Histology of thyroid Flashcards
What surrounds the thyroid gland?
A) A layer of adipose tissue
B) A thin connective tissue capsule
C) A cartilage sheath
D) A layer of smooth muscle
Answer: B) A thin connective tissue capsule
What is the functional unit of the thyroid gland?
A) Parafollicular cells
B) Colloid
C) Thyroid follicles
D) Trabeculae
Answer: C) Thyroid follicles
Where is the thyroid gland located?
A) Posterior to the trachea
B) Anterior to the neck, adjacent to the larynx and trachea
C) Inside the cranial cavity
D) Near the pancreas
Answer: B) Anterior to the neck, adjacent to the larynx and trachea
When does the thyroid gland begin to develop during gestation?
A) Week 2
B) Week 4
C) Week 8
D) Week 12
Answer: B) Week 4
The thyroid gland originates from which embryonic layer?
A) Mesoderm
B) Ectoderm
C) Endoderm
D) Neural crest cells
Answer: C) Endoderm
What is the name of the structure that forms as the thyroid primordium grows caudally?
A) Thyroid sinus
B) Thyroglossal duct
C) Laryngeal pouch
D) Parathyroid invagination
Answer: B) Thyroglossal duct
By which week of development do well-developed thyroid follicles contain colloid?
A) Week 10
B) Week 12
C) Week 14
D) Week 16
Answer: C) Week 14
What is the function of the thyroid follicle?
A) To store hormones and produce T3 and T4
B) To filter blood
C) To produce insulin
D) To secrete digestive enzymes
Answer: A) To store hormones and produce T3 and T4
What is the approximate weight of each lobe of the thyroid gland?
A) 5-10 g
B) 10-15 g
C) 20-30 g
D) 40-50 g
Answer: C) 20-30 g
What is contained inside the lumen of the thyroid follicle?
A) Blood plasma
B) Connective tissue
C) Colloid
D) Cartilage
Answer: C) Colloid
The thyroid follicle is lined by which type of epithelium?
A) Stratified squamous epithelium
B) Simple cuboidal or low columnar epithelium
C) Pseudostratified columnar epithelium
D) Transitional epithelium
Answer: B) Simple cuboidal or low columnar epithelium
What are the two types of cells found in the follicular epithelium?
A) Parafollicular and follicular cells
B) Chief and oxyphil cells
C) Hepatocytes and Kupffer cells
D) Beta and alpha cells
Answer: A) Parafollicular and follicular cells
What is the role of the parafollicular cells in the thyroid gland?
A) They produce insulin
B) They secrete digestive enzymes
C) They regulate calcium homeostasis
D) They filter waste
Answer: C) They regulate calcium homeostasis
How does the shape of follicular cells change with activity?
A) They become more prismatic during secretion and flatter at rest
B) They become rounder during secretion and elongated at rest
C) They do not change shape
D) They shrink when secreting hormones
Answer: A) They become more prismatic during secretion and flatter at rest
What feature is present on the surface of follicular epithelial cells?
A) Long cilia
B) Short microvilli
C) Flagella
D) Pseudopodia
Answer: B) Short microvilli
What is the primary function of follicular (principal) cells in the thyroid gland?
A) Production of insulin
B) Secretion of calcitonin
C) Production of thyroid hormones T3 and T4
D) Regulation of blood glucose levels
Answer: C) Production of thyroid hormones T3 and T4
What structures send trabeculae into the thyroid parenchyma?
A) Thyroid follicles
B) Connective tissue capsule
C) Lymphatic vessels
D) Nerve fibers
Answer: B) Connective tissue capsule
What type of staining reaction does colloid in the thyroid follicles show?
A) Hematoxylin-negative
B) PAS-positive
C) Eosin-negative
D) Silver stain-positive
Answer: B) PAS-positive
What is the location of the nucleus in follicular cells?
A) Basally located
B) Apically located
C) Peripherally located
D) Centrally located
Answer: D) Centrally located
Where is the Golgi apparatus found in follicular cells?
A) In the basal region
B) In the supranuclear region
C) Near the cell membrane
D) Distributed throughout the cytoplasm
Answer: B) In the supranuclear region
How do follicular cells obtain colloid for thyroid hormone secretion?
A) They release enzymes to break it down externally
B) They extend pseudopods into the lumen and take in colloid
C) They absorb it through active transport proteins
D) They rely on C cells to absorb the colloid
Answer: B) They extend pseudopods into the lumen and take in colloid
Where are T3 and T4 hormones released after processing?
A) Into the follicle lumen
B) Into the bloodstream from the basal side of the cell
C) Into the surrounding connective tissue
D) Into the lymphatic system
Answer: B) Into the bloodstream from the basal side of the cell
Where are parafollicular (C) cells located?
A) Inside the follicular lumen
B) In the periphery of the follicular epithelium, within the follicle basal lamina
C) In the thyroid capsule
D) In the interstitial spaces between follicles
Answer: B) In the periphery of the follicular epithelium, within the follicle basal lamina
What is the function of parafollicular (C) cells?
A) Production of T3 and T4
B) Secretion of calcitonin
C) Absorption of iodine
D) Regulation of glucose metabolism
Answer: B) Secretion of calcitonin
What is the primary function of calcitonin?
A) Regulation of blood glucose levels
B) Stimulation of thyroid hormone production
C) Regulation of calcium metabolism
D) Promotion of red blood cell production
Answer: C) Regulation of calcium metabolism
How do parafollicular (C) cells appear in routine H&E staining?
A) Dark-staining and clustered together
B) Pale-staining and found as solitary or small clusters of cells
C) Large and darkly stained
D) Similar in appearance to follicular cells
Answer: B) Pale-staining and found as solitary or small clusters of cells
What characterizes hyperthyroidism (Graves’ disease)?
