Histology: Integumentary System

Front 1

skin gen

Back 1

1. epidermis: SS keratinized
2. dermis
3. appendages: hair follicles, sweat and sebaceous gland
4. specialized: hoof, horn, claws

Front 2

stratum germinativum of epidermis

Back 2

1. stratum basale: single layer of cuboidal or columnar cells resting on the basal lamina
2. stratum spinosum: several layers of polyhedral cells tightly adhered by numerous desmosomes

Front 3

stratum granulosum of epidermis

Back 3

several layers of flattened cells
-w/ keratohyalin granules

Front 4

stratum lucidum of epidermis

Back 4

occurs only in non-hairy skin: foot pad

Front 5

stratum corneum of epidermis

Back 5

dead, keratinized cells:
- protein, keratin which provide structural support to the cell

Front 6

stratum disjunctum of epidermis

Back 6

-most superficial layers of stratum corneum that undergo constant desquamination

Front 7

melanocytes of epidermis

Back 7

-located among cells of stratum basalae and spinosum
- produce melanin

Front 8

dermis

Back 8

- superficial and papillary layers
- transversed by nerves, blood and lymph vessels
- smooth mm: areas such as scrotum, penis and teats
- skeletal mm: peneatrate dermis, cutaneous trunci allows voluntary movement of skin

Front 9

papillary layer of dermis

Back 9

- loose CT
- network: fine collagen, elastic and reticular fibers
- predominant cells: fibrocytes, mast, plasma, macrophages

Front 10

reticular layer of dermis

Back 10

- dense irregular CT
- large bundles of collagen fibers

Front 11

hypodermis (subcutis)

Back 11

- loose: collagen and elastic
- adipose tissue:
1. small clusters
2. panniculus adiposis: large mass of fat

Front 12

hair

Back 12

- doesn't cover: pads, hooves, glans penis
- flexible keratinized structure produced by hair follicle
- part within the follicle is the root: has terminal, hollow knob called the bulb which is attached to the dermal papilla

Front 13

hair shaft

Back 13

- free part of hair above skin surface
- 3 layers: cuticle, cortex and medulla
- pattern of surface of cuticular cells and cellular arrangement of medulla: species specific, used for medicolegal purposes

Front 14

cuticle of hair shaft

Back 14

formed by single layer of flat, keratinized cells

Front 15

cortex of hair shaft

Back 15

- layer of dense compact keratinized cells with their long axis parallel to the hair shaft
- pigment granules in cells

Front 16

medulla of hair shaft

Back 16

- forms the center of hair
- loosely filled with cuboidal or flattened cells
- root: solid
-shaft: air vacuoles among cells

Front 17

internal root sheath of hair follicle

Back 17

1. internal root sheath cuticle: overlapping keratinized cells
2. granular epithelial layers: 1-3 layers of keratinized cells rich in trichohyaline granules
3. pale epithelial layer: single layer of keratinized cells

Front 18

external root sheath of hair follicle

Back 18

-several layers of cells similar to stratum spinosum
- covered by glassy membrane
- entire epithelial sheath enclosed by CT sheath

Front 19

dermal papilla of hair follicle

Back 19

-CT directly under the hair matrix
- richly supplied by blood vessels and nerves

Front 20

hair matrix of hair follicle

Back 20

- comparable to germinativum cells
- give rise to the cells that keratinize (soft form) to form the hair shaft

Front 21

arrector pili m of hair follicle

Back 21

- associated with most of the follicle
- bundles of smooth m attached to the CT sheath of the hair follicle
- connect to papillary layer of the dermis
- innervated by autonomic nerves

Front 22

sinus or tactile hair follicles

Back 22

- whiskers
- highly specialized
- blood-filled sinus between the inner and outer layer of the dermal sheath
- skeletal mm attached to the outer sheath of the follicle: allow some voluntary control
- numerous n bundles penetrate the dermal sheath

Front 23

sebaceous glands

Back 23

- simple or compound alveolar
- associated with hair follicles
- ducts open into pilosebaceous canal
- hairless areas: ducts empty directly onto surface of skin
- holocrine release of sebum

Front 24

secretory units sebaceous glands

Back 24

solid mass of ependymal cells enclosed by a CT capsule

Front 25

sebum of sebaceous glands

Back 25

- mitotic activity takes place in the basal layer
- as the cells move inward, they enlarge and accumulate lipid droplets
- sebum derived from disintegration of these cells

Front 26

examples of sebaceous glands

Back 26

1. infraorbital
2. inguinal
3. interdigital gland of sheep
4. preputial and circumanal glands of dogs

Front 27

sweat (sudoriferous ) glands

Back 27

1. apocrine and merocrine

Front 28

apocrine sweat glands gen

Back 28

-simple coiled tubular
- secretory: large lumen lined with flattened cuboidal to low columnar cells
- myoepithelial cells between secretory cells and basal lamina

Front 29

apocrine sweat glands in different species

Back 29

1. domestic animals: throughout most of the skin
2. horses; secrete abundantly, produce sweat during exercise and at high temperature

Front 30

merocrine sweat glands

Back 30

- simple tubular
1. carnivores: footpads
2. cows: planum nasolabiale
3. pigs: carpal glands

Front 31

mammary glands gen

Back 31

- compound tubulo-alveolar
- myoepithelial cells contract in response to oxytocin, causing a letdown of milk into duct system
- interstitial CT provides structure and contains vessels and nerves

Front 32

mammary glands secretory stage

Back 32

- simple columar cells contain fat droplets and vesicles filled with micelles of milk proteins
- vesicle released into and fill lumen
- at end of secretory cycle the epithelium becomes low cuboidal

Front 33

duct system of mammary glands

Back 33

1. intralobular: simple cuboidal
2. interlobular: stratifed cuboidal
3. lactiferous sinus: stratified cuboidal
4. teast sinus and papillary duct: stratified squamous

Front 34

digital organ and hoof

Back 34

- hard keratin
1. hooves: horses, ruminants and pigs
2. cornual horns: ruminants
3. claws/ nails: carnivores

Front 35

digital pads

Back 35

- carnivores
-epidermis: highly keratinized, hairless
- dermis: coiled merocrine glands
- SQ: masses of adipose tissues enclosed in collagen and elastic fibers

Front 36

chestnut and ergot

Back 36

tubular and intertubular horn