Equine hydrallantois is associated with impaired angiogenesis in the placenta

Pouya Dini, Mariano Carossino, Alan T. Loynachan, Hossam El-Sheikh Ali, Karen E. Wolfsdorf, Kirsten E. Scoggin, Peter Daels, Barry A. Ball

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Introduction: Hydrallantois is the excessive accumulation of fluid in the allantoic cavities during the last trimester of pregnancy, leading to abdominal wall hernias, cardiovascular shock, abortion, and dystocia. It has been postulated that hydrallantois is associated with structural and/or functional changes in the chorioallantoic membrane. In the present study, we hypothesized that angiogenesis is impaired in the hydrallantoic placenta. Method: Capillary density in the hydrallantoic placenta was evaluated in the chorioallantois via immunohistochemistry for Von Willebrand Factor. Moreover, the expression of angiogenic genes was compared between equine hydrallantois and age-matched, normal placentas. Results: In the hydrallantoic samples, edema was the main pathological finding. The capillary density was significantly lower in the hydrallantoic samples than in normal placentas. The reduction in the number of vessels was associated with abnormal expression of a subset of angiogenic and hypoxia-associated genes including VEGF, VEGFR1, VEGFR2, ANGPT1, eNOS and HIF1A. We believe that the capillary density and the abnormal expression of angiogenic genes leads to tissue hypoxia (high expression of HIF1A) and edema. Finally, we identified a lower expression of genes associated with steroidogenic enzyme (CYP19A1) and estrogen receptor signaling (ESR2) in the hydrallantoic placenta. Discussion: Based on the presented data, we believe that formation of edema is due to disrupted vascular development (low number of capillaries) and hypoxia in the hydrallantoic placenta. The edema leads to further hypoxia and consequently, causes an increase in vessel permeability which leads to a gradual increase in interstitial fluid accumulation, resulting in an insufficient transplacental exchange rate and accumulation of fluid in the allantoic cavity.

Original languageEnglish
Pages (from-to)101-112
Number of pages12
StatePublished - Apr 2020

Bibliographical note

Funding Information:
This work was funded by the Special Research Fund (BOF) at Ghent University, the Albert G. Clay Endowment and the Paul Mellon Postdoctoral fellowships at the University of Kentucky.

Publisher Copyright:
© 2020


  • Angiogenesis
  • Equine
  • Fetal placenta
  • Hydrallantois
  • Hydrops

ASJC Scopus subject areas

  • Reproductive Medicine
  • Obstetrics and Gynecology
  • Developmental Biology


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