title: Erythropoietin and erythropoietin-receptor producing cells demonstrated by in situ hybridization in mouse visceral yolk sacs.
abstract: We have previously demonstrated that mRNAs for erythropoietin and the erythropoietin receptor temporarily express on the visceral yolk sacs on days 9-11 of gestation in mice. In order to investigate the sites of expression, we performed in situ hybridization on visceral yolk sacs. Visceral yolk sacs from 10-day-old mice embryos were frozen in liquid nitrogen, and processed for cryosections. Sections were hybridized with a 35S-labeled RNA probe complementary to mRNA coding for erythropoietin or erythropoietin receptor. Erythropoietin mRNA was detectable in 57.6% of the endodermal epithelial cells, while erythropoietin-receptor mRNA was discerned in 90.8% of the endodermal cells and mesodermal cells, including hemocyteblasts. Moreover, erythropoietin protein was detectable in 52.8% of the endodermal epithelial cells, and on the surface of hemocyteblasts and mesothelial cells. Erythropoietin-receptor protein was discernible in 87.2% of the endodermal cells and in the corresponding mesodermal cells to those where erythropoietin protein was expressed by immunohistochemical examinations. The results indicate that erythropoietin-synthesizing cells are located in half of the endodermal epithelial cells, while the majority of cells in the visceral yolk sac are erythropoietin-receptor-producing cells, indicating that almost all cell population in the visceral yolk sac is erythropoietin-responding cells via both autocrine and paracrine routes.
authors.affiliation: Department of Anatomy, Division 1, Kinki University School of Medicine, Osaka-Sayama, Osaka 589-8511, Japan. y1126yas@med.kindai.ac.jp
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Yasuda
authors.forename: Masaki
authors.initials: M
authors.lastname: Okano
authors.forename: Masaya
authors.initials: M
authors.lastname: Nagao
authors.forename: Seiji
authors.initials: S
authors.lastname: Masuda
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Fujita
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Sasaki
mesh_terms: D000818:Animals; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism*; D005260:Female; D017403:In Situ Hybridization; D051379:Mice; D008813:Mice, Inbred ICR; D011247:Pregnancy; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000378:metabolism*; D015017:Yolk Sac / Q000166:cytology / Q000378:metabolism*
chemical_list: D017467:Receptors, Erythropoietin; D004921:Erythropoietin