Immunoelectron microscopic demonstration of regulated pathway for calcitonin and constitutive pathway for carcinoembryonic antigen in the same cells of human medullary carcinomas of thyroid glands

R. Yoshiyuki Osamura, Osamu Yasuda, Takeshi Kawakami, Yoshiko Itoh, Kenichi Inada, Kenichi Kakudo

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19 Citations (Scopus)

Abstract

The human medullary carcinomas are well known to secrete calcitonin (CT) as a neuroendocrine peptide and carcinoembryonic antigen (CEA) as a serum protein that is integrated into the cell membrane. This ultrastructural study is designed to elucidate whether CT and CEA are secreted via two different intracellular secretory pathways, a regulated pathway and a constitutive pathway. The immunoelectron microscopic postembedding method, performed on four cases of the human medullary carcinomas of the thyroid using plastic embedding material, disclosed two distinct different localization patterns for CT and CEA. CT was localized exclusively in dense cored secretory granules. CEA was present in the cell membrane and in the secretory vesicles. The secretory granules were completely negative for CEA. The trans-Golgi networks were also positive for CT and CEA. Electron microscopic double staining confirmed these localization in the same carcinoma cells. These observations suggest the presence of two distinct pathways in the endocrine cancer cells, i.e., the regulated pathway for CT and the constitutive pathway for CEA.

Original languageEnglish
Pages (from-to)7-11
Number of pages5
JournalModern Pathology
Volume10
Issue number1
Publication statusPublished - 01-01-1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pathology and Forensic Medicine

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