secretory tubule

In apocrine glands, the secretory tubule is branched and single-layered, whereas it is unbranched, coiled, and double-layered in eccrine glands.

The apocrine gland comprises a glomerulus of secretory tubules and an excretory duct that opens into hair follicle; on occasion, an excretory duct opens to the skin surface next to the hair.

Eccrine glands are composed of an intreaepidermal spiral duct, the "acrosyringium"; a dermal duct, comprising a straight and coiled portion; and a secretory tubule, coiled deep in the dermis or hypodermis.

Unlike eccrine secretory tubules, secretory tubules of the apocrine gland are single-layered (lacking ductal cells), vary in diameter from place to place, and sometimes branch off into multiple ducts.

This defense is usually induced through contact of the proteins of the liquid white secretions of the white secretory tubule 1 of a male's accessory glands with the female's spermathecal duct (the process of which forms a spermatophore).