Page 756 - Atlas of Histology with Functional Correlations

SECTION 1 • Hormones and Pituitary Gland

Consists of cells, tissues, and organs that produce blood-borne chemicals

Consists of ductless glands, arranged in cords and clumps, and surrounded by
capillaries
Hormones enter connective tissue and then blood or lymphatic circulation
Hormones interact with target organs that have specific receptors
Hormone receptors located on cell membrane, in cytoplasm, or in nucleus

Nonsteroid hormone receptors located on cell surface
Proteins and polypeptide hormones use second messenger (cAMP) to
activate responses

Steroid and thyroid hormones enter cells and influence gene expression in
nucleus
There are complete endocrine organs and mixed organs with endocrine cells
and tissues

EMBRYOLOGIC DEVELOPMENT OF

HYPOPHYSIS (PITUITARY GLAND)

Has dual embryologic origin, epithelial and neural
Epithelial portion develops from pharyngeal roof and Rathke pouch

Pouch detaches and becomes the cellular portion, adenohypophysis (anterior
pituitary)
Downgrowth of brain forms the neural portion, neurohypophysis (posterior
pituitary)

Neurohypophysis remains attached to hypothalamus by a neural stalk,
infundibulum
Neurons in hypothalamus control release of hormones from adenohypophysis

SUBDIVISIONS OF HYPOPHYSIS

Adenohypophysis (anterior pituitary) has three subdivisions

Pars distalis is the largest part

755