Histology Practice Questions

Q: All of the following are coverings of a mature Graafian follicle, except?

Germinal cells. ### Explanation The **Graafian follicle** is the mature, pre-ovulatory stage of follicular development. To identify its coverings, one must understand the histological layers that surround the oocyte as it matures within the ovary. **Why "Germinal cells" is the correct answer:** The term "Germinal cells" (or germinal epithelium) refers to the **simple cuboidal epithelium** that covers the **outer surface of the ovary** [1]. It is not a component or a covering of the individual Graafian follicle itself. Instead, it is a modified part of the peritoneum that lines the ovary. **Analysis of incorrect options:** * **Theca externa:** This is the outermost layer of the follicle, composed of fibrous connective tissue and smooth muscle cells. It helps in the contraction required for ovulation. * **Theca interna:** The vascularized inner layer of the theca, responsible for secreting androgens (androstenedione) which are later converted to estrogen [3]. * **Granulosa cells:** These are the stratified cuboidal cells lining the follicle. They possess aromatase enzymes to convert thecal androgens into estrogens and form the *cumulus oophorus* and *corona radiata* around the oocyte. **High-Yield Clinical Pearls for NEET-PG:** * **Theca Interna:** Site of LH action (produces androgens). * **Granulosa Cells:** Site of FSH action (converts androgens to estrogens). * **Antrum:** The fluid-filled cavity characteristic of secondary and Graafian follicles, containing *Liquor folliculi*. * **Stigma:** The point on the ovarian surface where the Graafian follicle ruptures during ovulation. * **Germinal Epithelium:** Despite its name, it does *not* give rise to germ cells (oocytes); germ cells migrate from the yolk sac endoderm [2]. Most ovarian cancers (70%) arise from this epithelial layer.

Q: The caries of the enamel surface leads to accentuation of which of the following?

Incremental lines of Retzius. **Explanation:** **Incremental lines of Retzius** are rhythmic growth marks representing the weekly mineralization pattern of enamel. In a healthy tooth, these lines are visible in ground sections as brownish bands. When dental caries occurs, the acid produced by bacteria causes **demineralization** along these pre-existing structural pathways. This loss of mineral content increases the porosity and visibility of these lines under microscopic examination, a phenomenon known as **accentuation**. **Analysis of Incorrect Options:** * **Perikymata:** These are the external surface manifestations of the Striae of Retzius. They appear as shallow grooves on the enamel surface. While related, they are surface features rather than the internal structural lines accentuated by the subsurface demineralization of caries. * **Imbrication lines of Pickerill:** These are the elevations (ridges) found between perikymata. Like perikymata, they are surface topographical features, not the internal histological lines affected by the progression of decay. * **Wickham’s striae:** This is a clinical term used in dermatology/oral pathology to describe the characteristic white, lace-like patterns seen in **Lichen Planus**. It is unrelated to enamel histology or dental caries. **High-Yield Clinical Pearls for NEET-PG:** * **Neonatal Line:** This is an exceptionally enlarged Stria of Retzius found in deciduous teeth and first permanent molars, marking the physiological stress of birth. * **Hunter-Schreger Bands:** These are an optical phenomenon (not growth lines) caused by the change in direction of enamel rods. * **Enamel Lamellae:** These are leaf-like defects that span the entire thickness of enamel and can act as pathways for dental caries to reach the dentin.

Q: Fibrocartilage is found in which of the following locations?

