title: Structure and functions of the placenta in common minke (Balaenoptera acutorostrata), Bryde's (B. brydei) and sei (B. borealis) whales.
abstract: The structure and functions of placentas were examined in 3 species of rorqual whales, common minke (Balaenoptera acutorostrata), Bryde's (B. brydei) and sei (B. borealis) whales, with the aim of confirming the structural characteristics of the chorion, including the presence of the areolar part, and clarifying steroidogenic activities and fetomaternal interactions in the placentas of these whales. Placentas were collected from the second phase of the Japanese Whale Research Program under Special Permit in the North Pacific (JARPN II). Histological and ultrastructural examinations revealed that these whale placentas were epitheliochorial placentas with the interdigitation of chorionic villi lined by monolayer uninucleate cells (trophoblast cells) and endometrial crypts as well as folded placentation by fold-like chorionic villi. Moreover, well-developed pouch-like areolae were observed in the placentas, and active absorption was suggested in the chorionic epithelial cells of the areolar part (areolar trophoblast cells). Berlin blue staining showed the presence of ferric ions (Fe(3+)) in the uterine glandular epithelial cells and within the stroma of chorionic villi in the areolar part. An immunohistochemical examination revealed tartrate-resistant acid phosphatase (TRAP; known as uteroferrin in uteri) in the cytoplasm of glandular cells and areolar trophoblast cells. This result suggested that, in cetaceans, uteroferrin is used to supply iron to the fetus. Furthermore, immunoreactivity for P450scc and P450arom was detected in trophoblast cells, but not in areolar trophoblast cells, suggesting that trophoblast cells synthesize estrogen in whale placentas. Therefore, we herein immunohistochemically revealed the localization of aromatase and uteroferrin in cetacean placentas during pregnancy for the first time.
authors.affiliation: Laboratory of Veterinary Anatomy, Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan.
authors.forename: Chiyo
authors.initials: C
authors.lastname: Kitayama
authors.forename: Motoki
authors.initials: M
authors.lastname: Sasaki
authors.forename: Hajime
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Mogoe
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohsumi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Fukui
authors.forename: Teguh
authors.initials: T
authors.lastname: Budipitojo
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kondoh
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kitamura
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D050616:Balaenoptera / Q000502:physiology*; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism*; D002823:Chorion / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D003593:Cytoplasm / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D004717:Endometrium / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D007120:Immunochemistry; D007501:Iron / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism*; D007564:Japan; D008855:Microscopy, Electron, Scanning; D050636:Minke Whale / Q000502:physiology*; D010140:Pacific Ocean; D010920:Placenta / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D010929:Placentation; D011247:Pregnancy; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D000071681:Tartrate-Resistant Acid Phosphatase; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D007527:Isoenzymes; D007501:Iron; D001141:Aromatase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase