Histology- Skin (Manakova)

1. Stratified squamous keratinized epithelium
2. Melanocytes
3. Langerhan`s cells
4. Merkel cells

Palms of hands and soles of feet

Synthesize acylglucosylceramide
Have RER+ GA = membrane coating granules (lammelar bodies)

Proteosynthesis--> keratohyaline granules.
Lamellar bodies release ceramide into the intercellular spaces.

Intermediate layer (eosinophilic)

Cells without nuclei
Have keratin crosslinked by flaggrin that form cell envelope together with ceramide.
Cells are joined by desmosomes

Low molecular weight cytokeratins: CK1- 8,14,17

Proteins of keratin containing intermediate filaments found in intracytoplasmic cytoskeleton of epithelial tissue.

High molecular weight cytokeratins: CK 10, 18

Develop form neural crest
Secrete cytocrine and produce melanin, melanosomes are injected into keratinocytes.
Function of melanin in keratinocyte: protect from UV radiation.
Melanin unit: apprx 1000/ square mm (2x higher in pigmented skin such as scrotum, anal and areola area)

Tyrosine--> dopa--> dopaquinone--> melanin

Catalyzed by tyrosinaze

Found in stratum basale, commonly in thin type og skin
Have dense granules containing neurotransmittors
Free nerve endings
Sensoric mechanoreceptors

Present in stratum spinosum of epidermis.
Derived from bone marrow and are APC- differentiate---> dendritic cells within lymphatic nodes (contain Bierbeck granules- rodlike)

Dense collagen connective tissue with elastic fibers
Main GAG: dermatan sulphate
Stratum papillare
Stratum reticulare
Appendages: glands, nails and hairs
Sensoric organs (Vater- Paccini and Meissner bodies)

Holocrine, compund alveolar
Not present in thick skin
Excretory ducts open into hair follicles except in:
- glans penis
- clitoris
- labia minora
- lip
- areola mammae

Simple coiled tubular glands
Dark cells (mucoid glycoproteins)
Clear cells (glycogen, basolateral labyrinth- transport of water and ions)
Duct directly on the surface
Duct with two layers of cuboid cells

Thick stratum corneum and stratum lucidum
Only eccrine sweat glands
Have sensoric ending- Meissner and Vater- Paccini bodies

Thin skin type
Hair follicle
All three types of skin glands:
- sebaceous glands
- eccrine sweat glands
- apocrine glands

Thin type
Hair follicles
Sebaceous and sweat glands
Thick hypoderm- adipose tissue

Thin type
Pigmentation in stratum basale- (high nr of melanocytes)
Smooth mm. cells in dermis

15-20 compound tuboalveolar glands
Ducts= lactiferous ducts---> lactiferous sinuses---> nipple (mammary papilla) and areola
Lobes--> lobules---> glandular alveoles surrounded by dense connective tissue and adipose tissue

Growth and differentiation of secretory ducts by: estrogen, progesterone, prolactin and placental lactogen.
Oxytocin from nerve stimulus stimulates contraction of myoepithelial cells--> rejection of milk

Decrease of prolactin level---> apoptosis---> regression

Proteins- merocrine secretion
Lipids- apocrine secretion
Sugar (lactose)- produced in GA
IgA- plasma cells