Silde Set #2 Flashcards
What is the origin of the mammary gland?
embryonic ectoderm
What are the three germ layers of the mammary gland?
Ectoderm: (outer) skin, epidermis, dermis, mammary gland
Mesoderm: (middle) muscle, blood, connective tissue
Endoderm (inner) internal organs, intestine, stomach
What is the modified skin gland called?
Exocrine gland (secretes to the outside)
What are the three types of exocrine glands?
1) Holocrine (whole) where nucleus and cytoplasm secreted in toto
2) Merocrine (partial) components secreted
3) Aprocrine (a part) portion of cells contents.
What type of exocrine cells types makes up the mammary gland?
aprocrine and merocrine gland
What are the 6 stages of mammary development that happens internally?
Band - Thickening of the embryonic ectoderm to form a single layer of cells (band) on each side between fore and rear limb buds (32 days)
Streak - Thickening of the band to form a distinct streak between limbs (34 days)
Line - Rapid stage of differentiation of the streak to form a linear mound of epidermal cells between limbs (35 days)
Start adding on layers
Crest - Along the Line in certain areas, cells proliferate, whereas others do not; inguinal vs pectoral vs abdominal (37 days)
Hillock - Rapid proliferation of cells in crest into a hillock (sphere) in underlying mesoderm (40 days)
Pretty large embryo
Bud - Further proliferation of the hillock sphere into a bud of cells (43 days) Becomes the future mammary gland.
Name of the game is to just keep adding cells to get to the bud of the final stage.
Proliferation =
numbers
Differentiation =
function
What is the end product of the 6 stages of mammary development?
thickening of the ectoderm
What are the 6 stages of fetal mammary development?
Early Teat Formation
Primary Sprout
Bud reaches a spherical shape and begins further differentiation
Lenticular portion
Conical shape
Will become opening of teat = galactophore
Males develop through the primary sprout
Surge testosterone from fetal testes pinches off the neck of the sprout.
Secondary Sprouts
Formation of secondary sprouts
Cells multiplies and branch
Will become large milk ducts
More proliferation
Canalization of Primary Sprout
Cells in the center of the sprout die due to lack of nutrients (apoptosis)
Not enough blood flow and thus not enough nutrients for certain cells so the selective cell process turns on to get rid of the cells in order to not cause more damage.
Angiogenesis vessel development into these regions where cells need nutrients to keep them going (essentially blood supply growth)
Will become gland and teat cistern
Development of Gland and Teat Cisterns
Fat pad existence allows for mammary growth, by giving that space for the ducts to be developed. Not too much and not too little.
Contribution from mesoderm (connective tissues, adipose, tissue, blood)
Mammary fat pad development is critical for room to accommodate mammary gland growth.
The fat pad originates from the mesoderm (mesenchymal tissue)
Development of Median Suspensory Ligament
Formation of median suspensory ligament
Main/Primary support from mammary gland
Composed of elastic and fibrous connective tissues
Fibroblasts - produce elastin and collagen to create ligament (MSL) in mammary gland
Lateral ligament and lamellar plates also form.
What cells produce elastin and collagen to create the median suspensory ligament in the mammary gland?
Fibroblasts
How far in stages are male and female developed identically?
up the mammary bud stage
What growth type is when prepubertal mammary gland growth is similar to the growth of the body?
isometric growth
Where is the duct system extended into?
the fat pad
What species have limited duct growth?
rabbit, dog, cat
