Page 518 - Anatomy and Physiology of Farm Animals, 8th Edition

Anatomy and Physiology of the Mammary Glands / 503

The parenchyma of the lactating mam- lactiferous sinus. The lactiferous sinus is
mary gland consists of secretory tissue and
sometimes described as being divided into
VetBooks.ir the ducts of the gland (Fig. 29‐1). The a large cavity within the quarter itself, the
secretory units, the alveoli, are lined by a
gland cistern, and a smaller cavity within
simple epithelium that varies from colum- the associated teat called the teat cistern
nar to cuboidal in height. The alveoli are (Fig. 29‐1). The demarcation between
the chief structures for actual milk produc- gland cistern and teat cistern frequently is
tion, although the initial portion of the marked by a circular ridge (annulus) that
associated duct is also lined with secretory contains a vein and some smooth muscle
epithelium. fibers.
The various small initial ducts converge The wall of the empty cistern contains
to form larger ducts, and these converge to numerous overlapping longitudinal and
form yet larger ones, all of which eventu- circular folds that are obliterated through
ally terminate in a large single basin, the expansion of the wall when it is full of milk.

Cuboidal epithelium Myoepithelial cells

Interlobular duct

Intralobular duct

Alveoli
Interlobular
duct
Intralobular duct

Gland cistern

Lactiferous sinus

Teat cistern

Papillary duct
TEAT

Ostium papillae
Figure 29-1. Anatomy of the bovine udder.