title: Alterations in mast cell frequency and relationship to angiogenesis in the rat mammary gland during windows of physiologic tissue remodeling.
abstract: BACKGROUND
  The mammary epithelium undergoes proliferation and regression accompanied by remodeling of the fibrocellular and vascular stroma. Mast cells are abundant in these compartments and have been implicated in remodeling during wound healing and cancer progression. The purpose of this study was to test the hypothesis that mast cell abundance correlates with physiologic mammary tissue remodeling during estrous cycling, lactogenesis (pregnancy and lactation) and involution.
  
  
  RESULTS
  Mast cell and capillary frequency were quantified in the stroma surrounding ducts and lobules from mammary glands of rats. During estrous cycling, periductal mast cell numbers were unchanged, but lobule-associated mast cells significantly increased in the regressive phase of diestrus II. During lactogenesis, lobular stroma mast cells peaked early in pregnancy, at D2, followed by a significant decrease throughout lactation. Involution was associated with a rapid return in mast cell numbers, similar to diestrus II. Lobular vascularization peaked during the state of metestrus, when limited secretory differentiation occurs. Lobular angiogenesis peaked at D7 of pregnancy, regressed, and then returned to high levels during lactation and early involution, when secretory differentiation is high.
  
  
  CONCLUSIONS
  These results suggest mast cells are predominantly associated with regressive lobular remodeling during cycling and involution, whereas angiogenesis is predominantly associated with secretory differentiation.
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Ramirez
authors.forename: Amy
authors.initials: A
authors.lastname: Lee
authors.forename: Pepper
authors.initials: P
authors.lastname: Schedin
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Russell
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Masso-Welch
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000502:physiology*; D008407:Mast Cells / Q000166:cytology / Q000502:physiology*; D018919:Neovascularization, Physiologic / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley