Changes in urinary flow in bovine fetuses during late gestation: composition of amniotic and fetal body fluids
Reeves, J.T.; Daoud, F.S.; Gentry, M.; Eastin, C.
American Journal of Veterinary Research 33(11): 2159-2167
1972
ISSN/ISBN: 0002-9645 PMID: 5081475 Document Number: 49551
In the bovine foetus urine can flow through the urethra into amniotic fluid or through the urachus into the allantoic fluid. The purpose in the present experiment was to determine whether the direction or urinary flow from the bladder changed late in gestation. Samples of maternal and foetal blood and foetal fluids were collected during caesarean section in 35 Jersey cows in which the duration of pregnancy varied from 163 to 281 days (term). The high urinary concentrations of sugar, urea, uric acid, and phosphate and the low urinary concentrations of chloride were useful indicators of the probable direction of urine flow. In foetuses older that 240 days, the concentrations of sugar, urea, phosphate, and uric acid increased in the amniotic fluid, but the concentrations of chloride decreased. Thus, the concentrations of these substances in amniotic fluid came to resemble more nearly those in urine. The concentrations of sugar in allantoic fluid decreased late in gestation, and the concentrations of the other solutes did not change. This shows that urine preferentially entered the amniotic fluid in bovine foetuses near term. Changes occurred despite the persistent patency of the urachus.