Mammals – Part V

VERTEBRATE ZOOLOGY (VZ Lecture33 – Spring 2012 Althoff - reference PJH Chapter 21)

Bill Horn

Skin & Glands

Unique Mammalian Characteristics Associated

with the Skin

• HAIR• SWEAT GLANDS• SEBACEOUS GLANDS• SCENT GLANDS• MAMMARY GLANDS

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FDVM p60, Fig. 5.2

Hair• Has its origin in the dermal layer

(dermis)• Consists of dead epidermal cells

strengthened by keratin (a tough, horny tissue made of protein)

• Functions: a) ___________ b) sensory c) camouflage d) defense e) aggression

1

Cells “invaginate”,In the epidermis

= epidermis= dermal = subcutaneous

HAIR DEVELOPMENT

2

“Hair” projectsdownward aswell as grows up

3

Rooted insubcutaneouslayer

Mescenchmalaggregation Mescenchmal

aggregation

Pigmentcells Hair

cone

Papilla

Hairbulb

Sweat Glands

• Has its origin in the dermal layer (dermis)• Functions: ______________

_______________• Two types: a) eccrine--separate duct at

surface; usually well distributed over bodyb) apocrine--duct at exit point (pore)

of hair; armpits, anogenital region, naval, nipples, & ears; in ears: modified to produce wax

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FDVM p60, Fig. 5.2

Eccrine sweat pore

ApocrineSweat duct

Pore

Sweating part ofapocrine sweat gland Secreting part of

eccrine sweat gland

Sweat Glands…con’t• Distribution over body surface varies

a) _____________--all over bodyb) _____________--pads of feetc) _____________--feet and/or venter

d) ____________________ --do not have any e) ____________________ --do not have any

Sebaceous Glands• Associated with _________________• Produce and secrete oils a) positioned by erector

pili muscles b) muscle moves, forces oil aroundshaft of hair

• Functions: a) ____________________ b) ______________________

• Lanolin produced by sheep unique• Hartner’s gland: lub for eyes & nictitating membrane

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FDVM p60, Fig. 5.2

Sebaceous gland

Scent (musk) Glands

• Either modified sweat glands or modified sebaceous glands

• Functions: a) ______________b) ______________ c) ______________ d) ______________

• Distribution varies (chin-to-tail): a) skunk: anal region b) wolves & coyotes: top of tail c) ungulates: pre-orbital area

Mammary Glands

• Also known as ____________• Elaborate , elongated duct system with

hollow sacs at end: a) alveolus--individual sac b) lobules of andular tissue--group of alveoli

• Function: milk production

clavicle

intercostalmuscle

LACTIFEROUS DUCTLACTIFEROUS SINUS

AREOLA

NIPPLE

pleura

pleuralcavity

pectoralismajor

rib

LOBULES of ANDULAR TISSUE

ADIPOSE TISSUE

MAMMARYTISSUEshowingindividual

__________

LOBULEOF

ALVEOLI

LOBULEOF

ALVEOLI

Milk __________ “_________”

Mammary Glands…con’t

• Always on ventral sidea) primates: 2 thoracic mammaeb) perissodactyls: 2 inguinal mammaec) most rodents: 5 pairs on belly

(chest to groin)d) NA opossum: 13 (12 in circle, 1 in

center of circle)e) whales: mammary grooves

Milk Production• ________ is hormone that stimulates milk

production• ________ is hormone that stimulates milk letdown• Milk content varies in protein & fat content a)

__________________b) __________________c) ____________ (in kangaroos)