A) Decreased secretion of thyroid hormones
B) Excessive release of thyroid hormones into circulation
C) Lack of iodine absorption
D) Shrinkage of the thyroid gland
Answer: B) Excessive release of thyroid hormones into circulation
What is a common cause of hypothyroidism?
A) Excessive iodine intake
B) Insufficient dietary iodine or autoimmune diseases
C) Overproduction of thyroid hormones
D) Parathyroid gland dysfunction
Answer: B) Insufficient dietary iodine or autoimmune diseases
What is the most common symptom of thyroid disease?
A) Hyperpigmentation
B) Hypoglycemia
C) Goiter (enlargement of the thyroid gland)
D) Hypertension
Answer: C) Goiter (enlargement of the thyroid gland)
What is another name for iodine-deficiency goiter?
A) Toxic goiter
B) Endemic goiter
C) Multinodular goiter
D) Autoimmune goiter
Answer: B) Endemic goiter
Which autoimmune disease is associated with hypothyroidism?
A) Graves’ disease
B) Hashimoto’s thyroiditis
C) Addison’s disease
D) Cushing’s syndrome
Answer: B) Hashimoto’s thyroiditis
What effect do low thyroid hormone levels have on TSH secretion?
A) Decrease TSH release
B) Increase TSH release
C) No effect on TSH levels
D) Suppress TSH completely
Answer: B) Increase TSH release
What is the structural boundary of each parathyroid gland?
A) Thick muscular layer
B) Cartilage sheath
C) Thin connective tissue capsule
D) Smooth muscle covering
Answer: C) Thin connective tissue capsule
What divides the parathyroid gland into poorly defined lobules?
A) Trabeculae
B) Septa from the capsule
C) Follicular cells
D) Blood vessels
Answer: B) Septa from the capsule
What is the embryological origin of the superior parathyroid glands?
A) First pharyngeal pouch
B) Second pharyngeal pouch
C) Third pharyngeal pouch
D) Fourth pharyngeal pouch
Answer: D) Fourth pharyngeal pouch
The inferior parathyroid glands originate from which embryonic structure?
A) First pharyngeal pouch
B) Second pharyngeal pouch
C) Third pharyngeal pouch
D) Fourth pharyngeal pouch
Answer: C) Third pharyngeal pouch
What happens to thyroid cells in Hashimoto’s thyroiditis?
A) They undergo hypertrophy
B) They increase hormone production
C) They undergo apoptosis and follicular destruction
D) They produce excess calcitonin
Answer: C) They undergo apoptosis and follicular destruction
When do oxyphil cells of the parathyroid gland differentiate?
A) During fetal development
B) At birth
C) At puberty
D) During old age
Answer: C) At puberty
What is the main function of principal (chief) cells in the parathyroid gland?
A) Production of calcitonin
B) Regulation and secretion of parathyroid hormone (PTH)
C) Storage of thyroid hormones
D) Protection against infections
Answer: B) Regulation and secretion of parathyroid hormone (PTH)
What is the role of oxyphil cells in the parathyroid gland?
A) Secretion of parathyroid hormone (PTH)
B) Production of calcitonin
C) No known secretory function
D) Regulation of calcium levels
Answer: C) No known secretory function
What is the function of PTH (parathyroid hormone)?
A) Increases calcium levels in the blood
B) Decreases calcium levels in the blood
C) Increases sodium levels in the blood
D) Decreases sodium levels in the blood
Answer: A) Increases calcium levels in the blood
How does PTH increase calcium levels in the blood?
A) By promoting calcium release from bone and increasing vitamin D3 formation in the kidney
B) By stimulating thyroid follicular cells
C) By decreasing the absorption of calcium in the intestines
D) By preventing calcium reabsorption in the kidneys
Answer: A) By promoting calcium release from bone and increasing vitamin D3 formation in the kidney
How do oxyphil cells appear in comparison to principal cells?
A) Smaller and basophilic
B) Larger and strongly acidophilic
C) Smaller and pale-staining
D) Identical in size and staining properties
Answer: B) Larger and strongly acidophilic
What organelles are abundant in oxyphil cells?
A) rER and Golgi
B) Secretory vesicles
C) Mitochondria
D) Lysosomes
Answer: C) Mitochondria
Where are the adrenal glands located?
A) In the thoracic cavity
B) In the pelvic region
C) In the retroperitoneal space of the abdominal cavity
D) Behind the thyroid gland
Answer: C) In the retroperitoneal space of the abdominal cavity
How are oxyphil cells arranged within the parathyroid gland?
A) In follicles
B) As a single continuous layer
C) Singly or in clusters
D) Surrounding blood vessels
Answer: C) Singly or in clusters
What type of hormones do the adrenal glands secrete?
A) Only peptide hormones
B) Only steroid hormones
C) Only catecholamines
D) Both steroid hormones and catecholamines
Answer: D) Both steroid hormones and catecholamines
What structure covers the adrenal gland?
A) A thick connective tissue capsule
B) A layer of smooth muscle
C) A fibrous cartilage sheath
D) A layer of squamous epithelium
Answer: A) A thick connective tissue capsule
What is the embryonic origin of the adrenal cortex?
A) Neural crest cells
B) Mesodermal mesenchyme
C) Endoderm
D) Ectoderm
Answer: B) Mesodermal mesenchyme
What is responsible for the strong acidophilia of oxyphil cells?
A) Presence of rER
B) Presence of mitochondria
C) Large glycogen granules
D) High lipid content
Answer: B) Presence of mitochondria
