Histology of the Integument Flashcards
What cells are contained in the epidermis?
Epithelia
What are the layers of skin?
- Epidermis
- Dermis
- Hypodermis
What cells are contained in the dermis?
Blood vessels, glands, nerves, some sensory receptors
What cells are contained in the hypodermis?
Adipose
What are the two sublayers of the dermis?
- Papillary (superficial)
2. Reticular (deep)
What are dermal papillae?
Knob-like projections of connective tissue that protrude into the epidermis to bind the layers together.
What fiber type makes up the papillary layer?
Closely woven mesh of thin collagen and elastic fibers + some reticular - “dense connective tissue”
What fiber type makes up the reticular layer?
Coarse, densely interwoven collagen fibers parallel to the surface. + elastic fibers - dense irregular connective tissue
In what layer do you find hair follicles, sebaceous and sweat glands, lamellar pressure receptors (Pacinian corpuscle), and small bundles of smooth muscle?
Dermis: Reticular layer
What are the downward projections of epidermis between dermal papillae called?
Interpapillary (rete) pegs.
What are the 5 layers of developing stratified squamous keratinized epithelia?
- Basale
- Spinosum
- Granulosum
- Lucidum
- Corneum
How does the stratum basale appear?
Single layer of columnar-ish cells attached to the BM with hemidesmosomes. **The ONLY layer undergoing mitosis*
How does the stratum spinosum appear?
Diagnostic spiny “intercellular bridges” are extensions of keratinocytes containing tonofilaments containing lamellar bodies (little lipid inclusions)
Lots of desmosomes!
How does the stratum granulosum appear?
Somewhat flattened and irregularly shaped keratohyalin granules.
Lamellar bodies increase in number but become paler and less prominent.
Desmosomes and tight junctions
How does the stratum lucidum appear?
Not visible in thin skin
Keratinocytes are flattened and barely stained
Sheets of lamellar lipid form a water barrier
Nucleus starting to degrade
How does the stratum corneum appear?
VERY flat and closely packed
Nucleus is GONE
ONLY keratin remains in its place, forming a cornified cell envelope (considered compound when in conjunction w/ lipid)
What do melanocytes and melanosomes does?
Melanosomes are golden-brown melanin granules that are transferred to basal keratinocytes via melanocytes.
How and where do Pacinian Corpuscles appear?
Typically located deep in the reticular dermis or hypodermis. In a well-fixed section, the large (up to 1mm) distinct multilamellar oval-to-spherical corpuscles resemble the transversely cut surface of an onion.
How and where do Meissner’s Corpuscles appear?
small fusiform (oval) multicellular structures specifically located in the tips of some of the dermal papillae. They are com- posed of delicate cells that are arranged perpendicular to the corpuscle’s long axis.
What is the difference between simple and compound glands?
In simple glands the duct portion MUST be tubular. The secretory portion can take on diff morphologies. In compound glands the ducts can take on different morphologies as well (e.g. branching)
How do mucous secreting cells appear? Why?
Pale, viscous and high in glycoprotein/glycogen
technically they secrete mucinogen not mucous
How do serous secreting cells appear? Why
Dark, watery, some glycoprotein, minimal glycogen
