Histology of the breast

بسم الله الرحمن الرحيم

The breast

By: P.D.Sanaa El-SherbinyMansoura University

Structure of mammary gland

1. clavicle 2. superficial fascia 3. glandular tissue 4. lactiferous duct 5. lactiferous sinus 6. areola 7. nipple 8. rib 9. intercostal muscles 10.pleura 11.pleural cavity

Histological structure

• The breast is formed of compound tubulo-alveolar glands covered by thin skin.

Mammary gland

• These are a pair of compound tubulo-alveolar glands to nourish new- borns

• The histological structure varies according to sex ,age & physiologic status

The covering skin shows:

1.Areola: central pink area of skin, deeply pigmented during pregnancy

2.Nipple: –An elevation in the center of the areola–It contains 15-25 opening of lactiferous

duct

1. Stroma–Interlobar septa: thick

• fibrous C.T. called “suspensory ligaments of cooper”

–Interlobular septa–Adipose C.T–Loose C.T :contain fibroblasts ,lymph-

ocytes , plasma cell & macrophages

2. Parenchyma– Contains duct system and secretory

unitsIn resting gland there is no secretory

units– Duct system consists of:1.Intralobular ducts: in the lobules ,lined

with 2 layers of cubical cells2.Lactiferous ducts: results from union of

intralobular ducts, dilated to form lactiferous sinuses , their proximal parts lined with st.col .Epith.

3.Lactiferous sinuses and terminal parts are lined with st. sq. epith.

During puberty• Their development forms one of the 2ry sex

characters1. Increase in vol. of ducts with cell

proliferation2. accumulation of adipose tissue in the

inter lobar and interlobular C.T.• All these changes are due to in ovarian

hormones with minimal appearance of alveoli at time of ovulation where estrogen reaches peak there is in adipocytes lipid acc.and breast in size

Resting non lactating glands

During pregnancy• The glands undergo intense growth

due to proliferation of ducts + production of secretory tubules and alveoli

• The C.T. stroma and adipose tissue decrease

• No visible signs of secretion except in late pregnancy

Secretory alveoli• Begin to appear at the 6th month of pregnancy• They are lined with columnar epith.• They are surrounded by myoepithelial cells• They contain colostrum in late months of

• Pregnancy ***Their mode of secretion is

apocrine • Mode of secretion.

Hormones controlling breast enlargement

1-Ovarian hormones :Estrogen increases during pregnancy acting on duct system

2-Progestrone by (corpus luteum ) 2-placental hormons act on secretory alveoli

• Placental Hormones are :progestrone ,placental mammotrophins 3-Anterior pituitary: growth h &prolactin h.

4-Suprarenal: glucocorticoids.

Lactating mammary gland• Consists of compound tubulo-alveolar• gland

1.Stroma is thin2.Parenchyma is formed of duct system and alveoli3.Alveoli are lined by columnar or cubical epith. Filled with

vacuolated milk secretion4.Milk secretion is controlled by5.Prolactin which stimulate alveolar cells secretion6.Oxytocin: contraction of myo-epithelial Cells ,squeezes

alveoli cause milk ejection

In lactation• Milk acc. In the lumen of secretory part

and ducts • Cells. Milk containing lipid vacuoles and

also protein vacuoles• Milk composition :

1. Lipid 4%2. Protein 1.5%3. Lactose 7%

• Colostrum : it contains less fat and more proteins and rich in antibodies (IgA)

Active lactating mammary gland

Lactating versus resting glands

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Histological structure of the skin

• Formed of two layers:

• 1- Epidermis • 2- Dermis

Types:1-THICK SKIN• EPIDERMIS: IS THICK:0.8mm in palm ,1.4 mm

in sole.• Contains 4 types of cells:• 1-keratinocytes (85% of cells)• 2-Melanocytes• 3-Langerhans cells• 4-Merkel cells• ِ�Arranged in five layers.

Layers of epidermis are • Stratum basale

(germinativum)• Stratum spinosum• Stratum granulosum• Stratum lucidum (may not

be present)• Stratum corneum

Thin skin

SWEAT GLANDS• Merocrine glands:• Allover the body• Secretory cells 2types• Clear cells cubical rich in

glycogen granules.• Dark with narrow basal part

with • Apical glycoprotein granules• Myoepithelialt cells• Ducts lined by 2layers of cubical

cells

• Apocrine glands:• Axilla,groin,pubic region• Secretory part similar • To mero. With • Wider lumen• Their ducts are lined • With 2 layers of cubical cells

but open into hair follicles• Secretion stim.by sex

• hormones

sweat glandsTwo types of sweat glands

– Eccrine• Not associated with hair follicle• Duct segment

– less coiled, leads to epidermis– Stratified cuboidal epithelium

• Secretory segment– in deep dermis or hypodermis– Secretory cells– Myoepithelial cells lie between

secretory cells, contraction expels sweat

– Apocrine• Found in limited areas• Empty into hair follicle

Structures of skin: hair follicle• Invagination of epidermis• Hair contains keratin and melanin• Dermal papilla

– Connective tissue invagination into bulb, has capillary network

• Matrix– Germinative layer adjacent to

dermal papilla– Also contains melanocytes

• Sebaceous gland– Secretion empties into hair

follicle• Arrector pili muscle

– Smooth muscle, inserts on hair follicle and base of epidermis

bulb

(dermal papilla)

The hair is formed of• Shaft: medulla, cortex and cuticle• The hair follicle is formed of :

• Inner root sheath formed of:• Cuticle ,Huxleys layer,Henles layer• Outer root sheath: identical with

Malpighian• Layer of epidermis

• Connective tissue sheath.

ECCRINE AND APOCRINE GANDS

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