Histology Practice Questions

Q: Which of the following layers of epidermis is known as "prickle layer"?

Stratum spinosum. ***Stratum spinosum*** - This layer is called the **"prickle layer"** due to the presence of **desmosomes** which provide strong cell-to-cell adhesion, making the cells appear spiny or "prickly" under a microscope due to the shrinkage of cells during histological preparation. [1] - It consists of several layers of polyhedral cells, rich in **keratin filaments**, which contribute to the skin's strength and flexibility. *Stratum basale* - This is the **deepest layer** of the epidermis, responsible for continuous cell division and renewal of the epidermis. [1] - It contains **melanocytes** and **Merkel cells** in addition to keratinocytes, but its appearance is not prickly. [1] *Stratum granulosum* - This layer is characterized by the presence of **keratohyalin granules** and **lamellar granules**. [2] - Cells in this layer begin to flatten and their nuclei and organelles start to disintegrate as they move closer to the skin surface. *Stratum corneum* - This is the **outermost layer** of the epidermis, composed of flattened, dead keratinocytes called corneocytes, which form a protective barrier. [1] - It is known for its **tough, resistant nature** and ability to prevent water loss and protect against external damage.

Q: Which of the following is true about keratinocytes?

Ectoderm derived cell. ***Ectoderm derived cell*** - Keratinocytes originate from the **ectoderm**, one of the three primary germ layers in embryonic development, which gives rise to the epidermis. - This ectodermal origin is fundamental to their role in forming the protective outer layer of the skin. *Differentiate in basal layer* - Keratinocytes in the **basal layer (stratum basale)** are primarily responsible for **proliferation** (cell division) rather than differentiation. - **Differentiation** into flattened, keratin-filled cells occurs as they migrate upwards through the epidermal layers. *Mature in basal layer* - Maturation, which involves the accumulation of **keratin** and the loss of organelles, primarily occurs in the **upper layers** of the epidermis (stratum spinosum, granulosum, corneum). - The basal layer is where new cells are generated, not where they reach their mature, fully keratinized state. *Present only in basal layer* - While keratinocytes originate in the basal layer, they are the **predominant cell type throughout all layers of the epidermis**. - They represent approximately 90% of epidermal cells and are found from the stratum basale to the stratum corneum.

Q: The strongest and thickest layer of the esophagus is

Muscularis. ***Muscularis*** The **muscularis propria** (or muscularis externa) is the thickest and strongest layer in the esophagus, responsible for the **peristaltic contractions** that propel food. It consists of an inner layer of circular muscle and an outer layer of longitudinal muscle, with the coordinated action of these two layers being crucial for **swallowing** [1]. *Mucosa* The mucosa is the innermost layer [1], primarily involved in protection and some secretory functions, but it is not the thickest or strongest. It consists of non-keratinized stratified squamous epithelium, lamina propria, and muscularis mucosae. *Submucosa* The submucosa is a layer of connective tissue that contains blood vessels, lymphatics, and nerves (Meissner's plexus). While important for support and nutrient supply, it is structurally weaker and thinner than the muscularis layer. *Adventitia* The adventitia is the outermost layer of the esophagus in the neck and thorax, consisting of loose connective tissue. Its primary role is to anchor the esophagus to surrounding structures, rather than providing strength for peristalsis.

Q: Stem cells in skin involved in skin homeostasis are present in the following areas except ______

Base of apocrine glands. ***Base of apocrine glands*** - **Apocrine glands** do not typically house multipotent stem cells responsible for skin homeostasis and regeneration in the same manner as other skin adnexal structures [1] - These glands are primarily involved in secreting a specific type of sweat and have **limited regenerative capacity** from intrinsic stem cells compared to other areas - Unlike other skin appendages, apocrine glands lack the well-characterized stem cell niches that contribute to continuous skin renewal *Basal layer of interfollicular epidermis* - The basal layer contains **keratinocyte stem cells** that are crucial for continuous replenishment of epidermal layers [1] - These stem cells ensure constant turnover and repair of the skin's outermost protective barrier [1] - This is a major site of stem cells involved in skin homeostasis *Base of sebaceous glands* - Contains stem cell populations that contribute to regeneration of sebaceous glands and can differentiate to contribute to epidermal repair, especially after injury - These stem cells maintain the integrity and function of sebaceous glands, which produce sebum - Plays an active role in skin homeostasis and wound healing *Bulge of hair follicle* - The **bulge region** is a well-established niche for multipotent **hair follicle stem cells (HFSCs)** [1] - These HFSCs are responsible for cyclical regeneration of the hair follicle and can contribute to repair of the interfollicular epidermis and sebaceous glands after injury [1] - One of the most important stem cell reservoirs in the skin

Q: All of the following are true about skeletal muscle except?