Intervertebral disc. **Explanation:** Cartilage is classified into three types based on the composition of its matrix: Hyaline, Elastic, and Fibrocartilage. **1. Why the Correct Answer is Right:** **Intervertebral discs (Option C)** are composed of **Fibrocartilage**. This tissue is characterized by dense bundles of **Type I collagen** fibers arranged in a parallel fashion, providing high tensile strength and the ability to withstand heavy pressure [1]. It lacks a perichondrium. Other classic locations include the pubic symphysis, glenoid labrum, acetabular labrum, and the articular discs of the temporomandibular joint (TMJ). **2. Why the Incorrect Options are Wrong:** * **Costal cartilage (Option A) and Nasal septum (Option B):** These are examples of **Hyaline cartilage**, the most common type in the body [2]. It contains Type II collagen and has a "glassy" appearance [2]. Other sites include the articular surfaces of long joints, tracheal rings, and the embryonic skeleton. * **Auditory tube (Option D):** This contains **Elastic cartilage**. It is characterized by a dense network of elastic fibers, providing flexibility and the ability to recoil. Other sites include the Pinna (auricle), External Auditory Meatus, and the Epiglottis (the "3 Es"). **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Collagen Types:** Remember that Hyaline and Elastic cartilage contain **Type II** collagen [2], whereas Fibrocartilage is unique for containing **Type I** collagen [1]. * **Perichondrium:** Fibrocartilage and Articular (hyaline) cartilage are the two types that **lack a perichondrium**. * **Calcification:** Hyaline cartilage calcifies with age; Fibrocartilage can also calcify, but Elastic cartilage **never** calcifies. * **Mnemonics:** For Elastic cartilage, remember the **"P-E-E-E"** rule: Pinna, Epiglottis, Eustachian (Auditory) tube, and External auditory meatus.

Q: Which of the following statements about the nucleolus is false?

Contains DNA. The nucleolus is a dense, non-membrane-bound structure within the nucleus, primarily responsible for ribosome biogenesis. **Why Option A is the Correct Answer (The "False" Statement):** While the nucleolus is associated with specific regions of chromosomes (Nucleolar Organizer Regions), it is primarily composed of **RNA and proteins**. In the context of standard histology and cell biology questions, the nucleolus is defined as a site of RNA synthesis and processing rather than a storage site for genomic DNA. While chromatin (DNA) loops into the nucleolus to provide the template for rRNA, the nucleolus itself is classically described as an **RNA-rich organelle**, making the statement "Contains DNA" the least accurate/false description among the choices provided in a competitive exam context. **Analysis of Other Options:** * **Option B (Contains RNA):** This is true. The nucleolus is the site of transcription for **rRNA** (ribosomal RNA), which makes up the bulk of its structure. * **Option C (Contains genes for ribosomes):** This is true. It contains the **Nucleolar Organizer Regions (NORs)** located on the secondary constrictions of acrocentric chromosomes (13, 14, 15, 21, and 22), which carry the genes for 5.8S, 18S, and 28S rRNA. * **Option D (Has no limiting membrane):** This is true. The nucleolus is a **biomolecular condensate** formed via liquid-liquid phase separation; it lacks a phospholipid bilayer. **NEET-PG High-Yield Pearls:** * **Acrocentric Chromosomes:** Remember the numbers **13, 14, 15, 21, 22**—these contain the NORs that form the nucleolus. * **Staining:** The nucleolus is highly **basophilic** due to the high concentration of RNA. * **Clinical Significance:** Large, prominent nucleoli are a hallmark of **malignant cells** and cells actively engaged in high protein synthesis (e.g., plasma cells, neurons).

Q: What is the epithelial lining of the conjunctiva?

Stratified squamous non-keratinized. **Explanation:** The conjunctiva is a thin, translucent mucous membrane that covers the anterior surface of the eyeball (bulbar conjunctiva) and the inner surface of the eyelids (palpebral conjunctiva) [1]. **Why Option D is Correct:** The primary function of the conjunctiva is to protect the eye and maintain the tear film. To withstand the constant friction of blinking while remaining moist, it is lined by **stratified squamous non-keratinized epithelium**. However, it is important to note that the histology varies by region: the palpebral part is more columnar, while the bulbar and limbal areas are predominantly stratified squamous [1]. For exam purposes, it is classified as a non-keratinized stratified epithelium. **Analysis of Incorrect Options:** * **A. Squamous keratinized:** This is found in the skin (epidermis). Keratin provides a waterproof, tough barrier. If the conjunctiva becomes keratinized (as seen in severe Vitamin A deficiency), it leads to Bitot’s spots and blindness. * **B. Pseudo-stratified:** This is characteristic of the respiratory tract (ciliated) or the male reproductive tract (with stereocilia). * **C. Cuboidal:** Simple cuboidal epithelium is typically found in glandular ducts or the thyroid follicles, not in areas requiring protective lining against friction. **High-Yield NEET-PG Pearls:** 1. **Goblet Cells:** The conjunctiva contains unicellular mucous glands called Goblet cells, which secrete the **mucin layer** of the tear film [1]. 2. **Vitamin A Deficiency:** Leads to squamous metaplasia (transformation from non-keratinized to keratinized), resulting in **Xerophthalmia**. 3. **Limbus:** The junction between the cornea and sclera where the conjunctival epithelium becomes continuous with the corneal epithelium [2].

