PHY3111 Study Guide - Final Guide: Stratum Granulosum, Stratum Lucidum, Stratum Corneum
Document Summary
Stratum basale (stratum germinativum) part of malphigian layer. Single layer of cuboidal cells resting on basal lamina, numerous desmosomes and hemidesmosomes, intense mitosis, human epidermis renewed every 15-30 days depending on age/region of body/etc. , contains cytokeratin intermediate filaments. Consists of cuboidal to slightly flattened cells, cytoplasmic processes, numerous desmosomes, mitosis occurs here. 3-5 layers of flattened cells, cytoplasm filled with keratohyalin granules which contain histidine-rich proteins and cystine-containing proteins, also membrane-coated amellar granules which contain lipid, lipid excreted into intercellular space. More apparent in thick skin, translucent, thin layer of extremely flattened eosinophilic cells, organelles and nuclei no longer evident, cytoplasm consists of densely packed filaments embedded in an electron-dense matrix, desmosomes still evident. 15-20 layers of flattened non-nucleated keratinised cells, cytoplasm filled with keratin, cells are continuously shed at surface. About 100 per cm^2 over most of body, but 400-900 per cm^2 on face, forehead, and scalp.
