L27. Histology - Microanatomy of Endocrine Glands. Introduction and The Hypophysis

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Questions and Answers

Which of the following is NOT a primary division of the pituitary gland?

Pars intermedia (correct)

Adenohypophysis

Pars distalis

Neurohypophysis

The pars distalis is characterized by which of the following?

Direct neural control from the hypothalamus

Secretion of hormones directly into the bloodstream using a vascular pattern (correct)

A characteristic palisade arrangement of cells

A large number of Herring bodies

Which of the following BEST describes the developmental origin of the neurohypophysis?

Formed as a pouch from the developing pharynx

Derived from neural tissue from the diencephalon (correct)

Developed from a fusion of placodal tissue.

Derived from an evagination of the oral ectoderm

What is the primary function of the cells found in the pars intermedia?

To synthesize and secrete melanocyte-stimulating hormone (MSH). Signup and view all the answers

The pineal gland is characterized by which unique histological feature?

The presence of brain sand (corpora arenacea) Signup and view all the answers

Which statement accurately describes the control of the pars nervosa?

It's controlled by direct neural input from the hypothalamus. Signup and view all the answers

Which of the following is NOT a characteristic feature of the thyroid gland?

Secretes exclusively peptide-based hormones. Signup and view all the answers

Which of the following accurately describes the most common method of hormone transport throughout the body?

Circulation through the vasculature to distant target cells. Signup and view all the answers

What cellular structure is primarily responsible for the synthesis of peptide, protein and glycoprotein hormones?

Rough endoplasmic reticulum Signup and view all the answers

Which of the following represents an autocrine effect of a hormone?

Hormone action on the same cells that produced the hormone. Signup and view all the answers

Where are steroid hormones primarily synthesized within an endocrine cell?

Smooth endoplasmic reticulum Signup and view all the answers

Which of the following is NOT a class of compounds considered to be hormones?

Polysaccharides Signup and view all the answers

How does the endocrine system primarily communicate with target cells?

Through the release of hormones into the vasculature. Signup and view all the answers

What is the primary function of the Golgi complex in the formation of peptide hormones?

Packaging the synthesized hormone in secretory vesicles Signup and view all the answers

In comparison to paracrine signaling, what distinguishes endocrine signaling?

It involves the transport of substances via the bloodstream. Signup and view all the answers

Where are hormones stored directly before being released from the cell?

Secretory vesicles Signup and view all the answers

Which component of the hypophysis is derived from an invagination of the oral ectoderm?

Adenohypophysis Signup and view all the answers

Which of the following best describes the blood supply to the pars nervosa?

Mainly supplied by the inferior hypophyseal arteries. Signup and view all the answers

From which embryonic structure does the neurohypophysis originate?

Floor of the diencephalon Signup and view all the answers

What is the primary function of the hypophyseal portal system?

To carry the major blood supply to the anterior lobe Signup and view all the answers

What is the nature of the capillaries found in the pars distalis?

Wide sinusoids with fenestrated endothelium Signup and view all the answers

Which of the following is NOT a part of the adenohypophysis?

Pars nervosa Signup and view all the answers

Which arteries contribute to the blood supply of the hypophyseal portal system?

Superior hypophyseal arteries only Signup and view all the answers

Where do the fenestrated capillaries that supply the pars nervosa drain?

Hypophyseal veins Signup and view all the answers

What is the origin of the cells that form the adenohypophysis?

Oral ectoderm Signup and view all the answers

Which of the following structures receives blood supply directly from the superior hypophyseal arteries?

Median eminence and infundibulum Signup and view all the answers

What is the primary role of the substances acting on anterior pituitary cells?

To modulate the activity of hypothalamic cells regulating those cells Signup and view all the answers

Which statement correctly describes the pars intermedia in humans?

It may contain remnants of Rathke’s pouch Signup and view all the answers

What major cell type is predominantly found in the neurohypophysis?

Pituicytes Signup and view all the answers

What is the significance of Herring bodies in the neurohypophysis?

They contain aggregates of neurosecretory material Signup and view all the answers

What is largely unknown about the functional significance of the pars intermedia in humans?

The specific endocrine signals it generates Signup and view all the answers

Which cells in the pars distalis are responsible for synthesizing and secreting somatotropin?

Somatotropes Signup and view all the answers

What is the primary function of lactotropes in the endocrine system?

Assist in mammary gland development Signup and view all the answers

Which type of hormone does thyrotrope produce and what is its primary function?

Thyrotropic hormone; stimulates production of thyroid hormone Signup and view all the answers

Which staining property is characteristic of basophils in histological preparations?