Q: Claudius cells are seen in which of the following structures?

Organ of Corti. **Explanation:** **Claudius cells** are specialized supporting cells found in the **Organ of Corti** within the cochlea of the inner ear. They are located on the floor of the cochlear duct (scala media), specifically lateral to the Hensen cells, extending from the outer tunnel to the spiral prominence [1]. These cells play a crucial role in maintaining the ionic composition of the endolymph and providing structural support to the sensory hair cells [1]. **Analysis of Options:** * **Option B (Correct):** Claudius cells are cuboidal cells that form part of the supporting framework of the **Organ of Corti** [1]. They are involved in the transport of ions and fluid, essential for the auditory transduction process. * **Option A:** The **Canal of Schlemm** is a vascular structure in the eye responsible for draining aqueous humor. It is lined by endothelial cells, not Claudius cells. * **Option C:** The **Parathyroid gland** parenchyma consists primarily of Chief cells (which secrete PTH) and Oxyphil cells. * **Option D:** **Alveoli** are lined by Type I pneumocytes (gas exchange) and Type II pneumocytes (surfactant production), along with alveolar macrophages (dust cells). **High-Yield Facts for NEET-PG:** * **Supporting cells of the Organ of Corti:** These include Pillar cells, Deiters' cells (outer phalangeal cells), Hensen cells, and Claudius cells [1]. * **Böttcher cells:** These are small cells found specifically in the basal turn of the cochlea, located underneath the Claudius cells. * **Endolymph vs. Perilymph:** Remember that the Organ of Corti is bathed in endolymph (high $K^+$, low $Na^+$), and the metabolic activity of supporting cells like Claudius cells is vital for maintaining this gradient [1].

Q: Which type of bone does not contain Haversian canals?

Spongy bone. The fundamental unit of bone organization is the **Osteon (Haversian System)**. The presence or absence of Haversian canals depends on the density and vascular arrangement of the bone tissue. [1] **Why Spongy Bone is the Correct Answer:** Spongy bone (also known as cancellous or trabecular bone) does not contain Haversian canals. Instead, it is composed of a honeycomb-like network of slender spicules called **trabeculae**. [1] Because trabeculae are thin and surrounded by marrow spaces rich in blood vessels, the osteocytes receive nutrients via diffusion through canaliculi opening directly onto the surface. Therefore, a centralized canal system (Haversian canal) is structurally unnecessary. **Analysis of Incorrect Options:** * **Compact Bone & Cortical Bone (Options A & D):** These terms are often used interchangeably. Compact bone is dense and forms the outer shell of bones. [1] Because of its density, nutrients cannot reach deep-seated osteocytes by simple diffusion. It requires a complex system of **Haversian canals** (longitudinal) and **Volkmann’s canals** (transverse) to house blood vessels and nerves. * **Diaphyseal Bone (Option B):** The diaphysis is the shaft of a long bone, which is primarily composed of thick compact bone to provide structural strength. Consequently, it contains numerous Haversian systems. **High-Yield Clinical Pearls for NEET-PG:** * **Haversian Canals:** Contain blood vessels, nerves, and lymphatics; they run parallel to the long axis of the bone. * **Volkmann’s Canals:** Connect adjacent Haversian canals to each other and to the periosteum; they run perpendicular to the long axis. * **Interstitial Lamellae:** These are remnants of old Haversian systems found between intact osteons, a sign of continuous bone remodeling. * **Primary site of Hematopoiesis:** Occurs in the red marrow found within the gaps of **spongy bone**, particularly in the epiphysis of long bones and flat bones.

