Microscopic Anatomy Practice Questions

Q: Which area in the spleen is considered *primarily* thymus-dependent?

Periarteriolar lymphoid sheath (PALS). ***Periarteriolar lymphoid sheath (PALS)*** - PALS is the **T-cell zone** of splenic white pulp, containing predominantly **T-lymphocytes** arranged around central arterioles. [2] - This area is **thymus-dependent** as it houses mature T cells that have undergone thymic selection and education, making it the primary thymus-dependent area of the spleen. [1] *Mantle layer* - The mantle layer consists of **naïve B lymphocytes** that surround the germinal center within splenic follicles. - This area is **thymus-independent** and primarily involved in **B-cell responses** to antigens. *Malpighian corpuscle* - Also known as **splenic follicles** or white pulp, this area primarily functions as **B-cell aggregation zones**. - While containing both B and T cell areas, it's predominantly **thymus-independent** with its main role being B-cell activation and antibody production. *None of the options* - This option is incorrect because PALS clearly represents the primary **thymus-dependent area** in the spleen. - The spleen definitively contains thymus-dependent zones where **T-cell activation** and proliferation occur, specifically the PALS. [1]

Q: Blood testis barrier in testis is formed by?

Sertoli cells. ***Sertoli cells*** - **Sertoli cells** form tight junctions with each other, creating the **blood-testis barrier** [1] - This barrier divides the seminiferous epithelium into **basal and adluminal compartments** [1] - Essential for protecting developing **germ cells** from immune attack and maintaining a specialized microenvironment for **spermatogenesis** [1] - The tight junctions between Sertoli cells are among the tightest in the human body *Granulosa cells* - **Granulosa cells** are found in the **ovary**, not the testis - They surround the oocyte in ovarian follicles and produce **estrogen** - Completely unrelated to testicular structure or function *Germ cells* - **Germ cells** (spermatogonia, spermatocytes, spermatids, spermatozoa) are the developing sperm cells [1] - They are **protected by** the blood-testis barrier, not forming it [1] - Located within the seminiferous tubules but do not create barrier structures [1] *Leydig cells* - **Leydig cells** are interstitial cells located in the connective tissue **between seminiferous tubules** - Their primary function is production of **testosterone**, not forming barriers [2] - They are outside the seminiferous tubules and not involved in barrier formation [2]

Q: Oxyntic cells are present in -

Body. ***Body*** - **Oxyntic cells**, also known as **parietal cells**, are predominantly located in the **fundus and body** of the stomach [1], [2]. - These cells are responsible for secreting **hydrochloric acid (HCl)** and **intrinsic factor**, which are crucial for digestion and vitamin B12 absorption [1]. - The gastric glands in the body contain the highest concentration of parietal cells [2]. *Pylorus* - The pylorus is the distal part of the stomach that connects to the duodenum. - It primarily contains **G cells**, which secrete **gastrin**, a hormone that stimulates HCl secretion from parietal cells [3]. - Pyloric glands contain mainly mucus-secreting cells, with few or no parietal cells [2]. *Cardia* - The cardia is the region near the gastroesophageal junction (entrance of the stomach). - This area primarily contains **cardiac glands** with mucus-secreting cells that protect the esophageal lining from gastric acid reflux. - Parietal cells are sparse or absent in the cardia [2]. *None of the options* - This option is incorrect because the **body of the stomach** is the correct location for oxyntic cells.

Q: Blood tissue barrier in testis is formed by?

Adjacent Sertoli cells with basal lamina. ***Adjacent Sertoli cells with basal lamina*** - The **blood-testis barrier** is primarily formed by **tight junctions** between adjacent **Sertoli cells**, which divide the seminiferous epithelium into basal and adluminal compartments [1]. - The **basal lamina** of the seminiferous tubule also contributes to this barrier, regulating the passage of substances from the interstitial fluid to the basal compartment [1]. *Basal lamina & interstitial cells* - While the **basal lamina** is part of the barrier, **interstitial cells (Leydig cells)** are located outside the seminiferous tubules and are primarily involved in **testosterone production**, not barrier formation [1]. - **Interstitial cells** are part of the connective tissue between the tubules and do not form tight junctions that would restrict molecular movement into the seminiferous epithelium. *Basal lamina & spermatogonia* - **Spermatogonia** are germ cells located in the **basal compartment** of the seminiferous tubule, *beneath* the Sertoli cell tight junctions [1]. - They are able to cross the barrier as they differentiate and move into the adluminal compartment, but they do not form the barrier itself. *Basal lamina & leydig cells* - As mentioned previously, **Leydig cells** (interstitial cells) are responsible for **androgen synthesis** and are located outside the seminiferous tubule [2]. - They do not form components of the physical blood-testis barrier.

