Definition

Noun: * Pars Nervosa: The posterior lobe of the pituitary gland (hypophysis). It is primarily composed of neural tissue and serves as a storage and release site for hormones (oxytocin and vasopressin) produced by the hypothalamus, rather than synthesizing hormones itself.

Usage

• The term is used in anatomical, medical, and endocrinological contexts to specify the neural part of the pituitary gland.
• It is often contrasted with the (anterior pituitary) and (intermediate lobe).

Examples

• In human anatomy, the pars nervosa is connected to the hypothalamus via the pituitary stalk.
• The hormones stored in the pars nervosa are critical for regulating water balance and uterine contractions.
• A magnetic resonance imaging (MRI) scan can clearly distinguish the pars nervosa from the anterior pituitary.

Advanced Usage

• Histological Context: When examining tissue under a microscope, the pars nervosa is identifiable by the presence of Herring bodies, which are the terminal ends of axons from the hypothalamus.
• Functional Description: While often described as "primarily glandular in nature" in some older texts, modern understanding emphasizes its role as a neurohemal organ—a neural structure that releases hormones into the bloodstream.

Variants and Related Words

• Neurohypophysis: This is a direct synonym for and is frequently used interchangeably in medical literature.
• Posterior Pituitary: A common, less technical term for the .
• Pars Distalis: Refers to the anterior lobe of the pituitary gland, which is truly glandular and synthesizes its own hormones.
• Infundibulum: The pituitary stalk that connects the pars nervosa to the hypothalamus.

Synonyms

• Neurohypophysis
• Posterior lobe of the pituitary
• Posterior pituitary gland

Notes on Meaning

The provided reference context describes the pars nervosa as "primarily glandular in nature." This is an older or more generalized classification. In precise modern terminology, its neural origin and storage function are emphasized, distinguishing it from the truly glandular anterior pituitary (pars distalis). The key meaning is its identity as the neural component of the pituitary gland.

Noun

1. the posterior lobe of the pituitary body; primarily glandular in nature