The nuclei are central. The nuclei are central - Skeletal muscle fibers are **multinucleated**, but their nuclei are typically located **peripherally** (just beneath the sarcolemma), not centrally. - This peripheral placement allows the contractile proteins to occupy the majority of the cell's volume. *Have multiple nuclei* - Skeletal muscle cells develop from the fusion of multiple myoblasts, resulting in **syncytia** with numerous nuclei. - This high number of nuclei supports the large volume and metabolic demands of these long, contractile cells. *Have transverse striations* - The organized arrangement of **actin and myosin filaments** into sarcomeres creates a characteristic pattern of light (I bands) and dark (A bands) bands [2]. - These regularly repeating bands are visible as **transverse striations** under a light microscope [1]. *They are cylindrical in shape* - Individual skeletal muscle fibers are typically long and **cylindrical**, maintaining a relatively uniform diameter along their length. - This shape is well-suited for their primary function of generating force and shortening.

Q: Vitreous humor of eye contains collagen type:

Collagen II. ***Collagen II*** - Collagen II is the **predominant collagen type** found in hyaline cartilage and the **vitreous humor** of the eye, providing structural support. - In the vitreous, it forms fine fibrils that contribute to the gel-like consistency and **transparency** essential for vision. *Collagen I* - Collagen I is the most abundant collagen in the body, found in connective tissues such as **bone**, **skin**, **tendons**, and **ligaments**. - Its primary role is to provide **tensile strength** and structural integrity to these tissues. *Collagen IV* - Collagen IV is a major component of **basement membranes**, where it forms a mesh-like network providing structural support and **filtration barriers**. - It is found in the basal lamina of epithelia, kidneys, and blood vessels, but not primarily in the vitreous humor. *Collagen III* - Collagen III is typically found alongside type I collagen in **reticular fibers** in tissues like skin, blood vessels, and internal organs. - It contributes to the **elasticity** and resilience of connective tissues, but is not the main collagen of the vitreous.

Q: The connective tissue layer around each muscle fascicle is called:

Perimysium. ***Perimysium*** - This **connective tissue sheath** surrounds a bundle of muscle fibers, known as a **fascicle**. - It contains **blood vessels** and **nerves** that supply the muscle fibers within the fascicle. *Epimysium* - This is the **outermost layer of connective tissue** that surrounds the entire skeletal muscle. - It blends with the **deep fascia** and helps to separate individual muscles from surrounding tissues. *Sarcolemma* - This refers to the **plasma membrane** of a muscle fiber (muscle cell). - It plays a crucial role in transmitting the **electrical impulses** that initiate muscle contraction. *Endomysium* - This delicate layer of connective tissue surrounds and **insulates each individual muscle fiber**. - It contains **capillaries** and **nerve fibers** that supply the individual muscle cells.

Q: The distal nail matrix forms which of the following?

Ventral Portion of nail plate. ***Ventral Portion of nail plate*** The **distal nail matrix** is the primary contributor to the bulk of the **nail plate**, specifically forming its **ventral (inferior/deeper) portion**. This region is responsible for the rapid proliferation and keratinization of cells that give the nail its thickness and strength. The distal matrix accounts for approximately **80-90% of the nail plate volume**. *Dorsal Portion of nail plate* The **dorsal (superficial/top) portion of the nail plate** is predominantly formed by the **proximal nail matrix**, not the distal matrix. This part contributes to the smooth, shiny superficial layer of the nail. *Both of the options* This is incorrect because the **distal and proximal nail matrices** have distinct and separate roles in forming specific parts of the nail plate. The distal matrix forms only the ventral portion, while the proximal matrix forms the dorsal portion. *None of the options* This is incorrect as the **distal nail matrix** clearly has a specific and significant role in **nail plate formation**, specifically forming the ventral portion.

