Abstract: Under transmission electron microscope, the prehypophyseal cells in F1 hybrid-marrah buffalo have five marked cells types in common, their ultrastructural features appeared characteristically. Gonadotrophs are round in shape, which about 7.6 to 9.0 μm in diameter; the size of secretory granules is either big or small clearly, which has high electron density. Thyrotroph is about 6.0 to 7.5 μm in diameter and contains irregular nuclei in the centre mostly; their secretory granules are generally minor and tiny，distributed in the vicinity of plasmalemma. Adrenocorticotrophic hormone(ACTH)cells are ovoid in shape and 7.1 to 8.5 μm in diameter; irregular nuclei always is side incline; their secretory granules occurred in cytoplasmic periphery or one side. Somatotrophs are round, containing rounded nuclei and numerous secretory granules. Lactotrophs are almost the biggest cells in pituitary, numerous cells of various size are full of periplast. The results aimed to provide the morphology basic data for controlling reproduction endocrine in F1 hybrid-marrah buffalo.

Key words: prehypophyseal cells; ultrastructure; F1 hybrid-marrah buffalo