Histology Flashcards
Layers of the epidermis (5)
Top to bottom:
- Stratum corneum
- Stratum lucidum (only in thick skin)
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Functions of integumentary system (6)
- Forms a tough protective barrier
- Energy reservoir: adipose tissue in subcutaneous layer
- Initiate an immune response
- Site of wound healing
- Excretion of metabolic products
6.
Histology of Psoriasis
- Acanthosis (epidermal hyperplasia: abnormally thick)
- Parakeratosis (nuclei retention in the stratum corneum)
- Munro microabcesses: collections of neutrophils in the stratum corneum
- Thinning of the epidermis above elongated dermal papillae (results in Auspitz sign)
Histology of Lichen Planus
inflammation of the dermal epidermal junction with a saw-tooth appearance
Pemphigus Vulgaris
- Suprabasal blisters
- acantholysis (separation) of stratum spinosum
- Basal layer has tombstone appearance
- Immunofloresence highlights IgG surrounding keratinocytes (fish net appearance)
Visual features of a motor neuron?
Multi-polar (many dendrites, but only ever one axon), large, pale nucleus (un-condensed DNA), obvious nucleolus.
Visual identification of an astrocyte
Cytoplasmic process ends on a blood vessel or a capillary
What makes myelin in CNS vs PNS?
CNS: oligodendrocyte
PNS: Schwann cells
Which layer of connective tissue is particularly important for the blood/brain barrier?
Perineurium
Ganglia
Where ALL the nerves and neuronal cell bodies in the PNS are found.
Endoneurium
Found within the nerve bundle
How to differentiate dense connective tissue from neural tissue?
Both have an organized, wavy appearance, but neural tissue has spaces that represent the nodes of Ranvier.
Capsule/satellite glial cells
Protective function, support for neuronal cell bodies
Nissle bodies
- granular, basophilic substance found in neurons (esp large neurons)
- made up of rough ER
- site of protein synthesis
What are the distinguishing features between basal and squamous cell carcinoma?
- Squamous cell carcinoma lacks the palisading seen in basal cell carcinomas.
- Squamous cell will show many odd looking cells mixed in with some mature keratinocytes (originated higher in the epidermis).
What is the histological hallmark of melanoma?
A nest of melanocytes, distinguishable because they tend to be wrapped in a pale bubble.
What immunohistochemical stains are used to diagnose melanoma, and to what specifically do they bind? (2)
- HMB-45 (marker of melanocytes, positive looks like red granules)
- S-100 (a calcium binding protein present in melanocytes)
Distinguish melanoma from nevi histologically.
Benign nevi show mature keratinocytes with no other oddballs mixed in, and no mitosis.
What are the two stains used to identify fungal stains?
GMS and PAS.
Glassy bodies are characteristic in histology of what diagnosis?
Molluscum contagiosum
How are purkinje fibers distinguished from cardiac muscle?
Purkinje fibers stain paler.
How do you distinguish cardiac and skeletal muscle (both striated)?
The nuclei are on the periphery in skeletal muscle (many nuclei) while cardiac muscle nuclei are in the center (1 or 2 nuclei). Cardiac muscle also branches.
Where are neurons always found in the periphery?
In a ganglion.
What is distinctive about the nucleus in smooth muscle?
It assumes a corkscrew shape when the muscle contracts because it gets caught in the middle.
