Abstract: 475

VASCULARIZATION IN THE TAMMAR WALLABY UTERUS DURING PREGNANCY: A ROLE FOR VASCULAR ENDOTHELIAL GROWTH FACTOR.

James N Ingram¹ , Laura J Parry^{1 *}
Department of Zoology, University of Melbourne, Parkville, Victoria, AUSTRALIA ¹

Successful implantation and placentation require expansion of the endometrial vascular bed and placental angiogenesis, processes thought to be regulated by the angiogenic peptide, vascular endothelial growth factor (VEGF). Expression of VEGF in the uterus is induced by oestrogen but may also be regulated by the fetus. Such feto-maternal influences can be investigated in the monovular tammar wallaby as it has two anatomically separate uteri. Thus, during pregnancy, the gravid uterus contains a single fetus whereas the contralateral uterus remains nongravid. Our aims were to examine vascularization in both uteri during pregnancy and assess production of VEGF. There is a significant proliferation of blood vessels in the endometrial epithelium between Days 22-23 of the 26-day gestation, particularly in regions underlying the trilaminar (vascular) yolk sac placenta. No increase in vascularization occurs in the nongravid uterus. To investigate production of VEGF, we first obtained a 550bp fragment of the tammar VEGF cDNA molecule using RT-PCR and combinations of oligonucleotide primers from highly conserved regions of known VEGF cDNA sequences. This fragment includes 495 nucleotides which code for the 165 amino acid variant of the predominant isoform in other species. Three VEGF gene transcripts are expressed in the tammar placenta and endometrium with VEGF(165) as the dominant isoform. Gene expression is highest in the gravid endometrium between Days 20-23 of pregnancy. Immunoreactive VEGF is also present in the endometrial epithelium in the gravid uterus, in close proximity to endothelial cells surrounding the capillaries. Our data show increased production of VEGF in the gravid uterus which coincides with the onset of vascularization in the endometrium.

    This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.