Reduced quality of bovine embryos cultured in media conditioned by exposure to an inflamed endometrium.
OBJECTIVE
A suboptimal uterine environment contributes to the bovine repeat breeder syndrome. Subclinical endometritis is a component, so the mechanism by which inflammation affects embryo survival was investigated by assessing the effect of non-cellular products of an inflamed endometrium on embryo development to blastocyst.


METHODS
Endometrial fluid from a lactating dairy cow was collected by lavage using embryo culture medium. Aseptic inflammation was then induced by infusion of glycogen and lavage was repeated 6 h later. The recovered fluid was used to culture Day 5 in-vitro-derived embryos for 2 days. Embryo development and quality were compared for two treatment groups (culture media conditioned by inflamed or non-inflamed endometrium) and two controls (control or control + serum).


RESULTS
Development to blastocyst was higher for conditioned media or media + serum (inflamed 42.2%; non-inflamed 49.3%; control + serum 50.9%; control 16.9%; P < 0.001). Blastocyst cell numbers were lower for the conditioned-inflamed group (inflamed, 83.1; non-inflamed, 99.8; control + serum, 100.6; control, 110.1; P < 0.001). Trophectoderm cell number, but not inner cell mass number, was reduced in the conditioned-inflamed group and the inner cell mass:trophectoderm ratio was increased (P < 0.001).


CONCLUSIONS
Altering the embryo culture environment with the products of endometrial inflammation had a subtle effect on embryo quality. An increased inner cell mass:trophoblast ratio is likely to negatively affect embryonic survival. Altered embryo quality is a mechanism for early embryonic failure in cows with subclinical endometritis. Culture of embryos with normal endometrial fluid may improve in vitro embryo production.
Hill
J
J
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, New York 14853-6401, USA. jonathan.hill@uq.edu.au
Gilbert
R
R
D000818:Animals; D001755:Blastocyst / Q000187:drug effects; D002417:Cattle; D002418:Cattle Diseases / Q000503:physiopathology; D003470:Culture Media; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D046149:Embryo Culture Techniques / Q000379:methods / Q000592:standards / Q000662:veterinary*; D004622:Embryo, Mammalian / Q000187:drug effects*; D047108:Embryonic Development / Q000187:drug effects*; D004716:Endometritis / Q000503:physiopathology / Q000662:veterinary*; D004717:Endometrium; D005260:Female; D005307:Fertilization in Vitro; D011247:Pregnancy; D013997:Time Factors
D003470:Culture Media; D017077:Culture Media, Conditioned