Ke. Hehnke et al., MACROPHAGE INFILTRATION INTO THE PORCINE CORPUS-LUTEUM DURING PROSTAGLANDIN F-2-ALPHA-INDUCED LUTEOLYSIS, Biology of reproduction, 50(1), 1994, pp. 10-15
Although it has been reported that the number of macrophages increases
in the pig CL at the time of luteolysis, the temporal association bet
ween this infiltration and the sequence of events involved in luteolys
is has not been established. In the current study, single CL on an ova
ry of estrogen-treated pseudopregnant gilts were induced to undergo lu
teolysis after the introduction of prostaglandin F-2alpha (PGF)-impreg
nated silastic implants on Day 13 (Day 0 = first day of estrus). Other
CL on the same ovary were treated with implant material only (vehicle
-implanted) or left unimplanted. At 6, 12, and 24 h after implant plac
ement, CL were removed and progesterone concentrations as well as the
number and location of macrophages within each CL were determined. Pro
gesterone concentrations declined significantly (p < 0.05) by 12 and 2
4 h postimplantation in PGF-treated CL but not in vehicle-implanted or
unimplanted CL. There was a significant influx (p < 0.05) of macropha
ges at 6 h in all implanted CL (PGF or vehicle-implanted) as compared
with unimplanted CL. In PGF-treated CL, macrophage numbers progressive
ly increased through 24 h. In contrast, although a macrophage influx a
lso occurred in vehicle-implanted CL at 6 h, macrophage numbers progre
ssively declined through 24 h. The simplest explanation for these data
is that the initial rise in macrophage numbers at 6 h after Ct implan
tation is a result of the implantation procedure itself. Further, the
observation that most of the influx of macrophages occurred after the
decrease in progesterone concentration in PGF-treated CL is consistent
with their role in phagocytosis of cellular debris.