Anatomy
7 questionsSertoli cells are derived from -
Which type of glial cell is derived from mesodermal origin?
Trigone of bladder is derived from?
Spleniculi are most commonly found in which of the following locations?
What structure passes through the quadrangular space?
Seminal colliculus is present in ?
Which of the following is not a derivative of foregut?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 221: Sertoli cells are derived from -
- A. Genital swelling
- B. Coelomic epithelium (Correct Answer)
- C. Primordial germ cells
- D. Germinal epithelium
Explanation: Sertoli cells are derived from the **coelomic epithelium** (surface epithelium) of the urogenital ridge during gonadal development. - The coelomic epithelium proliferates to form the **primitive sex cords** (medullary cords in males), and cells within these cords differentiate into Sertoli cells. - These cells are essential for **spermatogenesis**, providing structural support and nutrition to developing germ cells, and producing **anti-Müllerian hormone (AMH)** which causes regression of Müllerian ducts in male development [1]. *Germinal epithelium* - This is an **outdated term** previously used for the surface epithelium of the gonad, based on the misconception that it gave rise to germ cells. - Modern embryology uses the term **coelomic epithelium** or surface epithelium instead. - While historically used, this terminology is no longer preferred in current medical literature. *Genital swelling* - **Genital swellings** (labioscrotal swellings) are external mesodermal structures that develop into the **scrotum** in males or **labia majora** in females. - These are external genitalia components and are not the source of internal testicular cells like Sertoli cells. *Primordial germ cells* - **Primordial germ cells (PGCs)** originate from the epiblast, migrate via the hindgut to the developing gonads, and differentiate into **spermatogonia** (males) or **oogonia** (females) [1]. - They form the **germ cell lineage** (gametes), not somatic support cells like Sertoli cells, which are of coelomic epithelial origin.
Question 222: Which type of glial cell is derived from mesodermal origin?
- A. Macroglial cells
- B. Microglial cells (Correct Answer)
- C. Oligodendrocytes
- D. Ependymal cells
Explanation: ***Microglial cells*** - **Microglial cells** are unique among glial cells as they originate from **mesoderm**, specifically from **monocyte/macrophage precursors** in the bone marrow [1]. - They function as the **immune cells of the central nervous system (CNS)**, scavenging for plaques, damaged neurons, and infectious agents [1]. *Macroglial cells* - This is a broad category that includes **astrocytes, oligodendrocytes, and ependymal cells**, all of which are derived from **neuroectoderm**, not mesoderm [1]. - They perform various supportive roles but are distinct in origin from microglial cells [1]. *Oligodendrocytes* - **Oligodendrocytes** are derived from **neuroectoderm** and are responsible for forming the **myelin sheath** around axons in the CNS [2]. - Myelination is crucial for rapid and efficient nerve impulse conduction. *Ependymal cells* - **Ependymal cells** are derived from **neuroectoderm** and line the **ventricles of the brain** and the **central canal of the spinal cord**. - They play a role in the production and circulation of **cerebrospinal fluid (CSF)**.
Question 223: Trigone of bladder is derived from?
- A. Mesonephric duct (Correct Answer)
- B. Paramesonephric duct
- C. Absorbed anal membrane
- D. Mullerian duct
Explanation: The trigone of the bladder is formed from the caudal ends of the **mesonephric ducts**, which are absorbed into the primitive bladder wall [1]. This mesenchymal origin explains why the trigone has a smooth lining [1] and is less prone to infection compared to the rest of the bladder. *Paramesonephric duct* - The **paramesonephric ducts** (Müllerian ducts) are involved in forming the female reproductive organs, specifically the fallopian tubes, uterus [2], and upper vagina. - They do not contribute to the formation of the urinary bladder or its trigone. *Absorbed anal membrane* - The **anal membrane** separates the endoderm-derived hindgut from the ectoderm-derived anal pit. - Its absorption is relevant to the development of the anus, not the urinary bladder. *Mullerian duct* - The **Müllerian ducts** are synonymous with the paramesonephric ducts and are primarily involved in the development of the female reproductive tract [2]. - They play no role in the development of the urinary bladder or its trigone.
Question 224: Spleniculi are most commonly found in which of the following locations?
