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histological diagram of mammary gland- at puberty - during pregnancy -during lactation

histological diagram of mammary gland- at puberty - during pregnancy -during lactation
--click to enlarge the image



Parameters
Thyroid gland
Lactating mammary gland
Type
Endocrine (follicular gland having follicles and interfollicuiar cells with no ducts) Merocrine gland
Exocrine (compound tubulo- aiveoiar gland having alveoli and ducts) Apocrine gland
Parenchyma
Two lobes (many follicles in each)
Many lobes & lobules
covering
Double C.T. capsules
Adipose C.T. and skin
Epithelium of parenchyma
Follicles are lined with simple cuboidal cells
Microvilli (present)
Interfollicuiar C.T. tissue possesses C-cells
Alveoli are lined with either simple cuboidal or with simple columnar cells Absent
interalveolar C.T. possesses no specialized cells
Myoepithelial cells
Absent
Present
Secretion In the lumen
The colloid appears homogeneous
The milk appears vacuolated due to dissolved fat droplets
vessels In the stroma
Sinusoids
Capillaries
Ducts
Absent
Present
 comparison Between Thyroid A Lactating Mammary Gland


These are highly modified apocrine sweat glands of skin. The breast is formed of the following structures.
I.       The nipple or mammary papilla is covered with keratinized stratified squamous epithelium, which is pigmented. Epithelium of nipple rests on a layer of C.T., which Is rich In smooth muscles. The muscle fibres are mainly disposed circularly and less meriodinally.
II.    The areola (skin which surrounds the nipple) contains modified sweat glands called Montgomery glands and smooth muscle ceils.
III.  Main bulk of mammary glands, which is comprised of the stroma, parenchyma and ducts.

The histology of mammary glands varies with age, sex and physiological status.
   STROMA: Each breast is surrounded by a loose sub-cutaneous connective tissue from which numerous septae pass inwards to divide it into various lobes and lobules. The stroma is rich in fat and reticular fibers. The interlobar and interlobular connective tissue is dense and less cellular while intralobular connective tissue is loose and more cellular in nature. The various fibrous processes extend from dermis into connective tissue stroma. These supporting fibrous bands are called suspensory ligaments of Cooper.
. PARENCHYMA: It consists of 15-20 tubulo-alveolar or compound alveolar glands.
Each gland has its own excretory lactiferous duct, which opens independently on surface in the nipple .
At birth there is no difference in male and female breasts. In both, the gland is represented by only lactiferous sinuses and ducts.

At puberty the breasts of female become enlarged and ductal system is better developed.
After puberty alveoli and duct system develop to a considerable extent. The main bulk is formed by accumulation of adipose and collagenous tissue due to estrogens. At the tip of lactiferous duct many interlobular any intralobular ducts appear. The lobules are embedded in loose cellular intralobular C.T., which is rich In lymphocytes and plasma cells. In non-lactatlng adult female, mammary gland is represented by mainly the duct system (only the ducts are present in the lobes and lobules of the breast). In pregnancy and during lactation further development of ducts and alveoli occurs and milk accumulates in the alveoli.

Alveoli: These are lined with simple cuboidal epithelium In resting stage and columnar epithelium In late pregnancy and lactation. There is a distinct basement membrane with few myoepithelial cells between epithelium and basement membrane. Their contraction helps in the secretion of milk.

 DUCTS: The small ducts (intralobular) are lined with simple cuboidal epithelium, the larger (Interlobular) with simple columnar or stratified columnar epithelium. They also show some myoepithelial cells. There are 15-20 lactiferous (large ducts), one for each lobe. The larger ducts (excretory lactiferous ducts), before opening on the surface are slightly dilated (lactiferous sinuses) and are lined by keratinized stratified squamous epithelium.

PREGNANCY AND LACTATION: Due to high levels of progesterone, estrogen and prolactin, the development of secretory alveoli from the small intralobular and interlobular ducts takes places . While C.T. septa between the ducts and alveoli is thinned, the adipose tissue is also reduced. The alveoli are lined with simple cuboidal or simple columnar epithelium. The cytoplasm of these cells is rich in ribosomes. mitochondria, endoplasmic reticulum and dense secretory vesicles especially in the apical region of cell. These vesicles are rich in milk proteins. The number of secretory vacuoles and fat droplets is also increased. The lumen of alveoli is filled with milk and appears vacuolated due to dissolution of fat during histological preparations. The plasma cell population in intralobular C.T. increases more towards the end of pregnancy (which secrete ig-A antibodies).
The acini are surrounded by myoepithelial cells, which contract due to oxytocin in the circulating blood. There is no marked change in the histology of duct system. The color of areola and nipple darkens as a result of accumulation of melanin. The amount of C.T. stroma and adipose tissue, relative to parenchyma decreases considerably. During lactation, the milk produced by alveoli accumulates in their lumen and inside the lactiferous ducts. The epithelium of alveoli becomes small and low cuboidal. The cytoplasm of apices of cells contains many lipid droplets and protein containing vesicles.




tags :
Histology Of mammary gland
Histology Slide Of mammary gland
Histological Slide of mammary gland
 Histology mammary gland
mammary gland Histology Slide
mammary gland Slide
Slide of mammary gland
Normal Histology of mammary gland
Histology Of normal mammary gland
Human histology  mammary gland



tags :
Histology Of breast
Histology Slide Of breast
Histological Slide of breast
breast Histology
breast Histology Slide
breast Slide
Slide of breast
Normal Histology of breast
Histology Of normal breast
Human histology breast

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