Q: Which layer of the skin contains abundant desmosomes?

Stratum spinosum. ***Stratum spinosum*** - This layer is characterized by abundant **desmosomes**, which connect keratinocytes and give them a "spiny" appearance when stained, hence its name. - The desmosomes provide **strong cell-to-cell adhesion**, crucial for the skin's barrier function and mechanical strength [1]. *Stratum corneum* - This outermost layer primarily consists of **dead, flattened keratinocytes** (corneocytes) filled with keratin [1]. - While desmosomes are present, they are in a process of degradation and are not as numerous or prominent as in the stratum spinosum. *Stratum granulosum* - This layer is known for the presence of **keratohyalin granules** and **lamellar granules**, which are involved in keratinization and lipid secretion, respectively [1]. - While cells here still have desmosomes, their primary function shifts towards preparing for the final differentiation into the stratum corneum. *Stratum basale* - This is the deepest layer, containing **mitotically active keratinocytes** that attach to the basement membrane via **hemidesmosomes**. - While desmosomes are present to connect these basal cells to each other and to the cells of the stratum spinosum, they are not as abundant or characteristic as in the stratum spinosum [1].

Q: Podocytes are seen in -

Bowman's capsule. **Bowman's capsule** - **Podocytes** are specialized epithelial cells that form the **visceral layer** of Bowman's capsule. They have foot processes (pedicels) that interdigitate to form slit diaphragms, which are crucial for the **filtration barrier** of the glomerulus [1]. - These cells facilitate the selective passage of water and small solutes from the blood into Bowman's space, while preventing the filtration of large proteins and blood cells. *Proximal convoluted tubule* - The **proximal convoluted tubule** is primarily involved in the **reabsorption** of essential nutrients, ions, and water from the filtrate back into the bloodstream [1]. - Its cells are characterized by a **brush border** (microvilli) and numerous mitochondria, indicating high metabolic activity, and are not podocytes [1]. *Distal convoluted tubule* - The **distal convoluted tubule** plays a role in fine-tuning the reabsorption of ions and water, under the influence of hormones like **aldosterone** and **ADH**. - Its cells lack the specialized foot processes and filtration function characteristic of podocytes. *Collecting tubule of the kidney* - The **collecting tubule** (or collecting duct) is involved in regulating water reabsorption and acid-base balance, responding to **ADH** to concentrate urine. - Its epithelial cells are principal cells and intercalated cells, which are different in structure and function from podocytes.

Q: Elongated rete pegs are seen in:

Attached gingiva. ***Attached gingiva*** - The **attached gingiva** is characterized by a **keratinized stratified squamous epithelium** with prominent, **elongated rete pegs** that interdigitate with the underlying connective tissue. - This anatomical feature provides a strong attachment to the underlying bone, contributing to its immobility and resistance to functional stress. *Alveolar mucosa* - The **alveolar mucosa** is composed of a **non-keratinized stratified squamous epithelium** with a relatively smooth interface between the epithelium and connective tissue, exhibiting short or absent rete pegs. - Its loose connective tissue and lack of keratinization make it highly movable and less resistant to abrasion compared to attached gingiva. *Floor of the mouth* - The epithelium of the **floor of the mouth** is typically **non-keratinized**, thin, and relatively smooth, featuring **short or flattened rete pegs**. - This characteristic allows for flexibility and is involved in salivary gland secretions, lacking the robust interdigitations seen in attached gingiva. *Buccal mucosa* - **Buccal mucosa** is lined by **non-keratinized stratified squamous epithelium** with **short, irregular rete pegs**, making it flexible and well-adapted for chewing and speech. - It serves as a protective lining for the inner cheek and lacks the tightly interdigitated, elongated rete pegs characteristic of keratinized tissues like attached gingiva.

