title: Macrophages promote collagen fibrillogenesis around terminal end buds of the developing mammary gland.
abstract: Development of the ductal network in the mammary gland is dependent in part on the presence of macrophages. Here we utilize multi-photon microscopy and second harmonic generation to describe terminal end bud 3-dimensional structure and the organization of the surrounding collagen matrix. We have applied this approach to analyze the effect of macrophage deficiency on terminal end bud structure and collagen organization, using mice homozygous for a null mutation in the colony stimulating factor-1 gene (Csf1op/Csf1op). Primary terminal end buds have an oblong shape, with long collagen I fibers close to the neck of the terminal end bud and radiating upwards in the direction of growth. Around the terminal end buds, the amount of total collagen I detected by antibody staining was not affected by macrophage deficiency. However the amount of collagen I organized into long fibers, detected by second harmonic generation signal, was reduced in Csf1op/Csf1op mice. Macrophage deficiency also caused terminal end buds to be rounder and shorter. These studies reveal a role for macrophages in collagen fibrillogenesis and in organization of the structure of terminal end buds.
authors.affiliation: Department of Molecular and Developmental Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: Wendy V
authors.initials: WV
authors.lastname: Ingman
authors.forename: Jeff
authors.initials: J
authors.lastname: Wyckoff
authors.forename: Valerie
authors.initials: V
authors.lastname: Gouon-Evans
authors.forename: John
authors.initials: J
authors.lastname: Condeelis
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Pollard
mesh_terms: D000818:Animals; D002465:Cell Movement; D024042:Collagen Type I / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D016173:Macrophage Colony-Stimulating Factor / Q000172:deficiency / Q000235:genetics; D008264:Macrophages / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D036641:Microscopy, Fluorescence, Multiphoton
chemical_list: D024042:Collagen Type I; D016173:Macrophage Colony-Stimulating Factor