Immunohistological study of LH-immunoreactive cells in the porcine anterior pituitary

Anterior pituitary glands were removed from 18 sows at different stages of their estrous cycle to immunohistologically study the relationship between the stage of the estrous cycle and state of the luteinizing hormone (LH)-immunoreactive cells. The LH-immunoreactive cells were grouped into three types according to the amount of LH-immunoreactive granules stored in the cytoplasm (types A, B, and C). The number of LH-immunoreactive cells fluctuated along with the stage of the estrous cycle. In the 1st and the 6th stages, numerous LH-immunoreactive cells were observed (398±39, 391±60 cells/10-2mm2, respectively). In the 2nd stage, only a few cells were observed (6 cells/10-2mm2) and from the 3rd to the 5th stages, their number gradually increased.