New Insights of Mammary Gland During Different Stages of Development

Abstract

Mammary gland is a unique organ with its function of milk synthesis, secretion, and involution to prepare the gland for subsequent lactation. The mammary epithelial cells proliferate, differentiate, undergo apoptosis, and tissue remodeling following a cyclic pathway in lactation -involutionlactation cycle, thus fine tuning the molecular events through hormones, and regulatory molecules. Several studies are performed on the mammary gland development, lactogenesis, and involution process in molecular details. The developmental stages of mammary gland are embryonic, prepubertal, pubertal, pregnancy, lactation, and involution. Major developmental processes occur after puberty with hormones and growth factors playing crucial role. The two major pathways such as Janus kinases-signal transducer and activator of transcription pathway and PI3K-Akt pathway play a major role in maintaining the lactation. The involution process is a well-orchestrated event involving several signaling molecules and making the gland ready for subsequent lactation. The review focuses on findings with molecular details of different stages of the mammary gland development and signaling pathways involved in lactation-involution cycle. Deep insight into the developmental stages of mammary gland will pave the way to understand mammary gland biology, apoptosis, oncogenesis, and it will help the researchers to use mammary gland as a model for research on various aspects.

Genomewide Association Analyses of Lactation Persistency and Milk Production Traits in Holstein Cattle Based on Imputed Whole-Genome Sequence Data

“…The other genes identified on BTA14 (SHARPIN, CYC1, EXOSC4, PARP10, OPLAH, GRINA, and PLEC) were recently strongly associated with milk production traits, including PROT [37,93,102]. According to Jena et al [103], SHARPIN influences mammary gland development and controls extracellular matrix organization of stroma during branching morphogenesis, which induces alveologenesis during pregnancy and lactation. Moreover, Lin et al [104] found strong association of SHARPIN, CYC1, EXOSC4, and PARP10 with milk serum albumin, which is one of the main protein contents of cattle milk.…”

Anatomy and Physiology of Water Buffalo Mammary Glands: An Anatomofunctional Comparison with Dairy Cattle

“…It should be noted that this invagination process is not dependent on hormonal action [65]. At the onset of puberty, ovarian steroid hormones accelerate the extension and branching of the mammary ducts [66]. During pregnancy, ductal branching continues.…”

Influence of Fibroblasts on Mammary Gland Development, Breast Cancer Microenvironment Remodeling, and Cancer Cell Dissemination

“…By and large, the mammary gland develops mainly postnatally in puberty, pregnancy, lactation, and involution—stages in which reproductive hormones and growth factors play a decisive role [ 3 , 4 , 5 ]. At the onset of puberty, the ovarian steroid hormones regulate branching morphogenesis by promoting the extension and branching of mammary ducts ( Figure 1 C) [ 5 ]. Then, at a later stage, the epithelium infiltrates the fat-pad stroma and builds the mammary gland.…”

“…It has a complex structure comprising a branching epithelium surrounded by a stromal microenvironment [ 1 ]. The interaction between these two compartments, together with a series of growth hormones and growth factors, modulates its development [ 2 , 3 , 4 , 5 ]. Notably, in breast cancer (BC), alterations in the signaling pathways regulating the development of the physiological mammary gland contribute to cancer growth [ 6 , 7 , 8 , 9 ].…”