Q: Which is the commonest type of cartilage to ossify?

Hyaline. **Explanation:** **1. Why Hyaline Cartilage is the Correct Answer:** Hyaline cartilage is the most abundant type of cartilage in the human body and serves as the primary precursor for the skeletal system [1]. The majority of the skeleton is formed through **endochondral ossification**, a process where a hyaline cartilage model is gradually replaced by bone [2]. Furthermore, hyaline cartilage has a natural tendency to calcify and ossify with age, particularly in the costal cartilages and the laryngeal skeleton (except the epiglottis). Its matrix is rich in Type II collagen and lacks the dense elastic or thick fibrous bundles that inhibit mineralization in other types [1]. **2. Why the Other Options are Incorrect:** * **Elastic Cartilage:** Contains a dense network of elastic fibers. It is specifically designed for flexibility and resilience. It **never ossifies or calcifies**, even with advancing age (e.g., pinna of the ear, epiglottis). * **Fibrous Cartilage (Fibrocartilage):** Contains thick bundles of Type I collagen. It acts as a shock absorber in high-stress areas (e.g., intervertebral discs, pubic symphysis). While it may occasionally undergo pathological calcification, it does not routinely ossify as a physiological process. * **Fibroelastic:** This is a hybrid description and not a primary classification of cartilage in this context. **3. Clinical Pearls & High-Yield Facts:** * **Articular Cartilage:** A type of hyaline cartilage that covers joint surfaces; it is unique because it **does not have a perichondrium** and does not normally ossify (to maintain joint mobility) [1]. * **Laryngeal Cartilages:** The thyroid, cricoid, and arytenoid cartilages are hyaline and often appear radiopaque on X-rays in older adults due to ossification. * **Growth Plate:** The epiphyseal plate is composed of hyaline cartilage; its ossification marks the end of longitudinal bone growth [2].

Question 1

All of the following are coverings of a mature Graafian follicle, except?

Accepted Answer

Germinal cells

Answer

Theca externa

Answer

Theca interna

Answer

Granulosa cells

Question 2

The caries of the enamel surface leads to accentuation of which of the following?

Accepted Answer

Incremental lines of Retzius

Answer

Perikymata

Answer

Imbrication lines of Pickerill

Answer

Wickham's striae

Question 3

Fibrocartilage is found in which of the following locations?

Accepted Answer

Intervertebral disc

Answer

Costal cartilage

Answer

Nasal septum

Answer

Auditory tube

Question 4

Which of the following statements about the nucleolus is false?

Accepted Answer

Contains DNA

Answer

Contains RNA

Answer

Contains genes for ribosomes and ribosomal RNA needed in protein synthesis

Answer

Has no limiting membrane

Question 5

What is the epithelial lining of the conjunctiva?

Accepted Answer

Stratified squamous non-keratinized

Answer

Squamous keratinized

Answer

Pseudo-stratified

Answer

Cuboidal

Question 6

Claudius cells are seen in which of the following structures?

Accepted Answer

Organ of Corti

Answer

Canal of Schlemm

Answer

Parenchyma of parathyroid gland

Answer

Alveoli

Question 7

The mammary gland is a modified form of which type of gland?

Accepted Answer

Apocrine sweat gland

Answer

Merocrine gland

Answer

Sebaceous gland

Answer

Mucous gland

Question 8

Which type of bone does not contain Haversian canals?

Accepted Answer

Spongy bone

Answer

Compact bone

Answer

Diaphyseal bone

Answer

Cortical bone

Question 9

Which is the commonest type of cartilage to ossify?

Accepted Answer

Hyaline

Answer

Elastic

Answer

Fibrous

Answer

Fibroelastic

Question 10

What is true about hyaline cartilage?

Accepted Answer

Hyaline cartilage covers the articular surface of synovial joints.

Answer

Hyaline cartilage is present in all synovial joints.

Answer

Articular cartilage may undergo ossification with aging.

Answer

Articular cartilage limits the mobility of the joint.

Histology — MCQs

Histology — MCQs

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