Journal of Reproductive Immunology 42 (1999) 135–145 Localization of granulocyte-macrophage colony-stimulating factor in the bovine reproductive tract A.A.S. de Moraes 1 , F.F. Paula-Lopes, N. Chegini, P.J. Hansen * Department of Dairy and Poultry Sciences and Department of Obstetrics and Gynecology, Uniersity of Florida, Gainesille, Florida 32611 -0920, USA Accepted 8 July 1998 Abstract Granulocyte-macrophage colony-stimulating factor (GM-CSF) can increase embryo devel- opment to the blastocyst stage in cattle. The objective of the present study was to determine whether GM-CSF is present in the reproductive tract. Using Western blotting, immunoreac- tive GM-CSF was detected in uterine flushings from cows at days 0, 7, and 14 of the estrous cycle and from cows at days 14–17 of pregnancy. Also, GM-CSF was localized immunohis- tochemically to endometrium and oviduct. Patterns of immunohistochemical localization and intensity of reaction product were similar for all days of the estrous cycle. While present in several cell types, immunoreactive product in the endometrium was greatest in epithelium (especially luminal epithelium). Immunoreactive GM-CSF was also localized to epithelium in ampullary and isthmic regions of the oviduct, with intensity greater in ampulla. Staining was observed for both ciliated and non-ciliated cells. In conclusion, the bovine oviduct and endometrium contain immunoreactive GM-CSF and this molecule is present in uterine secretions. Thus, this cytokine is a potentially important intracellular regulator of endome- trial, oviductal and embryonic function during early pregnancy in the cow. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Granulocyte-macrophage colony-stimulating factor; Bovine; Reproductive tract * Corresponding author. 1 Present address: Faculdade de Medicina Veterina ´ria, Universidade Federal do Rio Grande do Sul, caixa postal 15094, CEP: 91-501970, Porto Alegre, RS, Brazil. 0165-0378/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII:S0165-0378(98)00075-8