title: Association of reticular cells with CD34+/Sca-1+ apoptotic cells in the hemopoietic organ of grasshopper, Euprepocnemis shirakii.
abstract: Hemopoiesis in orthopteran insects occurs in a hemopoietic organ that is located bilaterally along the aorta. This organ is also known as a reticulo-hemopoietic organ because of the rich presence of reticular cells. This study was performed to further elucidate hemopoiesis in the reticulo-hemopoietic organ of an orthopteran, Euprepocnemis shirakii. We focused on the question why reticular cells are so abundant (35% of cells in hemopoietic organ). Interestingly, 21% of these reticular cells surrounded hemocytes with their reticular cytoplasm. The surrounded hemocytes were distinguished by their different size and darkly stained nucleus. These cells were characterized by immunostaining using antibodies against several types of hemocytes: 45% of the surrounded hemocytes were CD34+, and these positive cells were double stained (over 85%) when immunostained by another hemopoietic pluripotent cell marker, Sca-1. Transmission electron microscopic analysis showed that reticular cells surrounded hemocytes containing large nuclei and poorly developed cytoplasmic organelles. This strongly suggests that the reticular cells surround hemopoietic stem cells. Additionally, surrounded hemopoietic progenitor cells are undergoing apoptosis as indicated by the TUNEL assay. The enclosed apoptotic cells are engulfed and then phagocytosed by reticular cells. Our results suggest that reticular cells are related to the differentiation and apoptosis of hemopoietic stem cells.
authors.affiliation: Laboratory of Cell Engineering and 3-D Structure, School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, South Korea.
authors.forename: Jong Yeon
authors.initials: JY
authors.lastname: Lim
authors.forename: Bong Hee
authors.initials: BH
authors.lastname: Lee
authors.forename: Seok Woo
authors.initials: SW
authors.lastname: Kang
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Wago
authors.forename: Sung Sik
authors.initials: SS
authors.lastname: Han
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism*; D000950:Antigens, Ly / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D006110:Grasshoppers / Q000502:physiology* / Q000648:ultrastructure*; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000378:metabolism* / Q000648:ultrastructure; D006434:Hemocytes / Q000378:metabolism / Q000648:ultrastructure*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D000950:Antigens, Ly; D008565:Membrane Proteins