Histology of Chief and Oxyphil Cells

Questions and Answers

Which type of cells in the islets of Langerhans is primarily responsible for decreasing blood glucose levels?

D cells

C cells

B cells (correct)

A cells

What is unique about the granules of B cells in the islets of Langerhans?

They are polygonal in shape.

They are large with a dense core.

They lack a membrane

They contain rectangular crystals of insulin in complex with zinc. (correct)

What role do gap junctions play in the islets of Langerhans?

They synthesize polypeptides.

They prevent the exchange of neurotransmitters.

They facilitate the transfer of ionic changes between cells. (correct)

They are involved in the secretion of glucagon.

Which cells in the islets of Langerhans are predominantly located in the peripheral region of the islet and produce glucagon?

A cells Signup and view all the answers

What type of cells in the islets of Langerhans make up the majority at 70% and are responsible for insulin production?

B cells Signup and view all the answers

What component of the cell structure is well-developed in the islet cells responsible for synthesizing polypeptides?

Golgi apparatus Signup and view all the answers

What is a characteristic feature of chief (principal) cells?

They have abundant rough endoplasmic reticulum. Signup and view all the answers

How do oxyphil cells differ from chief cells?

Oxyphil cells have more acidophilic cytoplasm than chief cells. Signup and view all the answers

What is the primary function of parathyroid hormone (PTH) produced by chief cells?

It increases the blood calcium level. Signup and view all the answers

What describes the structure of the islets of Langerhans?

They are surrounded by a fine capsule of reticular fibers. Signup and view all the answers

Which of the following statements about oxyphil cells is true?

They may represent immature chief cells. Signup and view all the answers

What regulates the secretion of parathyroid hormone (PTH)?

The serum calcium level. Signup and view all the answers

What is the histological appearance of oxyphil cells under light microscopy?

They are larger and have small densely stained nuclei. Signup and view all the answers

What feature is unique to chief cells compared to other parathyroid cells?

Presence of glycogen granules. Signup and view all the answers

Study Notes

Chief (Principal) Cells

Most numerous cells in the parenchyma of parathyroid glands.
Small, polygonal shape with central rounded nuclei and pale, slightly acidophilic cytoplasm due to glycogen content.
Ultrastructural features include:
- Juxtanuclear Golgi complex.
- Elongated mitochondria with numerous cristae.
- Abundant rough endoplasmic reticulum (rER).
- Presence of lipofuscin pigment, glycogen granules, and lipid droplets.
- Smaller dense granules that contain parathyroid hormone (PTH).
Function of PTH:
- Increases blood calcium levels, antagonistic to calcitonin hormone.
- Promotes phosphate excretion, lowering blood phosphate levels.
- Secretion regulated by serum calcium levels.

Oxyphil Cells

Fewer in number and larger than chief cells, with small, deeply stained nuclei.
Cytoplasm more acidophilic, present singly or in clusters, increasing in number with age.
Ultrastructural characteristics:
- Abundant mitochondria and small Golgi complex with minimal rER.
- Contains glycogen and lipid droplets among mitochondria.
- Presence of secretory granules.
Function: Unclear, potentially considered as immature chief cells.

Islets of Langerhans

Endocrine portion of the pancreas comprised of pale rounded clusters of epithelial cells within dense exocrine pancreatic acini.
More than one million islets in the human pancreas, predominantly found in the tail region.
Structure:
- Surrounded by a fine capsule of reticular fibers, separating from exocrine tissue.
- Parenchyma features lightly stained, polygonal or rounded cells organized in cords, interspersed with fenestrated blood capillaries.
Four cell types identified using immunocytochemistry: A, B, D, and F cells.
Ultrastructural features:
- Cells exhibit characteristics of polypeptide synthesizing (APUD) cells.
- Contain rER, well-developed Golgi apparatus, and specific secretory granules, with large vesicular nuclei.
Cell types in Islets of Langerhans:
- A Cells (α cells):
  - Comprise around 20% of islet cells, located mostly at the periphery.
  - Produce glucagon, which increases blood glucose levels by converting glycogen to glucose.
- B Cells (β cells):
  - Make up about 70% of islet cells, found centrally.
  - Produce insulin, lowering blood glucose levels by converting glucose to glycogen.
- D Cells: Additional unspecified functional characteristics.

Description

This quiz focuses on the histological features of Chief (Principal) and Oxyphil cells. It covers their structure, cytoplasm characteristics, and organelle composition at both light and electron microscopy levels. Dive into the details of these cell types and their significance in the parenchyma.