Skin and mammary gland

Question 1

6. Thick hairless skin (HE)

Answer 1

EPIDERMIS:
- epithelium: stratified keratinized squamous
DERMIS:
- fibro-elastic CT
- dermal papillae + epidermal ridges
- papillary layer under epidermis
- fibroblasts, macrophages, mast cells, leukocytes
- deeper dense irregular CT + collagen + elastic fibers⇒ reticular layer
HYPODERMIS:
- loose fatty CT
- retinacula cutis⇒ strong CT strands through hypodermis
- eccrine sweat glands ⇒ coiled tubular glands

Question 2

Hair follicles

Answer 2

• tubular invagination of epidermis
  1. distal part
  2. isthmus
  3. infundibulum
• hair bulb⇒ enclose vascular dermal papillae
• germinal matrix⇒ epithelium around dermal papillae
• external root sheath⇒
• glassy membrane⇒ separates external root sheath and CT
• internal root sheath⇒ contains eosinophilic trichohyalin granules
• hair shaft⇒ inner 3 epithelial layers
  
  • medulla⇒ keratinized, vacuolated cells
  • cortex ⇒heavily keratinized
  • hair cuticle⇒ hard thin keratin plates
• holocrine sebaceous glands⇒ between infundibulum and isthmus
• arrector pili muscle⇒ originate in papillary dermis

Question 3

13. Skin of axilla (HE)

Answer 3

• apocrine sweat glands ⇒ straight course, empty into hair follicles

Question 4

Pigmented skin

Answer 4

• Melanocytes ⇒ synthesize melanin pigments
  
  • located between basal epithelial cells in epidermis
  • numerous in genital skin
  • long cytoplasmic processes
• Melanin ⇒ migrate into cytoplasmic processes⇒ cytocrine secretion
  
  • dar brown deposits in stratum basale + spinosum but not disappear in upper epithelial cells bc melanin granules fuse with lysosomes

Question 5

127. Mammary gland- non lactating (HE)

Answer 5

• breats consists of 15-20 lobes of compound tubuloalveolar modified apocrine sweat glands in dense CT + adipose tissue
• from each lobe ⇒ 1 lactiferous duct open on surface of nipple
• lactiferous duct: lined by stratified columnar/cuboidal epithelium
• lactiferous sinuses near opening, lined by stratified squamous epithelium
• each lobe ⇒ several lobules ⇒ alveolar ducts⇒ lined by simple cuboidal epithelium
• loose, cellular, highly vascular interlobular CT
• dense collagenous, less cellular, interlobular CT

Question 6

125. Mammary gland- lactating (HE)

Answer 6

• at end of interlobular duct ⇒ proliferation of alveoli
• intra and interlobular CT diminish
• thin CT septa between lobules
• in apical part of milk-secreting epithelial cells ⇒ lipid droplets⇒ leave cells by apocrine secretion
• milk proteins are released by exocytosis
• active milk-secreting cells ⇒ small and low cuboidal
• CT⇒ fibroblasts, mast cells, macrophages, lymphocytes, neutrophils, eosinophils
• Plasmacytes ⇒
  
  • active stimulated B cells
  • around ducts and alveoli
  • source of immunoglobulins present in milk
  • nuclei round and cartwheel arrangement of heterochromatin