The Role of Myoepithelium in Mammary Development and Tumorigenesis

SUMMARY Treatment of pregnant rats with an anti-androgen (1,2α-methylene-6-chloro-Δ4,6-pregnadiene-17α-ol-3,20-dione-17α-acetate, 'cyproterone acetate') from the 13th day of pregnancy resulted in female organogenesis of the mammary glands, including the formation of nipples in the male foetuses and feminization of other male sexual characters. The continued development of the nipple primordium was also seen in all the subsequent foetal and postnatal stages even after termination of the treatment. A more marked development of the foetal mammary tissue as compared with that of male controls was noted in the proximal areas of the mammary cord process between the 19th and the 21st day in male foetuses whose mothers had received the anti-androgen. In male foetuses of treated mothers, a further proliferation of the glandular tissue was also found after birth. The role of androgens in the development of the mammary glands is discussed. It seems likely from our findings that the androgens of a male foetus inhibit the development of the mammary glands, emphasizing that for mammary development before puberty female gonadal hormones are not necessary.

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Nutritional Regulation of Mammary Gland Development and Milk Synthesis in Animal Models and Dairy Species

Genes ◽

10.3390/genes12040523 ◽

2021 ◽

Vol 12 (4) ◽

pp. 523

Author(s):

Cathy Hue-Beauvais ◽

Yannick Faulconnier ◽

Madia Charlier ◽

Christine Leroux

Keyword(s):

Gene Expression ◽

Molecular Mechanisms ◽

Mammary Gland Development ◽

Mammary Development ◽

Feed Restriction ◽

Nutritional Regulation ◽

Milk Component ◽

Lipid Supplementation ◽

Gland Development

In mammals, milk is essential for the growth, development, and health. Milk quantity and quality are dependent on mammary development, strongly influenced by nutrition. This review provides an overview of the data on nutritional regulations of mammary development and gene expression involved in milk component synthesis. Mammary development is described related to rodents, rabbits, and pigs, common models in mammary biology. Molecular mechanisms of the nutritional regulation of milk synthesis are reported in ruminants regarding the importance of ruminant milk in human health. The effects of dietary quantitative and qualitative alterations are described considering the dietary composition and in regard to the periods of nutritional susceptibly. During lactation, the effects of lipid supplementation and feed restriction or deprivation are discussed regarding gene expression involved in milk biosynthesis, in ruminants. Moreover, nutrigenomic studies underline the role of the mammary structure and the potential influence of microRNAs. Knowledge from three lactating and three dairy livestock species contribute to understanding the variety of phenotypes reported in this review and highlight (1) the importance of critical physiological stages, such as puberty gestation and early lactation and (2) the relative importance of the various nutrients besides the total energetic value and their interaction.

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