Q: Arterio-venous anastomosis is not seen in:

Kidney. ***Kidney*** - The kidney's primary function is **filtration and reabsorption**, which relies on a precise capillary network (glomerulus and peritubular capillaries) rather than direct arteriovenous shunting [1]. - Kidneys do NOT have **arteriovenous anastomoses (AVAs)** for thermoregulation like those present in acral and facial regions. - The renal circulation is specialized for maintaining glomerular filtration pressure and does not feature direct arteriovenous connections that bypass capillary beds [1]. *Finger tip* - The **fingertips** are rich in **arteriovenous anastomoses (AVAs)**, specifically **glomus bodies (glomera)**, which are crucial for thermoregulation. - These AVAs allow for rapid bypass of capillary beds, diverting blood away from the surface during cold exposure to conserve heat, or increasing flow during warm conditions for heat dissipation. *Ear lobule* - The **ear lobule** contains abundant **arteriovenous anastomoses** that play an important role in **thermoregulation**. - These AVAs help regulate heat loss from the body by controlling blood flow through the highly vascularized ear tissue. *Tip of Nose* - The **tip of the nose** is another classic location where **arteriovenous anastomoses (AVAs)** are abundant, serving a critical role in **thermoregulation**. - These AVAs help in rapid heat dissipation or conservation by controlling blood flow through the capillary beds of the nasal tip.

Q: Prefilaggrin is found in which layer of epidermis?

Stratum granulosum. ***Stratum granulosum*** - **Prefilaggrin** is synthesized in the **stratum granulosum** as a large, insoluble protein that is stored in keratohyalin granules [1]. - It later undergoes proteolytic cleavage to form **filaggrin**, which is crucial for keratin filament aggregation and skin barrier function in the upper layers [1]. *Stratum basale* - This layer contains **basal cells** responsible for epidermal regeneration and is where keratinocyte proliferation occurs [1]. - It does not contain prefilaggrin, as this protein is synthesized in more differentiated keratinocytes. *Stratum spinosum* - This layer is characterized by abundant **desmosomes** (spinous processes) providing structural integrity. - While keratinization begins here, **prefilaggrin synthesis** primarily occurs in the stratum granulosum. *Stratum corneum* - This outermost layer consists of flattened, dead keratinocytes filled with **keratin** and **filaggrin**, a breakdown product of prefilaggrin [1]. - **Prefilaggrin itself is not found here**; it has already been processed into filaggrin by the time cells reach this layer.

Question 1

Which of the following layers of epidermis is known as "prickle layer"?

Accepted Answer

Stratum spinosum

Answer

Stratum basale

Answer

Stratum granulosum

Answer

Stratum corneum

Question 2

Which of the following is true about keratinocytes?

Accepted Answer

Ectoderm derived cell

Answer

Differentiate in basal layer

Answer

Mature in basal layer

Answer

Present only in basal layer

Question 3

The strongest and thickest layer of the esophagus is

Accepted Answer

Muscularis

Answer

Mucosa

Answer

Submucosa

Answer

Adventitia

Question 4

Stem cells in skin involved in skin homeostasis are present in the following areas except ______

Accepted Answer

Base of apocrine glands

Answer

Basal layer of interfollicular epidermis

Answer

Base of sebaceous glands

Answer

Bulge of Hair follicle

Question 5

All of the following are true about skeletal muscle except?

Accepted Answer

The nuclei are central

Answer

Have multiple nuclei

Answer

Have transverse striations

Answer

They are cylindrical in shape

Question 6

Vitreous humor of eye contains collagen type:

Accepted Answer

Collagen II

Answer

Collagen I

Answer

Collagen IV

Answer

Collagen III

Question 7

The connective tissue layer around each muscle fascicle is called:

Accepted Answer

Perimysium

Answer

Epimysium

Answer

Sarcolemma

Answer

Endomysium

Question 8

The distal nail matrix forms which of the following?

Accepted Answer

Ventral Portion of nail plate

Answer

Dorsal Portion of nail plate

Answer

Both of the options

Answer

None of the options

Question 9

Arterio-venous anastomosis is not seen in:

Accepted Answer

Kidney

Answer

Finger tip

Answer

Ear lobule

Answer

Tip of Nose

Question 10

Prefilaggrin is found in which layer of epidermis?

Accepted Answer

Stratum granulosum

Answer

Stratum basale

Answer

Stratum spinosum

Answer

Stratum corneum

Histology — MCQs

Histology — MCQs

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