MLT GlobeHistopathology: Cells, tissues & basic histology – page 4
88 Histopathology MCQs on Cells, tissues & basic histology with answers and explanations.
The auricle (pinna) of the external ear is supported by which cartilage?
Elastic cartilage in the pinna, epiglottis and external auditory canal gives flexibility. Note that the middle ear ossicles are bone, not cartilage.
Which structure belongs to the central nervous system?
The CNS consists of the brain and spinal cord. Peripheral nerves, plexuses and ganglia belong to the peripheral nervous system.
The outer boundary of a cell, visible by electron microscopy as a trilaminar structure, is the:
The plasmalemma is a lipid bilayer forming the cell boundary. The glycocalyx is a carbohydrate coat on its outer surface; cristae are mitochondrial folds.
In the gastric glands, pepsinogen is secreted mainly by:
Chief cells at the base of fundic glands secrete pepsinogen. Parietal cells secrete HCl and intrinsic factor; mucous neck cells secrete mucus.
Osteocytes contact each other through fine channels in the bone matrix called:
Canaliculi carry osteocyte processes and allow exchange with the Haversian canal. Volkmann's canals carry vessels; Sharpey's fibres anchor periosteum.
The most widespread cartilage type in the body, found in articular surfaces, costal cartilages and the respiratory tract, is:
Hyaline cartilage is the most abundant, with a glassy matrix of type II collagen. Elastic and fibrocartilage occur at more limited sites.
The dense connective tissue layer that surrounds most hyaline cartilage and contains chondrogenic cells is the:
The perichondrium supports appositional cartilage growth. Articular cartilage lacks a perichondrium; periosteum covers bone.
Skeletal muscle fibres rich in mitochondria and myoglobin, adapted for sustained aerobic activity, are:
Type I fibres rely on oxidative metabolism and so have many mitochondria and much myoglobin. Type IIb fibres are glycolytic with fewer mitochondria.
The antigen-presenting dendritic cells of the epidermis, containing Birbeck granules, are:
Langerhans cells are bone-marrow-derived dendritic cells in the stratum spinosum. Kupffer cells are liver macrophages; Merkel cells are mechanoreceptor-associated.
Nissl bodies seen in neuronal cytoplasm are composed of:
Nissl bodies are stacks of rough ER and free ribosomes; their RNA makes them basophilic. They are absent from the axon hillock.
Which of the following is an organelle rather than a cytoplasmic inclusion?
Inclusions are non-living stored or accumulated materials such as glycogen, lipid and pigment. Mitochondria are metabolically active, membrane-bound organelles.
A longitudinal section of tendon shows:
Tendon is dense regular connective tissue of type I collagen, with elongated fibroblasts (tenocytes) between bundles. Elastic ligaments are the exception.
In an H&E section, the loosely packed, transcriptionally active chromatin that appears pale is:
Euchromatin is dispersed and stains only faintly with haematoxylin. Heterochromatin, including the Barr body, is condensed and stains darkly.
Fine, unbundled fibres that form the supporting mesh of lymph nodes, spleen and bone marrow are made of:
Reticular fibres are type III collagen forming delicate networks that support immune cells; type I forms thick bundles, type IV basement membranes.
Connexin proteins form the channels of which cell junction?
Six connexins form a connexon; paired connexons link cytoplasms at gap junctions. Claudins and occludin build tight junctions.
Flattened, inactive osteoblasts covering quiescent bone surfaces are called:
Bone lining cells are resting osteoblasts that can reactivate; osteocytes are trapped in lacunae within bone.
Motor neurons and interneurons are multipolar. Which neuron type is typically pseudounipolar instead?
Dorsal root ganglion sensory neurons have one process that splits into peripheral and central branches; the others are multipolar.
An exocrine gland whose secretory unit is flask-shaped is described as:
Rounded, flask-like secretory units are alveolar or acinar; simple and compound describe the duct, not the secretory shape.
Ceruminous glands of the external ear canal are modified:
Ceruminous glands are modified apocrine glands that help form earwax together with sebaceous secretions.
Classification of muscle fibers into type I (red, slow-twitch) and type II (white, fast-twitch) applies to which muscle?
Fiber typing by myoglobin content, ATPase activity and contraction speed is used for skeletal muscle, e.g. in muscle biopsy histochemistry. Smooth muscle is not divided into red and white fibers.