- A. Colon
- B. Liver
- C. Lungs
- D. Hilum of the spleen (Correct Answer)
Explanation: No relevant citations could be added to the explanation as the provided text passages did not contain information regarding spleniculi (accessory spleens), their location, or their embryology. ***Hilum of the spleen*** - **Spleniculi** (accessory spleens) are most commonly found at the **hilum of the spleen**, accounting for approximately **75% of cases**. - During **embryonic development**, the spleen forms from mesenchymal tissue in the dorsal mesogastrium, and small fragments of splenic tissue can separate and persist as accessory spleens. - The **splenic hilum** is the most frequent location due to the close proximity during development, followed by the gastrosplenic ligament, tail of pancreas, and greater omentum. - Accessory spleens are found in **10-30% of the population** and are clinically significant in conditions requiring complete splenectomy (e.g., ITP, hereditary spherocytosis). *Colon* - The colon is part of the **gastrointestinal tract** with a completely different embryological origin (endodermal). - Splenic tissue development occurs in the **dorsal mesogastrium** (mesodermal origin), making the colon an anatomically and embryologically implausible location for spleniculi. *Liver* - The liver develops from the **ventral foregut endoderm** and is anatomically distant from the spleen's developmental region. - **Splenosis** (traumatic implantation) could theoretically occur, but congenital spleniculi in the liver are exceptionally rare and not a recognized common location. *Lungs* - The lungs are part of the **respiratory system**, developing from the foregut endoderm in the thoracic cavity. - There is no embryological connection between lung and splenic tissue development, making this an impossible location for congenital accessory spleens.
Question 225: What structure passes through the quadrangular space?
- A. Axillary nerve (Correct Answer)
- B. Radial nerve
- C. Median nerve
- D. Brachial Artery
Explanation: Axillary nerve - The axillary nerve and the posterior circumflex humeral artery are the primary structures that pass through the quadrangular space. - Compression or injury within this space can lead to deficits in the axillary nerve's distribution, affecting the deltoid and teres minor muscles. *Radial nerve* - The radial nerve passes through the triangular interval, not the quadrangular space. - It supplies the triceps muscle and all muscles in the posterior compartment of the forearm. *Median nerve* - The median nerve travels through the cubital fossa and then down the anterior forearm, supplying most of the forearm flexors and some hand muscles. - It does not pass through any of the posterior axillary spaces. *Brachial Artery* - The brachial artery is the main arterial supply to the arm and runs anteriorly in the arm, deep to the biceps brachii muscle. - It does not pass through the quadrangular space; rather, the posterior circumflex humeral artery (a branch of the axillary artery) traverses this space.
Question 226: Seminal colliculus is present in ?
- A. Testis
- B. Prostate
- C. Urethra (Correct Answer)
- D. Scrotum
Explanation: ***Correct: Urethra*** - The **seminal colliculus** (also known as the **verumontanum**) is a prominent ridge located on the posterior wall of the **prostatic urethra** - It contains the openings of the **ejaculatory ducts** and the **prostatic utricle** - This is a key anatomical landmark in the male urethra during endoscopic procedures *Incorrect: Prostate* - While the seminal colliculus is located within the portion of the urethra that passes through the prostate (prostatic urethra), it is not a structure *of* the prostate gland itself - The prostate is a gland that surrounds the urethra and contributes to seminal fluid - The seminal colliculus is an intraluminal urethral structure, not prostatic tissue *Incorrect: Testis* - The testis is the primary male reproductive organ responsible for **spermatogenesis** and hormone synthesis (testosterone) - It does not contain the seminal colliculus, which is located in the pelvic urethra *Incorrect: Scrotum* - The scrotum is an external dermal sac that houses the testes, epididymis, and lower spermatic cords - It provides temperature regulation for spermatogenesis - The seminal colliculus is an internal pelvic structure, not present in the scrotum
Question 227: Which of the following is not a derivative of foregut?
- A. Cecum (Correct Answer)
- B. Liver
- C. Pancreas
- D. First part of the duodenum
Explanation: ***Cecum*** - The **cecum** and the entire large intestine (except the distal third of the transverse colon) are derivatives of the **midgut** [1]. - The midgut is supplied by the **superior mesenteric artery**, differentiating it developmentally from the foregut. *First part of the duodenum* - The **first part of the duodenum** (from the pylorus to the major duodenal papilla) is derived from the **foregut**. - This section receives its blood supply from branches of the **celiac trunk**, consistent with its foregut origin. *Liver* - The **liver** develops as a budding from the distal foregut and is therefore a **foregut derivative** [2]. - It plays a crucial role in metabolism and detoxification, consistent with its early development from this segment. *Pancreas* - The **pancreas** develops from dorsal and ventral buds of the distal foregut, making it a **foregut derivative**. - Both its exocrine and endocrine functions are vital for digestion and glucose homeostasis.
