Article

Murine progesterone receptor expression in proliferating mammary epithelial cells during normal pubertal development and adult estrous cycle. Association with eralpha and erbeta status.

Urological Research Centre and Clinic, Department of Surgery, University of Western Australia, Queen Elizabeth II Medical Centre, Nedlands, WA, Australia.
Journal of Histochemistry and Cytochemistry (impact factor: 2.72). 11/1999; 47(10):1323-30. pp.1323-30
Source: PubMed

ABSTRACT The ovarian steroids estrogen and progesterone are important in directing the normal growth and development of the mouse mammary gland. Previously, we have demonstrated that the majority of proliferating mammary epithelial cells do not express estrogen receptor-alpha (ERalpha). In this study we examined the relationship between progesterone receptor (PR) expression and proliferation in mammary epithelial cells using simultaneous immunohistochemistry for progesterone receptor (PR) and tritiated thymidine [(3)H]-Tdr) autoradiography. Results showed that the majority (>80%) of mammary epithelial cells labeled with [(3)H]-Tdr were PR-positive in the terminal end buds (TEBs) of pubertal mice and the ducts of pubertal and adult mice. Whereas the majority of mammary epithelial cells were also PR-positive, the basal cell population, which comprises the minority of mammary epithelial cells in the mammary ducts, was predominantly PR-negative. Nevertheless, the PR-positive phenotype remained the major proliferating cell type in the basal population. These findings suggest that the progesterone signaling pathway is involved in the proliferation of basal cell populations, potentially directing formation of tertiary side branching during pubertal development and alveolar bud formation in adult glands. A proportion of the basal cells exhibited weak expression of ERbeta, suggesting that the role of ERbeta in mediating normal estrogen-induced responses should be further studied. (J Histochem Cytochem: 47:1323-1330, 1999)

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Keywords

adult glands
 
alveolar bud formation
 
basal cell population
 
basal cell populations
 
basal cells exhibited weak expression
 
estrogen receptor-alpha
 
J Histochem Cytochem
 
major proliferating cell type
 
mammary epithelial cells
 
mediating normal estrogen-induced responses
 
mouse mammary gland
 
PR-positive phenotype
 
progesterone
 
progesterone receptor
 
progesterone signaling pathway
 
proliferating mammary epithelial cells
 
pubertal development
 
simultaneous immunohistochemistry
 
terminal end buds
 
tertiary side branching