Basophilic in H&E and blue in trichrome Signup and view all the answers

What are gonadotropes mainly responsible for producing?

Luteinizing and follicle-stimulating hormones Signup and view all the answers

What does the term 'pars distalis' refer to in the context of endocrine glands?

The anterior lobe of the pituitary gland Signup and view all the answers

Which hormone is NOT produced by the cells found in the pars distalis?

Adrenocorticotropic hormone Signup and view all the answers

In a transmission electron micrograph, what distinguishes different types of endocrine cells?

Morphology of secretory granules and other features Signup and view all the answers

How do lactotropes contribute to the function of the mammary glands?

By stimulating milk synthesis Signup and view all the answers

Which of the following hormones is specifically linked to reproductive functions?

Luteinizing hormone Signup and view all the answers

Study Notes

Microanatomy of Endocrine Glands I: Introduction and the Hypophysis

Learning Objectives: Describe the microanatomy and functions of the pituitary gland (hypophysis), list the two primary and five secondary divisions of the pituitary gland, describe the developmental origins of the two primary divisions, describe the pars distalis, pars intermedia, and pars nervosa, compare and contrast hypothalamic control of the pars nervosa and pars distalis, describe the microanatomy and functions of the pineal gland, describe the thyroid, parathyroid, and adrenal glands.

Pituitary Gland (Hypophysis)

Relationships: Attached to the base of the brain by the infundibular stalk, lies within the sella turcica, a depression of the sphenoid bone, and is covered partly by the diaphragma sellae, part of the dura mater.
Components and Divisions: Adenohypophysis (pars distalis, pars tuberalis, pars intermedia), Neurohypophysis (pars nervosa, infundibulum).
Development: Rathke's pouch, an invagination of the oral ectoderm, gives rise to the adenohypophysis, Neurohypophysis is formed by a down growth from the floor of the diencephalon (neural ectoderm).
Blood Supply: Inferior hypophyseal arteries supply the pars nervosa. Superior hypophyseal arteries supply the hypophyseal portal system. Portal vessels supply the anterior lobe. Secondary capillary plexus in pars distalis.

Hypothalamo-Hypophyseal Tract

Control of Adenohypophysis: Hypothalamic fibers from specific hypothalamic areas (tuberal nuclei), which terminate in the infundibular stalk. These neurons produce releasing/inhibitory factors, carried to adenohypophysis via hypophyseal portal vessels.

Adenohypophysis (Anterior Pituitary)

Pars Distalis: Makes up about 75% of the pituitary, contains anastomosing cords of cells separated by fenestrated capillaries with wide lumen. Cell types (acidophils, basophils, chromophobes). Cell types can be distinguished by staining characteristics.
- Acidophils: Somatotropes (growth hormone), lactotropes (prolactin).
- Basophils: Thyrotropes (thyroid-stimulating hormone), gonadotropes (follicle-stimulating hormone, luteinizing hormone), corticotropes (proopiomelanocortin).
Pars Intermedia: Poorly developed in humans, may show a remnant of Rathke's pouch, contains colloid-filled cysts, chromophobes, and basophils. Functional significance largely unknown.

Neurohypophysis (Posterior Pituitary)

Pituicytes: Major cell type, resemble astroglia.
Hormones: Oxytocin (uterine smooth muscle and mammary gland myoepithelial cells), Antidiuretic hormone (ADH; distal tubules and collecting ducts of kidney).
Herring Bodies: Aggregates of neurosecretory material.
Hormone Packaging: Packaged in vesicles that contain ATP and neurophysin.

Additional Endocrine Glands

Pineal Gland (Epithalamus): Location, appearance, and histological organization. Cell types and functions (melatonin). Histological diagnostic features. Comparison with other endocrine glands.
Thyroid Gland: Appearance, location, and histological organization. Cell types and their functions. Thyroid follicles with follicular cells making up the epithelium. Lumina content (colloidal). Relationship with the vasculature. Thyroglobulin synthesis and processing. Parafollicular cells (C cells) location, function, and the mechanism controlling secretion.
Parathyroid Gland: Appearance, location, and histological organization, cell types and functions. Characteristic histological features and age-related changes. Control mechanism of secretion.
Adrenal Gland: Appearance, location, and histological organization. Organization of adrenal cortex (zones). Course of blood vessels and blood flow within the adrenal gland. Histological organization of the adrenal medulla. Cell types and products within the adrenal medulla.

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Description

Explore the microanatomy and functions of the pituitary gland and its components in this quiz. Learn about the divisions, developmental origins, and the relationships of the glands such as the pineal, thyroid, parathyroid, and adrenal glands. Test your knowledge on hypothalamic control and the specific roles of different zones within the pituitary.