Immunohistochemical localization of steroidogenic enzymes in corpus luteum of wild sika deer during early mating season

We analyzed the localization of steroidogenic enzymes (P450 sec, 3 ~ HSD, P450 arom and P450 c17) in the corpora lutea of two Hokkaido sika deer (Cer­ uus nippon yesoensis) during the early mating season. Two corpora lutea were found in each female and the timing of formation of the corpora lutea seemed different. P450 sec, and 3 ~ HSD, positive luteal cells were found in both cor­ pora lutea. The existence of two functional corpora lutea from the early mat­ ing season through pregnancy suggests that progesterone secreted by two or more corpora lutea is necessary for maintenance of pregnancy in sika deer.