Maternal and neonatal physiology
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
Lactation is the synthesis and secretion of milk by mammary glands. Progesterone stimulates the development of alveoli, which are spherical collections of cells that produce milk. Under the influence of placental hormones (progesterone and oestrogens), the alveoli mature and the breast is able to secrete milk. During pregnancy, oestrogens and progesterone inhibit the lactogenic action of prolactin, but this inhibitory action is lost after delivery and lactation commences. Colostrum is secreted in the first few days after delivery. Colostrum is rich in proteins, minerals and immunoglobulins but low in fats and sugar. The composition of milk gradually changes, and by 3 weeks post-partum mature milk that is rich in fats, proteins and sugars is produced. Lactose is the chief milk sugar, whereas casein, lactoglobulin and α-lactalbumin are the chief milk proteins.
Reproductive System and Mammary Gland
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
In the male, development of the mammary gland remains relatively rudimentary in comparison with the female. In rodents, testosterone from the developing testis induces mesenchymal cells expressing the androgen receptor to destroy the growing mammary stalk (Dürnberger and Krotochwil 1980). As a consequence, many strains of male mice lack nipples and the duct system largely regresses, while in rats the mammary duct system remains intact, but lacks communication with the exterior (Sakakura 1987). In the male rat, dog, and NHP, growth of the mammary duct system during the juvenile period is limited as in females. In the NHP, transient gynecomastia has been reported in young pubertal males, but it is unclear if this is similar to that reported in young boys (Cline and Wood 2008). In the rat, there are significant androgen-driven changes at puberty, while in the dog and NHP, there is relatively little growth after puberty (Ahrén and Etienne 1957; Cline and Wood 2008; Turner and Gomez 1934). Despite its lack of development in the male dog and NHP, the mammary gland remains responsive to exogenous hormones (Biegel et al. 1998; Daane and Lyons 1954) and can be a useful marker of estrogenic endocrine disruption (Latendresse et al. 2009).
Breast
Joseph Kovi, Hung Dinh Duong in Frozen Section In Surgical Pathology: An Atlas, 2019
The mammary glands are considered to be modified sweat glands and develop from an ingrowth of the ectoderm that gives rise to the ducts and alveoli.41 The epithelial parenchyma consists of 15 to 25 irregular lobes, each emptying into a separate lactiferous duct which terminates in the nipple. The lobes are subdivided into a large number of lobules. The lobule is the essential structural unit of the female mammary gland and is made up of elongated tubules, the alveolar ducts, which are covered by small saccular buds, the alveoli.42 In males the mammary gland undergoes regression after birth, and lobules do not develop. The alveoli and the alveolar duct in the lobule of the resting mammary gland are lined by a single layer of cuboidal epithelial cells resting on a distinct basal lamina (basement membrane). Occasionally, clear myoepithelial cells are interposed between the basal lamina and the epithelial cells (Figure 24).
Silver nanoparticles compromise the development of mouse pubertal mammary glands through disrupting internal estrogen signaling
Published in Nanotoxicology, 2020
Zhe Wang, Qingqing Li, Lining Xu, Juan Ma, Bing Wei, Zhen An, Weidong Wu, Sijin Liu
Nanomaterial administration may exert adverse effects on reproductive system and disrupt normal sex hormone levels (Iavicoli et al. 2013; Lu et al. 2013). For example, gold nanoparticles were demonstrated to largely increase estradiol output in ovarian granulosa cells after 1–5 h treatment, whereas greatly decrease estradiol following 24 h exposure (Stelzer and Hutz 2009). The mammary gland is an estrogen-responsive organ (Brisken and O’Malley 2010). These preliminary findings inspired us to speculate that AgNPs might compromise the development of mammary glands by regulating estrogenic hormonal levels. The diminished ERα expression also indicated that AgNPs disturbed estrogen production. In fact, the serum levels of 17β-estradiol (E2), the principal estrogen, were reduced in a dose- and size-dependent pattern in mice treated with AgNP-20 or AgNP-50, especially in mice exposed to AgNP-20 at 100 μg/kg body weight, compared to the control mice (Figure 8, p< 0.05). This is in line with a previous study that AgNPs significantly decreased E2 levels in rats (Mirzaei, Razi, and Sadrkhanlou 2017). No significant reduction of serum E2 levels was observed in AgNO3-treated mice (Figure 8). These results suggested that the accumulation of AgNPs in the body consequently inhibited estradiol synthesis.
Cross talk of vascular endothelial growth factor and neurotrophins in mammary gland development
Published in Growth Factors, 2020
Kamini Dangat, Amrita Khaire, Sadhana Joshi
Breast milk is the only source of nutrients and bioactive components for the infant during the early postnatal period (Gila-Diaz et al. 2019; Maru et al. 2013). Breast milk composition plays an important role in determining the baby's growth, development and cognition. The mammary gland is one of the few organs that undergoes cycles of growth, differentiation, functional activity, and involution during the postnatal life (Pepper et al. 2000). Mammary glands undergo major changes during lactation to prepare for milk production (Andres and Djonov 2010; Bao et al. 2016). During this period, mammary epithelial cells multiply to produce the lobuloalveolar structures (Islam et al. 2010). The lobuloalveolar growth and differentiation is mediated by angiogenesis to increase blood supply to the mammary gland. This further leads to expansion of the alveoli which are composed of basket-like endothelial “honey combs”. During the second half of pregnancy, alveolar morphogenesis occurs, which is then followed by the structural and functional differentiation of alveolar epithelial cells. These changes are essential for milk fat and protein secretion during the period of lactation (Pepper et al. 2000). Angiogenesis is essential for alveolar development and function, particularly for milk production (Matsumoto et al. 1992; Pepper et al. 2000; Djonov et al. 2001). During pregnancy, the mammary epithelium along with its vasculature undergoes significant growth and proliferation for increased milk production; however the mechanisms coordinating this vascular development are unclear (VanKlompenberg et al. 2016).
Thymoquinone ameliorates obesity-induced metabolic dysfunction, improves reproductive efficiency exhibiting a dose-organ relationship
Published in Systems Biology in Reproductive Medicine, 2019
Seba Harphoush, Guoqing Wu, Gao Qiuli, Margaret Zaitoun, Maissam Ghanem, Yonghui Shi, Guowei Le
Milk synthesis and secretion are the main functions of the mammary gland. At the onset of pregnancy, proliferation, and differentiation of the epithelium begin to form grape-shaped milk secretion system called alveoli. The density of the epithelial area increases compared to the adipose area revealing alveolar lumens structures and expanded ducts within the parenchymal tissue. After parturition and during lactation, the alveolar luminal area expands, milk is produced by luminal secretory cells, and stored within the lumen of alveoli (Richert et al. 2000; Anderson et al. 2007). The architecture of the mammary gland epithelium can be easily observed using whole mount at all stages of the development (Plante et al. 2011a), while measuring the alveolar lumens area is a clear evidence of lactation establishing and evolution (Anderson et al. 2007). These two tests can give important insights into mammary gland development and function.
Related Knowledge Centers
- Breast
- Exocrine Gland
- Galactorrhea
- Lactation
- Milk
- Offspring
- Udder
- Gestation
- Sex Hormone
- Male Lactation