Immunohistochemical localization of SPHK1 in sections of nongravid and gravid uteri collected from unilaterally pregnant ewes on Days 20, 40, 80, and 120 of gestation (A) and Day 80 of gestation (B). Rabbit IgG applied to a Day 80 placentome served as a negative control. GE, uterine glandular epithelium; Tr, placental trophectoderm/chorion; BV, blood vessels; Myo, myometrium; CAR, caruncular tissue; COT, cotyledonary tissue; scST, endometrial stratum compactum stroma; Syn, epithelial syncytia of the placentome. Arrowheads indicate placental trophectoderm in (B). Representative images are shown from independent samples (n = 4). Width of each field is 940 μm (A) and 220 μm (B).