Mammary alveolus

Diagram of breast anatomy showing the mammary alveolus

The mammary alveolus is a small cavity or sac found in the mammary glands of mammals. It is the site of milk production and secretion, playing a crucial role in the process of lactation. Each alveolus is lined with a single layer of epithelial cells that are responsible for the synthesis and secretion of milk.

Structure

The mammary alveolus is a spherical structure composed of secretory epithelial cells. These cells are surrounded by a network of myoepithelial cells and a basement membrane. The myoepithelial cells contract in response to the hormone oxytocin, facilitating the ejection of milk into the ductal system.

The alveoli are organized into clusters known as lobules, which are connected to the lactiferous ducts. These ducts transport milk from the alveoli to the nipple, where it can be accessed by the nursing infant.

Function

The primary function of the mammary alveolus is the production and secretion of milk. This process is regulated by a complex interplay of hormones, including prolactin, estrogen, and progesterone. During pregnancy, these hormones stimulate the growth and development of the alveoli, preparing the mammary glands for lactation.

After childbirth, the hormone prolactin promotes milk synthesis, while oxytocin triggers the milk ejection reflex, also known as the "let-down" reflex. This reflex is essential for the delivery of milk to the infant during breastfeeding.

Development

The development of the mammary alveolus begins during puberty, when increased levels of estrogen stimulate the growth of the mammary glands. During pregnancy, further hormonal changes lead to the proliferation and differentiation of alveolar cells, resulting in the formation of fully functional alveoli capable of producing milk.

Clinical Significance

Understanding the structure and function of the mammary alveolus is important in the context of breastfeeding and breast health. Conditions such as mastitis, galactorrhea, and breast cancer can affect the alveoli and impact milk production and secretion.

Related Pages

• Mammary gland
• Lactation
• Breast anatomy
• Breastfeeding