Ovine placenta at high altitudes: Comparison of animals with different times of adaptation to hypoxic environment

Víctor H. Parraguez, Miljenko Atlagich, Rodrigo Díaz, Raquel Cepeda, Carlos González, Mónica De los Reyes, María E. Bruzzone, Claus Behn, Luis A. Raggi

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


Fetal growth and newborn weight from ovine gestations at high altitudes (HA) are greater in ewes that live at HA for several generations than in those native to low altitudes (LA) exposed to HA only during pregnancy. Because the placenta is a key regulator of fetal growth, the present study compared placental characteristics in term pregnancies among ewes native to HA and LA. Conception occurred at HA and ewes continued to reside at HA throughout pregnancy or conception occurred at LA and ewes were transported to HA or remained at LA (controls). Ewes native to LA were moved to HA shortly after mating (group LH) and joined with pregnant ewes native to HA (group HH). After parturition, placental cotyledons were counted and measured for total area and histological estimation of surface occupied by vasculature. The total surface of the cotyledons and surface occupied by vasculature were greater at HA, whereas the number of cotyledons was smaller at HA. These changes were more pronounced in ewes of the HH compared with the LH group. The present study showed that exposure to HA induces, in pregnant ewes, placental morphological changes that may improve maternal-fetal exchange. Moreover, because of accentuation of placental changes in ewes with long-term residence at HA, this appears to be an efficient mechanism of adaptation to hypobaric hypoxia.

Original languageEnglish
Pages (from-to)151-157
Number of pages7
JournalAnimal Reproduction Science
Issue number1-2
Publication statusPublished - Sept 2006


  • High altitude
  • Sheep-placenta

ASJC Scopus subject areas

  • Food Animals
  • Animal Science and Zoology
  • Endocrinology


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