Question 2#

Which of the following changes in the breast is NOT associated with pregnancy

A. Accumulation of lymphocytes, plasma cells, and eosinophils within the breast
B. Enlargement of breast alveoli
C. Release of colostrum
D. Accumulation of secretory products in minor duct lumina

Correct Answer is C


With pregnancy, the breast undergoes proliferative and developmental maturation. As the breast enlarges in response to hormonal stimulation, lymphocytes, plasma cells, and eosinophils accumulate within the connective tissues. The minor ducts branch and alveoli develop. Development of the alveoli is asymmetric, and variations in the degree of development may occur within a single lobule. With parturition, enlargement of the breasts occurs via hypertrophy of alveolar epithelium and accumulation of secretory products in the lumina of the minor ducts. Alveolar epithelium contains abundant endoplasmic reticulum, large mitochondria, Golgi complexes, and dense lysosomes.

Two distinct substances are produced by the alveolar epithelium:

  1. the protein component of milk, which is synthesized in the endoplasmic reticulum (merocrine secretion).
  2. the lipid component of milk (apocrine secretion), which forms as free lipid droplets in the cytoplasm.

Milk released in the first few days after parturition is called colostrum and has low lipid content but contains considerable quantities of antibodies.