Lecture 41 4/24/24 Flashcards
How are glands classified?
-exocrine vs endocrine
-multicellular vs unicellular
-tubular vs acinar shape
-apocrine vs merocrine vs holocrine secretion
How do apocrine and eccrine glands differ?
apocrine:
-associated with primary hair follicles
-duct empties to hair follicle
-apocrine secretion
-throughout haired skin
-thermoregulation only in horses and cows
-secretions mix with sebum to form protective skin layer
eccrine:
-not associated with hair follicles
-duct empties to skin surface
-merocrine secretion
-specialized locations
-thermoregulation in all mammals
How are apocrine and eccrine glands similar?
-single layer of cuboidal/columnar epithelium surrounded by myothelium
-simple tubular - coiled shape
What are the specialized locations for eccrine glands?
-footpads of dogs and cats
-frog of ungulates
-nasal planum of cows
-snout and medial carpus of pigs
What are the characteristics of mammary glands?
-special apocrine gland
-produce secretions high in protein and lipid
What are the characteristics of ceruminous glands?
-special apocrine gland
-located in external ear canal
-produces cerumen/ear wax
-cerumen lubricates, waterproofs, entraps materials, and is antimicrobial
What are the characteristics of the apocrine glands of the anal sac?
-special apocrine gland
-located next to anal sacs
-open to anal skin or into sac
-allow for territorial markings
How do special/modified apocrine glands differ from normal apocrine glands?
they are not associated with hair follicles
What are the characteristics of sebaceous glands?
-holocrine secretion
-acinar shape
-multicellular
-exocrine
-associated with hair follicles (mainly primary)
-not found on footpads or nasal planum
What is a Meibomian gland?
sebaceous gland associated with the eyelids
What are the characteristics of the tail gland?
-special sebaceous gland
-found in dogs, cats, and other carnivores
-found in both sexes on the dorsal aspect of tail
What are the characteristics of perianal glands?
-special sebaceous gland
-associated with hair follicle
-resemble hepatocytes
-found on perianal skin, proximal tail, lumbosacral region, lateral to prepuce, and along ventral midline
-absent in cats
-allow for territorial markings
What are the layers of the panniculus and subcutis, from most superficial to least?
-panniculus adiposus: adipose tissue
-panniculus carnosus: skeletal muscle
-subcutis: adipose tissue
What are the characteristics of the panniculus and subcutis?
-form the deepest and thickest layer of skin
-absent in the lips, cheeks, eyelids, ear canal, and anus
-attached to underlying bone and muscle
What are the functions of the panniculus and subcutis?
-energy storage
-thermoregulation/insulation
-protective padding
-maintain surface contours
What are the components of the subcutis and panniculus?
-white adipose
-panniculus muscle
-blood vessels
-nerves
*NO LYMPHATICS
What are the characteristics of the nose in carnivores?
-aka planum nasale
-keratinizing stratified squamous epithelium
-thick keratin layer
-no hair follicles
-no glands
What are the characteristics of the nose in cows/small ruminants?
-aka planum nasolabiale/planum nasale
-keratinizing stratified squamous epithelium
-thick keratin layer
-no hair follicles
-eccrine glands present to moisten the surface
What are the characteristics of the foot pads?
-thickest epidermis on body
-often highly pigmented
-thick keratin layer
-keratin layer is smooth in cats, papillary in dogs
-prominent dermal papillae interdigitate with epidermal rete pegs
What are the characteristics of the foot pad dermis?
-no hair follicles
-numerous eccrine glands
What is the main characteristic of the foot pad hypodermis?
lots of adipose tissue; digital cushion
What are the characteristics of carnivore toenails?
-nail bed consists of stratified squamous epithelium and thick, dense keratin
-nails are supported by bone
What is the equine hoof?
insensitive keratinized layer
What is the equine hoof wall?
epidermis that makes the hoof
What is the perioplic epidermis?
epidermis at the junction of the skin and the hoof
Which tissues are present and interdigitate at the epidermal-dermal junction of the hoof?
-stratum lamellatum/epidermal laminae
-lamellar corium/dermal laminae
How do the primary and secondary laminae differ?
-primary laminae are the main large laminae
-secondary laminae are smaller and branch off the primary laminae
Which laminae keratinize to form the hoof?
primary laminae
What are the components of each primary or secondary laminae?
-insensitive epidermal component
-sensitive dermal component
How do the hooves of ruminants and pigs differ compared to horses?
-technically have claws instead of hooves
-no secondary laminae
-more primary laminae
