A Guide to Breast Cancer Research From Cellular Heterogeneity and Molecular Mechanisms to Therapy.pdf
Understanding the normal mammary gland, its many cell types, their complex interactions, and the governing cellular pathways provides a fundament for understanding breast carcinogenesis.
In Chap.2,Marja Mikkola and her colleagues at the University of Helsinki,Finland, explore the intricate process of embryonic mammary gland development. It begins with bilateral mammary line formation, progresses throughstages like placode, bud, and sprout, and culminates in branching morpho-genesis. Interaction between primary and secondary mammary mesenchyme drives this process, with cell influx dominating early growth and increased cell proliferation during the sprout stage. Signaling pathways like Wnt/B–catenin, Fgf, and Eda play key roles, hinting at a connection to ancestral hairfollicles.Unique features include Pthlh signaling and inhibition of Hedgehog activity, alongside mechanisms like EMT and MET, crucial for development and remodeling.
Embryonic mammary gland development unfolds with the specification of bilateral mammary lines, thereafter progressing through placode,bud,and sprout stages before branching morphogenesis.
Extensive epithelial-mesenchymal interactions guide morphogenesis from embryogenesis to adulthood. Two distinct mesenchymal tissues are involved,the primary mammary mesenchyme that harbors mammary inductive capacity,and the secondary mesenchyme,the precursor of the adult stroma.Placode and bud stages are morphologically similar with other ectodermal appendages like the hair follicle, reflecting the mammary gland’s assumed evolutionary origin from anancestral hair follicle-associated glandularunit.