妊娠および泌乳期のマウス乳腺における毛細血管の微細構造 Pregnancy and Lactation Affect the Microvasculature of the Mammary Gland in Mice

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妊娠および泌乳期のマウス乳腺における毛細血管の微細構築の変化を血管鋳型で走査電顕により, また微細構造の変化を透過電顕および形態計測を用いて検索した. 血管鋳型の走査電顕観察では, 妊娠に伴って導管周囲の毛細血管叢から盛んに血管が新生され, 分岐と吻合を繰り返しながら, 導管や腺胞を密に取り囲み, 籠状の構築を形成していた. 泌乳期でもこの血管構築は維持され, しかも毛細血管は蛇行していた. 透過電顕観察と形態計測学的検索から, 内皮細胞内の飲小胞の密度は妊娠18日目から泌乳5日目に処女期の約2倍に, さらに泌乳10〜20日目には3倍に増加し, 離乳期に漸減した. 辺縁ヒダや微絨毛様突起の長さは妊娠に伴って漸増し, 泌乳5〜15日目に最大となり, その後漸減した. また, 毛細血管は妊娠末期から泌乳期にかけて壁が薄く, しかも腺胞に極めて接近していた. さらに腺胞の上皮細胞では, 泌乳期に基底陥入がよく発達していた. これらの所見から, 乳腺の毛細血管ほ乳汁産生に必要な物質の輸送に重要な役割を果たしていることが示唆された.

Microvascular changes in the mammary gland in mice during pregnancy and lactation were investigated by scanning electron microscopy (SEM) with a corrosion cast method, transmission electron microscopy (TEM) and morphometry. By SEM, duct-associated capillary plexuses were sparsely distributed to branch into adipocytes during virgin period. With advance in pregnancy, both branches from the capillary plexuses and branches from the vessels surrounding adipocytes extended further to form capillary networks. The basket-like architecture was completed by day 18 of pregnancy. These findings may indicate that angiogenesis occurs frequently during this period. During lactation, the basket-like architecture still remained and the capillaries surrounding alveoli meandered. After weaning, the regression of microvasculature followed the degeneration of alveoli. By TEM and morphometry, the density of binocytotic vesicles (PVs) (number of PVs per μm^2 of endothelium cytoplasm) increased twofold from day 18 of pregnancy to day 5 of lactation, furthermore increased threefold from days 10 to 20 of lactation, and subsequently decreased after weaning. Marginal folds and microvillous processes gradually increased in length with advance in pregnancy, reached the maximum from days 5 to 15 of lactation, and thereafter decreased. In addition, the capillaries with thinner walls were in close contact with alveoli during the late stage of pregnancy and during lactation. Furthermore, the alveolar epithelial cells had well-developed basal infoldings during lactation. These findings suggest that the capillaries play an important role in transporting materials necessary for milk production.

収録刊行物

  • 日本獣医学雑誌

    日本獣医学雑誌 54(5), 937-943, 1992-10-15

    社団法人日本獣医学会

被引用文献:  6件中 1-6件 を表示

各種コード

  • NII論文ID(NAID)
    110003915688
  • NII書誌ID(NCID)
    AA10796138
  • 本文言語コード
    ENG
  • 資料種別
    雑誌論文
  • ISSN
    09167250
  • NDL 記事登録ID
    3800390
  • NDL 刊行物分類
    RB72(畜産--獣医学)
  • NDL 雑誌分類
    ZR22(科学技術--農林水産--畜産)
  • NDL 請求記号
    Z18-350
  • データ提供元
    CJP引用  NDL  NII-ELS 
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