Histology of the Integument

Question 1

What cells are contained in the epidermis?

Answer 1

Epithelia

Question 2

What are the layers of skin?

Answer 2

1. Epidermis
2. Dermis
3. Hypodermis

Question 3

What cells are contained in the dermis?

Answer 3

Blood vessels, glands, nerves, some sensory receptors

Question 4

What cells are contained in the hypodermis?

Answer 4

Adipose

Question 5

What are the two sublayers of the dermis?

Answer 5

1. Papillary (superficial)

2. Reticular (deep)

Question 6

What are dermal papillae?

Answer 6

Knob-like projections of connective tissue that protrude into the epidermis to bind the layers together.

Question 7

What fiber type makes up the papillary layer?

Answer 7

Closely woven mesh of thin collagen and elastic fibers + some reticular - “dense connective tissue”

Question 8

What fiber type makes up the reticular layer?

Answer 8

Coarse, densely interwoven collagen fibers parallel to the surface. + elastic fibers - dense irregular connective tissue

Question 9

In what layer do you find hair follicles, sebaceous and sweat glands, lamellar pressure receptors (Pacinian corpuscle), and small bundles of smooth muscle?

Answer 9

Dermis: Reticular layer

Question 10

What are the downward projections of epidermis between dermal papillae called?

Answer 10

Interpapillary (rete) pegs.

Question 11

What are the 5 layers of developing stratified squamous keratinized epithelia?

Answer 11

1. Basale
2. Spinosum
3. Granulosum
4. Lucidum
5. Corneum

Question 12

How does the stratum basale appear?

Answer 12

Single layer of columnar-ish cells attached to the BM with hemidesmosomes. **The ONLY layer undergoing mitosis*

Question 13

How does the stratum spinosum appear?

Answer 13

Diagnostic spiny “intercellular bridges” are extensions of keratinocytes containing tonofilaments containing lamellar bodies (little lipid inclusions)
Lots of desmosomes!

Question 14

How does the stratum granulosum appear?

Answer 14

Somewhat flattened and irregularly shaped keratohyalin granules.
Lamellar bodies increase in number but become paler and less prominent.
Desmosomes and tight junctions

Question 15

How does the stratum lucidum appear?

Answer 15

Not visible in thin skin
Keratinocytes are flattened and barely stained
Sheets of lamellar lipid form a water barrier
Nucleus starting to degrade

Question 16

How does the stratum corneum appear?

Answer 16

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)

Question 17

What do melanocytes and melanosomes does?

Answer 17

Melanosomes are golden-brown melanin granules that are transferred to basal keratinocytes via melanocytes.

Question 18

How and where do Pacinian Corpuscles appear?

Answer 18

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.

Question 19

How and where do Meissner’s Corpuscles appear?

Answer 19

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.

Question 20

What is the difference between simple and compound glands?

Answer 20

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)

Question 21

How do mucous secreting cells appear? Why?

Answer 21

Pale, viscous and high in glycoprotein/glycogen

technically they secrete mucinogen not mucous

Question 22

How do serous secreting cells appear? Why

Answer 22

Dark, watery, some glycoprotein, minimal glycogen