PREPARATION DETAILS:

Organ: Lactating breast tissues
Origin: Human
Staining: Azan

METHOD AND SPECIMEN DESCRIPTION:

Histological section of a human lactating mammary gland. The Azan stain clearly differentiates connective tissue (blue) from epithelial and secretory components, allowing easy comparison with the non-lactating breast.

OBJECTIVE OF THE EXAMINATION:

To examine the structure of the lactating mammary gland and compare it with that of the non-lactating breast.

SPECIAL FEATURES OF THE PREPARATION:

The lactating breast shows a marked increase in glandular tissue, consisting of numerous secretory alveoli (acini) lined by cuboidal to columnar glandular epithelial cells.

• Milk production occurs within these epithelial cells and is released into the alveolar lumen by two mechanisms:

  • Apocrine secretion, in which part of the cell membrane and cytoplasm are released with the milk fat.

  • Merocrine secretion, in which milk proteins are secreted by exocytosis.

• The terminal ducts collect the secretions and convey them to the lactiferous ducts.

• Myoepithelial cells are present beneath the glandular epithelium and along the ducts; their contraction assists in the ejection of milk.

• The glandular parenchyma is organized into lobules separated by connective tissue septa, with adipose tissue interspersed between lobules.

• Compared to the non-lactating breast, there is a greatly reduced proportion of connective tissue and a corresponding expansion of glandular elements.

TASKS:

• Identify the glandular tissue and the intervening connective tissue.

• Observe the lobular organization of the mammary gland.

• Identify the alveolar epithelial cells, myoepithelial cells, and terminal ducts.

• Compare the amount of glandular and stromal tissue with that of the non-lactating breast.

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