This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Budik, S. Articles by Aurich, C. Search for Related Content PubMed PubMed Citation Articles by Budik, S. Articles by Aurich, C.

Significance of aquaporins and sodium potassium ATPase subunits for expansion of the early equine conceptus

¹ Department for Animal Breeding and Reproduction, Centre for Artificial Insemination and Embryo Transfer² Department of Pathobiology, Institute of Histology and Embryology, University of Veterinary Medicine Vienna, Vienna A-1210, Austria³ Department of Biochemistry, University of Vienna, Vienna A-1030, Austria

Correspondence should be addressed to S Budik; Email: sven.budik{at}vu-wien.ac.at

Expansion of the equine conceptus can be divided into blastocoel and yolk sac phases. The endodermal layer transforming the blastocoel into the yolk sac is completed around day 8 of pregnancy. From that time, the size of the spherical conceptus increases tremendously due mainly to the accumulation of fluid rather than cell multiplication. In this study, we have investigated the abundance and localisation of Na⁺/K⁺-ATPases and aquaporins (AQP) in the equine conceptus on days 8, 10, 12, 14 and 16 by multiplex reverse transcriptase PCR, Western blot and immunohistochemistry. During conceptus expansion, the ectoderm of the yolk sac exhibited basolateral abundance of 1ATPase, apical localisation of AQP5, and membrane and cytoplasmic expression of AQP3. With increasing conceptus size its cells showed an extensive enlargement of the apical membrane surface by microvilli. From day 14 onwards, the yolk sac endoderm forms arc-like structures with attaching sites to the ectodermal layer and shows intensive staining for 1ATPase, AQP5 and AQP3 in the membrane as well as in the cytoplasm. In the yolk sac ectoderm, the arrangement of these proteins is comparable with the collecting ducts of kidney with AQP2 being replaced by the closely related AQP5. The detection of phosphorylation sites for protein kinase A suggests a similar AQP5 traffic and regulation as known for AQP2 in the collecting ducts of the kidney. The arrangement of these proteins in equine embryos indicates at least partially the mechanism of conceptus expansion.

This article has been cited by other articles:

				S. Wilsher and W R Allen Uterine influences on embryogenesis and early placentation in the horse revealed by transfer of day 10 embryos to day 3 recipient mares Reproduction, March 1, 2009; 137(3): 583 - 593. [Abstract] [Full Text] [PDF]