Gland

Endocrine glands are ductless and secrete their products, hormones, directly into interstitial spaces to be taken up into the bloodstream.

This ingrowth may in the beginning possess a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated.

[3] As growth proceeds, the column of cells may split or give off offshoots, in which case a compound gland is formed.

In many glands, the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division.

Exocrine glands secrete their products through a duct onto an outer or inner surface of the body, such as the skin or the gastrointestinal tract.

This image shows some of the various possible glandular arrangements. These are the simple tubular, simple branched tubular, simple coiled tubular, simple acinar, and simple branched acinar glands.
This image shows some of the various possible glandular arrangements. These are the compound tubular, compound acinar, and compound tubulo-acinar glands.
Here is a diagram that shows the differences between endocrine and exocrine glands. The major difference is that exocrine glands secrete substances out of the body and endocrine glands secrete substances into capillaries and blood vessels.
Histopathology of sclerosing adenosis of the breast.