Cytology of the corpus luteum during pregnancy and sexual cycle in cows

Following ovulation, the granulosa and theca interna cells give rise to a transient endocrine gland known as the corpus luteum (O'Shea et al., 1990). Several investigators (Gemmel, 1995; Weber et al., 1987) have reported the corpus luteum in cows to be composed of two types of luteal cell population; large (granulosa lutein cells) and small (theca lutein cells). The large luteal cells are said to originate from the granulosa cells while the small luteal cells originate from the theca interna (O'Shea et al.; loc. cit) This study was conducted with the aim of determining the cytohistochemical and morphologic properties of the small and large luteal cells during normal cycle as well as in pregnancy.