Stratum Spinosum (Prickly layer)

Stratum basale (stratum germinativum)—deepest layer

i. Single layer of mitotically active cells

ii. Give rise to keratinocytes (youngest)

iii. Includes melanocytes and some Merkel cells

b. Stratum spinosum (Prickly layer)—weblike network of cells formed by intermediate filaments attached to desmosomes

i. Comprised of keratinocytes

ii. Includes melanin granules and Langerhans cells

c. Stratum granulosum—thick; 3-5 cell layers; keratinocytes are modified

i. Flattened; nuclei and organelles lost

ii. Keratohylaline and lamellated granules accumulate

iii. Lamellated granules are glycoproteins, released into extracellular space, that reduce water loss

iv. Cells more resistant to destruction

d. Stratum lucidum—a few rows of clear, flattened, dead keratinocytes; layer occurs only in thick skin

i. Keratohyalin granules—gummy substance associated with keratin filaments

ii. Cells aggregate in parallel arrays

e. Stratum corneum (Horny layer)—outer most layer; most of epidermis thickness

i. 20-30 cell layers thick

ii. Keratin, thickened plasma membranes and glycoproteins protect against abrasion and loss of water

iii. Cornified or horny cells—remnants of cells from this layer


via Lecture 7: Integumentary System.

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  1. […] Stratum Spinosum (Prickly layer) […]

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