Tl. Ott et al., EFFECTS OF STAGE OF GESTATION AND UTERINE LIGATION ON OVINE PLACENTOME DEVELOPMENT AND GLYCOSAMINOGLYCANS, Journal of animal science, 75(4), 1997, pp. 1053-1062
Effects of restricting uterine space on physical, biochemical, and his
tochemical characteristics of ovine placental tissues were studied. Ew
es (n = 20) were unilaterally ovariectomized, assigned to either contr
ol(C; n = 10) dr unilateral (UPx; n = 10) pregnancy groups, mated (d 0
), and hysterectomized on either d 60, 90, or 120. Placental and fetal
weights and placentome wet weights (PWT) in three placental areas (AI
, AII, AIII) were recorded. Placentome tissue concentrations of RNA, D
NA, hyaluronic acid (HA), and protein (TP) were determined. Overall, p
lacentome numbers were reduced (P < .02) 23%, but individual PWT incre
ased (P < .05) 27% in UPx ewes. In UPx ewes, neither total placental n
or placentome weights, fetal weights, fetal crown-rump lengths, nor PW
T:fetal weight ratios were affected by treatment (Trt). In the C and U
Px groups, PWT increased (P < .01) from d 60 to 90. However, compensat
ory growth was confined to placental areas AII and AIII in UPx groups
(treatment x area, P < .01). Treatment did not affect concentrations o
f RNA, DNA, TP, or HA. However, RNA, DNA, and TP increased from d 60 t
o 120 (P < .01), but HA decreased (P < .01). Histologically, placentom
e cellularity increased from d 60 to 120 as area occupied by-individua
l fetal chorioallantoic villi (FV) decreased. The FV stained with Alci
an Blue 8X. Alcianophilia was attenuated at low pH and eliminated by p
retreatment with hyaluronidase, indicating the presence of HA. Thus, i
ncreased placentomal cellularity was accompanied by loss of HA from fe
tal allantoic mesenchyme. Mechanisms regulating loss of HA from EV may
support placental maturation and fetal growth.