11 topics with brief reviews: definitions, key facts, and class questions.
The "Skin and its appendages" section is dedicated to the largest organ of the human body. Here we examine in detail the embryonic development, layer-by-layer structure of thick and thin skin, as well as the histology of its appendages: sweat and sebaceous glands, hair, and nails.
Special attention is paid to the epidermis and its cellular composition. You will learn how the keratinization process takes place, what barrier role the basement membrane plays, and how the dermis is structured with its complex system of blood supply and innervation.
In practical classes and exams, you are most often asked to compare slides of thick and thin skin, list the cell differons of the epidermis (from keratinocytes to Langerhans cells), and explain the types of secretion of skin glands. This section will help you quickly structure your knowledge, learn to read histological slides, and answer instructors' questions with confidence.
They develop from the surface ectoderm by forming epithelial buds that grow into the dermis. Furthermore, merocrine glands develop directly from the epidermis, while apocrine glands develop from outgrowths of the hair follicle.
In which type of skin is the stratum lucidum of the epidermis present?
The stratum lucidum is present exclusively in the epidermis of thick skin (on the palms and soles).
Why do people have different skin colors despite having the same number of melanocytes?
Skin color is determined not by the number of melanocytes, but by the activity of their organelles — melanosomes. In people with dark skin, melanosomes are larger and contain more melanin.
Why is the stratum lucidum called that and why does it appear transparent?
In this layer, the light refractive indices of intracellular proteins and intercellular lipids completely coincide. As a result, the boundaries between individual cells visually blur, creating the effect of a homogeneous shiny band.
Why do surgeons make skin incisions along Langer's lines?
An incision parallel to tension lines (Langer's lines) does not cross collagen bundles, but merely spreads them apart. This prevents wound edge gaping and promotes the formation of a thin, cosmetic scar.
Master the entire topic in the "Histology" course
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