Glands in general : easy and brief description

Glands:

Definition: glands are specialized epithelium which are formed by proliferation of epithelium into the underlying tissues

Parts of a gland:

Parenchyma: glandular portion which responsible for secretion

Stroma: it is the supporting portion of a gland which is formed by connective tissue

Classification of glandular epithelium

 According to presence or absence of duct: glands are two types: exocrine gland (gland with duct) and endocrine gland (gland without duct)

According to the mode of secretion :gland are three types

•         Merocrine: secretory granules leave the cell by exocytosis.  exm: pancreatic acinar cells secretion

•         Apocrine: secretion discharge with parts of apical cytoplasm. exm: lactating mammary glands   

•         Holocrine: secretory product is shed with the whole cell. exm: sebaceous gland                       

According the nature of secretion : glands are three types

•         Mucous : viscous secretin. exm: goblet cells

•         Serous: thin secretion. exm: parotid gland contain only serous acini

•         Seromucous: exm: submandibular glands

Distribution of different types of exocrine glands:

 According to the number of cells. Exocrine glands are two types

1) Uni-cellular: goblet cells

2) Multi-cellular: they are two types’ simple (single duct) and compound (more than one duct)

Simple (single duct)	Compound (more than one duct)
Simple tubular: G.Of L.intestine Simple acinar: G.Of penile part of urethra Simple coiled tubular : Sweat gland Simple bran. Acinar: Sebaceous gland Simple bran. Tubular: G of pylorus	Com. Bra. Tubular: Brunner’s gland Com. Acinaer g: pancreas Com. Tubuloacinar: Submandibular gland

Distribution of different types of endocrine glands:

Cord or clump type: ex: Adrenal glands

Follicular type: ex: Thyroid