Identification of the EGF/EGF-R system in the oviduct and endometrium of pigs in early stages of pregnancy and early conceptus.

In the oviduct and endometrium, higher mRNA amounts encoding for EGF were found on day 6 and 12 in cyclic and on day 6 in pregnant pigs compared to signals on day 1. Reproductive state related changes could also be detected for TGFα mRNA in cyclic and pregnant pig oviduct but not in the endometrium. EGF-R protein concentration was higher (P < 0.05) in oviductal membranes on day 1 of the pregnancy (42.6 ± 16.5 fmol mg -1 protein) compared to day 6 and 12 (21.6 ± 6.0 fmol mg -1 protein and 17.1 ± 3.8 fmol mg 1 protein). In the endometrium EGF-R protein concentrations increased (P < 0.05) on day I (14.7 ± 4.8 fmol mg 1 protein) to day 6 (29.0 ± 6.8 fmol mg 1 protein) and day 12 (27.5 ± 7.0 fmol mg protein) of pregnancy. The mature EGF-R protein (170 kDa) was verified in oviductal and endometrial membranes of all pregnant pigs investigated. A biologically intact EGF-R could be detected in all samples by means of autophosphorylation assay. Weak EGF mRNA signals were found in the expanded and filamentous blastocysts. No TGFα transcripts could be amplified during the embryonic stages. Only low amounts of EGF-R mRNA could be detected in zygotes and in filamentous blastocysts.