Pharmacology
2 questionsWhich of the following oral antidiabetic drugs is an insulin secretagogue?
At which receptor is the primary action of antipsychotic medications required?
NEET-PG 2015 - Pharmacology NEET-PG Practice Questions and MCQs
Question 221: Which of the following oral antidiabetic drugs is an insulin secretagogue?
- A. Metformin
- B. Pioglitazone
- C. Nateglinide (Correct Answer)
- D. Acarbose
Explanation: **Nateglinide** - **Nateglinide** is a **meglitinide**, which is a type of **insulin secretagogue**. - It stimulates **insulin release** from pancreatic beta cells by blocking ATP-sensitive potassium channels. *Metformin* - **Metformin** is a **biguanide** that primarily works by **decreasing hepatic glucose production** and increasing insulin sensitivity in peripheral tissues. - It does not directly stimulate insulin secretion. *Pioglitazone* - **Pioglitazone** is a **thiazolidinedione** (TZD) that improves insulin sensitivity by activating **PPAR-gamma receptors**. - It does not directly affect insulin secretion but rather enhances the body's response to existing insulin. *Acarbose* - **Acarbose** is an **alpha-glucosidase inhibitor** that delays the digestion and absorption of carbohydrates in the small intestine. - This reduces postprandial glucose excursions and does not directly stimulate insulin secretion.
Question 222: At which receptor is the primary action of antipsychotic medications required?
- A. M, muscarinic
- B. 5HT4 serotonergic
- C. D1 dopaminergic
- D. D2 dopaminergic (Correct Answer)
Explanation: ***D2 dopaminergic*** - The **antipsychotic effects** of typical (first-generation) antipsychotics are primarily mediated through **D2 receptor blockade** [1]. - Blocking D2 receptors in the **mesolimbic pathway** helps reduce positive symptoms of psychosis like hallucinations and delusions [2]. *M, muscarinic* - **Muscarinic receptor blockade** is a common adverse effect of some antipsychotics, leading to anticholinergic side effects such as **dry mouth** and **blurred vision**, rather than their primary therapeutic action. - This action does not directly contribute to the antipsychotic effect. *D1 dopaminergic* - While D1 receptors are involved in dopamine signaling, they are **not the primary target** for the antipsychotic action of most drugs [1]. - Some atypical antipsychotics may affect D1 receptors, but it's secondary to their D2 antagonism and serotonin modulation. *5HT4 serotonergic* - **Serotonin receptors (5HT)**, particularly 5HT2A, are important targets for atypical (second-generation) antipsychotics. - However, 5HT4 receptors are **not a primary target** for the antipsychotic effects, and 5HT2A blockade modulates dopamine release, which is still connected to the D2 hypothesis.
Surgery
1 questionsWhich of the following structures does NOT pass through Calot's triangle?
NEET-PG 2015 - Surgery NEET-PG Practice Questions and MCQs
Question 221: Which of the following structures does NOT pass through Calot's triangle?
- A. Right hepatic artery
- B. Lymph node of Lund
- C. Portal vein (Correct Answer)
- D. Cystic artery
Explanation: ***Portal vein*** - The **portal vein** is a major vessel that carries venous blood from the gastrointestinal tract and spleen to the liver; it is located within the **porta hepatis** and does not pass through Calot's triangle. - Its position is medial and posterior to the structures within Calot's triangle, making it an unlikely structure to be inadvertently ligated during cholecystectomy. *Cystic artery* - The **cystic artery** is a consistent structure found within Calot's triangle, typically arising from the **right hepatic artery**. - Its presence in the triangle makes it a primary target for ligation during **cholecystectomy**. *Right hepatic artery* - The **right hepatic artery** typically runs **superior to Calot's triangle** and gives off the cystic artery which enters the triangle. - While the right hepatic artery itself does not routinely pass through the triangle, anatomical variations may bring it into close proximity, and it can be at risk of injury during dissection if the critical view of safety is not established. *Lymph node of Lund* - The **lymph node of Lund**, also known as the cystic lymph node, is a key landmark located within Calot's triangle. - Its presence is important for identifying the boundaries of the triangle and assessing for inflammation or malignancy related to the gallbladder.