Q: In which of the following organs is the Space of Disse found?

Liver. ***Liver*** - The **Space of Disse**, also known as the perisinusoidal space, is a crucial area located in the **liver** between the sinusoidal endothelial cells and the hepatocytes [1]. - This space is involved in the exchange of substances between the blood and liver cells, and it contains **hepatic stellate cells** (Ito cells) which play a role in retinoid storage and liver fibrosis [1]. *Bone* - Bone tissue contains various spaces like bone marrow cavities and lacunae, but not the **Space of Disse**. - Its primary functions are structural support, hematopoiesis, and mineral storage. *Lymph node* - Lymph nodes are part of the immune system and contain sinuses for lymph flow, but not the **Space of Disse**. - They function in filtering lymph and initiating immune responses. *Spleen* - The spleen is involved in filtering blood and immune surveillance, containing red and white pulp, but lacks the **Space of Disse**. - It plays a role in red blood cell turnover and immune responses.

Q: Which one of the following possesses a distinct internal elastic lamina?

Muscular artery. ***Muscular artery*** - **Muscular arteries** have a well-developed, distinct **internal elastic lamina** [1] between the tunica intima and tunica media. - This lamina helps to maintain blood pressure and regulate blood flow to various organs. *Capillary* - **Capillaries** are the smallest blood vessels, consisting only of an **endothelial layer** [1] and basement membrane. - They lack a distinct internal elastic lamina, as their primary function is efficient **exchange of nutrients** [2] and waste products. *Metarteriole* - **Metarterioles** are small-diameter vessels leading to capillaries, characterized by scattered **smooth muscle cells** [1] rather than a continuous muscular layer. - They do not possess a distinct internal elastic lamina; their structure is transitional between arterioles and capillaries. *Arteriole* - **Arterioles** generally have a thinner and less distinct elastic lamina compared to muscular arteries [1], or it may be entirely absent in the smallest arterioles. - Their primary role is to regulate **blood flow** and **peripheral resistance** through constriction and dilation of their smooth muscles.

Question 1

Which area in the spleen is considered *primarily* thymus-dependent?

Accepted Answer

Periarteriolar lymphoid sheath (PALS)

Answer

Mantle layer

Answer

Malpighian corpuscle

Answer

None of the options

Question 2

Blood testis barrier in testis is formed by?

Accepted Answer

Sertoli cells

Answer

Germ cells

Answer

Leydig cells

Answer

Granulosa cells

Question 3

Oxyntic cells are present in -

Accepted Answer

Body

Answer

Pylorus

Answer

Cardia

Answer

None of the options

Question 4

Blood tissue barrier in testis is formed by?

Accepted Answer

Adjacent Sertoli cells with basal lamina

Answer

Basal lamina & interstitial cells

Answer

Basal lamina & spermatogonia

Answer

Basal lamina & leydig cells

Question 5

Which layer of the skin contains abundant desmosomes?

Accepted Answer

Stratum spinosum

Answer

Stratum basale

Answer

Stratum corneum

Answer

Stratum granulosum

Question 6

Podocytes are seen in -

Accepted Answer

Bowman's capsule

Answer

Proximal convoluted tubule

Answer

Distal convoluted tubule

Answer

Collecting tubule of the kidney

Question 7

Where is the density of the parafollicular cells (C-cells) in the thyroid gland at its maximum?

Accepted Answer

Juncture of the upper one-third and lower two-thirds of the gland

Answer

Isthmus

Answer

Upper one-third of the gland

Answer

Posterior part

Question 8

Elongated rete pegs are seen in:

Accepted Answer

Attached gingiva

Answer

Alveolar mucosa

Answer

Floor of the mouth

Answer

Buccal mucosa

Question 9

In which of the following organs is the Space of Disse found?

Accepted Answer

Liver

Answer

Bone

Answer

Lymph node

Answer

Spleen

Question 10

Which one of the following possesses a distinct internal elastic lamina?

Accepted Answer

Muscular artery

Answer

Arteriole

Answer

Capillary

Answer

Metarteriole

Microscopic Anatomy — MCQs

Microscopic Anatomy — MCQs

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