Analyzing Cell-ECM Interactions in Adult Mammary Gland by Transplantation of Embryonic Mammary Tissue from Knockout Mice - Methods in Molecular Biology: Extracellular Matrix Protocols - page 327

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Analyzing Cell-ECM Interactions
in Adult Mammary Gland by Transplantation
of Embryonic Mammary Tissue from Knockout Mice
Teresa C. M. Klinowska and Charles H. Streuli
1. Introduction
1.1. Background
Understanding the function of ECM and cell-matrix interactions in mam-
malian development has reached new levels of sophistication with the intro-
duction of gene knockout technology. Indeed, two of the chapters in this
volume provide detailed methods for producing mice with deletions in specific
ECM genes ( see Chapters 13 and 14). However, in some knockout mice, ani-
mals die during late embryogenesis or shortly after birth. In such cases, it is
possible to analyze embryonic developmental phenotypes, but it is less easy to
determine the in vivo role of cell-matrix interactions in adult tissues.
Although this problem has been partially solved by the development of tis-
sue-specific knockouts ( see Chapter 13), the approach relies on appropriate
tissue-specific promoters. In many cases, genes that uniquely characterize spe-
cific cell types within complex tissues have not been identified. Thus, knock-
out technology can be restrictive when analyzing cell-matrix interactions in
specific cases of tissue development and/or homeostasis.
A significant proportion of mammary gland development occurs postnatally.
Epithelial cells within this tissue are organized as two-layered ductal structures
consisting of a central layer of luminal epithelial cells and a basal layer of
myoepithelial cells contacting basement membrane. These ductal networks are
embedded within mammary stroma. The formation of ducts and development
of lactational alveoli are highly dynamic events that occur during various
developmental stages of the mammary gland. The mechanism of tissue mor-