basics of mamogenesis are discussed here

1. Mamogenesis
Submitted to: Sir Fiaz
Submitted by: Abdul Wahab
Abdul qadeer
Abdul ahab bajwa
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2. Contents:
• Introduction
• Steps for Mamogenesis
• Embryonic and fetal development
• Birth to puberty
• Puberty to conception
• During pregnancy
• During the dry period
• Comparison among mammals
• Hormonal control of mamogenesis.
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3. Introduction:
Mamogenesis:
Delelopment of mammary glands which starts days
after conception and continues until peak production
is achieved.
• Takes place both in male and female before birth.
• Fatty pad can be felt in both and differentiation
after birth under the influence of endocrine
hormones.
Lactogenesis: onset of lactation.
Lactopoesis: maintenance of lactation.
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6. Steps for Mamogenesis:
• Serial changes in thickening occur with time.
Days of embryo Length Structure formed
32 14mm mammary band
34 16mm mammary streak
35 17mm mammary line
37 19mm mammary crest
40 21mm mammary hillock
43 25mm mammary buds
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7. Embryonic and fetal development:
• Embryonic stages include
1. Ectodermal layer outer most
2. Mesodermal layer middle layer
3. Endodermal layer inner layer
1st step thickening of cells around the
ectodermal layer on ventral sides.
mammary glands develop from ecto and
mesodermal layers between rear legs.
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8. Conti…
Bovine Ovine
4 Buds 2 Buds
Mammary buds are the structures, determinant of
the no. of mammary gland in a specie, from which
mammary gland arise.
Mammary buds
Primary sprout (primary mammary buds)
Secondary sprout (secondary mammary buds)
Mammary ducts
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9. Conti…
• Primary sprout is forerunner of teats and gland
cistern, designed to form galatophore.
• No. of primary sprouts is equal to no. of
galatophores, which vary among species.
• Proliferation of primary sprout results in canal
which becomes gland cistern at distal end.
• Further budding through primary sprout leads to
secondary sprout and then finally mammary
ducts, become hollow or canalized before birth.
Galatophore : a duct carrying milk
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10. Conti…
• All development takes place in fatty pads.
• Non-glandular portion is well developed at
time of birth.
• Very early in life females develops more
extensive fatty pad around mammary
structures than male calves.
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12. Birth to puberty:
• At birth these structures can be seen:
1. Teats
2. Secondary sprouts
3. