Time-course of the uterine response to estradiol-17beta in ovariectomized ewes: uterine growth and microvascular development.
The time-course of uterine growth, cell proliferation, and microvascular development was evaluated during the first 72 h after implanting estradiol-17beta (E2) into ovariectomized (OVX) ewes. Uterine fresh weight increased 2.3-fold by 24 h and increased further (3.3-fold) by 48 h. The majority (approximately 75%) of this growth response was associated with tissue growth rather than a change in the tissue dry weight:fresh weight ratio. Both uterine cell number (DNA content) and cell size (RNA:DNA ratio) increased from 0 to 24 h (1.8-fold and 1.7-fold, respectively). Cell proliferation also increased dramatically between 8 h and 24 h after E2 implantation. Endometrial microvascular volume density (percentage of tissue volume occupied by microvessels) increased approximately 1.8-fold by 24 h and then remained constant or declined slightly through 72 h. The total endometrial microvascular volume, however, increased approximately 5-fold from 0 to 24 h and increased further by 72 h. Thus, treatment of OVX ewes with E2 caused a dramatic increase in uterine fresh and dry weights by 24 h, due primarily to hyperplasia and hypertrophy, with only a relatively small change in tissue dry weight:fresh weight ratio. This dramatic uterine growth was associated with a profound increase in endometrial microvascular volume.
Department of Animal & Range Sciences, North Dakota State University, Fargo, 58105, USA. lreynold@prairie.nodak.edu
L P
LP
Reynolds
J D
JD
Kirsch
K C
KC
Kraft
D L
DL
Knutson
W J
WJ
McClaflin
D A
DA
Redmer
D000818:Animals; D002452:Cell Count; D048429:Cell Size; D004247:DNA / Q000032:analysis; D004343:Drug Implants; D004717:Endometrium / Q000098:blood supply; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008833:Microcirculation / Q000254:growth & development*; D009929:Organ Size; D010052:Ovariectomy; D012313:RNA / Q000032:analysis; D012756:Sheep / Q000502:physiology*; D014599:Uterus / Q000098:blood supply* / Q000187:drug effects / Q000254:growth & development*
D004343:Drug Implants; D004958:Estradiol; D012313:RNA; D004247:DNA