THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

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aspiration procedure vras repeated for the coilection of the amnlotic
fluid. At the earìy stages of pregnancy, fetal cord bJood was obtained
from the umbilicat cord(vein), whereas during the later stages,
fetal blood was obta{ned by heart puncture.
3lood sampres were coflected, either with or without added
antlcoagulant. Upon withdrawl , the blood was .inmediatety chiìled in
ice, centrifuged at 4 C within 2 h, and 3 ml aliquots of plasma or
serun were frozen and stored in stoppered glass via.ls at -20 C.
For oPL determination, a 3 ml aliquot was thawed at room temperature,
samples stored for as long as 2 years showed no apparent loss of
oPL content.
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cotyledons at varlous dais of gestation
Placentomes were co.l iected from ewes sacrificed at various
days of gestation, The maternal caruncìes were separated frorn the
feta'l membrane (fetaì cotyledons plus fetaì i ntercotyr edonary membranes )
until day 40, but , subsequently, no separation was carried out between
maternal caruncles and fetar cotyledons. As soon as the tissues were
co'llected, they were inrnediately frozen over solid carbon dioxide,
sea'led in plastic bags, and stored at _20 C until use.
For deternination of opl concentration in the tissues, the
pìacental tissues were weighed, homogenjzed wjth 0.'ll"t armonium bicar-
bonate buffer, pH 8.2 at 4 c with a trssue to buifer ratio of l:S