Electron micrograph (EM) of a somatotroph in the anterior lobe. These ultrastructural features are typical of those of a protein-secreting endocrine cell. Many organelles such as a well-developed Golgi complex needed for hormone synthesis and clustered round to ovoid secretory vesicles (arrows) with a moderately dense core are close to the cell membrane. The oval euchromatic nucleus has a prominent nucleolus (nu). The cell abuts a fenestrated capillary (Cap), which contains an erythrocyte. 12,000×.