QUIZ – Nervous tissue: MCQ’s – X type (true or false) 1. The histological characteristics of multipolar neurons include: a. A heterochromatic nucleus F b. A prominent nucleolus T c. Sparse rough endoplasmic reticulum F d. A large cell body T e. Abundant Nissl bodies T 2. In the Peripheral Nervous System, Schwann cells: a. Produce myelin T b. Envelop unmyelinated axons T c. Produce collagen fibres T d. Conduct impulses F e. Are interneurons F 3. With regard to the perineurium : a. It surrounds a nerve fascicle T b. Perineural cells contribute to the blood-nerve barrier T c. It is a typical dense connective tissue F d. It is continuous with the endomysium F e. It contains many lymphocytes F 4. With regard to the dorsal root ganglia of spinal nerves: a. Neuronal cell bodies are surrounded by satellite cells T b. They consist of efferent neurons F c. They contain afferent nerve fibres T d. They are found within the CNS F e. They consist of pseudounipolar neurons T 5. With regard to the node of Ranvier: a. It insulates the axon F b. It represents the junction between adjacent Schwann cells T c. It is required for saltatory conduction T d. It allows for an increase in the rate of impulse transmission T e. It is present in unmyelinated axons F Short Answer Questions Describe the histological- and ultrastructure and function of an anterior horn cell. (5 marks) • Multipolar neuron with one axon and multiple dendrites (½) - motor neuron convey impulses from CNS to effector cells (½) • Large vesicular cell body with pale-staining, euchromatic nucleus (½) indicating active transcription (½) • Prominent nucleolus(½) indicating rRNA synthesis (½) • Perinuclear cytoplasm contains: o Abundant RER (Nissl substance) (½) and free ribosomes (½) – indicating protein synthesis (½) o Prominent Golgi apparatus (½) and abundant mitochondria (½) indicate high anabolic activity (½) • Axon hillock devoid of Nissl substance (½) – initial segment below at which an action potential is generated (½) Describe the histological structure and function of the connective tissue sheaths found in association with a peripheral nerve e.g. the median nerve. (6 marks) • Endoneurium (½) o Loose connective tissue (½) surrounds each individual nerve fibre (½) o Composed of collagen fibres, occasional fibroblasts, macrophages and mast cells may be present (½) • Perineurium (½) o Specialized connective tissue (½) that surrounds a fascicle (bundles) of nerve fibres (½) o Contributes to formation of the blood-nerve barrier (½) o Composed of collagen fibres, occasional fibroblasts, macrophages and mast cells may be present (½) • Epineurium (½) o Dense irregular connective tissue(½) that surrounds the fascicles and forms the outermost layer of CT(½) o BVs travel penetrate the epineurium(½), branching into the perineurium (½) Spotters 1) Give three diagnostic criteria for the tissue shown in this photomicrograph. (3 marks) 2) Identify the tissue. (1 mark) 1) Blue-stained perineural connective tissue surrounding a fascicle of nerve fibres Presence of pale-stained axons surrounded by orange/yellow-stained neurokeratin (remnant of myelin sheath) Blue-stained endoneurium surrounding individual axons Orange/red staining nucleus of Schwann cells 2) Peripheral nerve A D B C 1) Identify the structures labeled A, B, C and D. (4 marks) 1) A – Myelin sheath B – Node of Ranvier C – Schwann cell cytoplasm D – Endoneurium .