly lower (156 +/- 13 pg/ml, P less than 0.

Influence of ruminal insufflation on pulmonary function and diaphragmatic electromyography in cattle.

In 8 healthy, awake cows with permanent cannulated ruminal fistulas and carotid artery loops, respiratory mechanics, ventilation, and diaphragmatic electrical activity were studied before and during stepwise insufflation of the rumen with air pressure to 40 mm of Hg. We found that ruminal insufflation increased intraperitoneal, intrapleural, and transdiaphragmatic pressures and decreased lung volume and lung compliance. In individual cows with rumen insufflation there was an increase in pulmonary resistance, but this trend was not significant in the group.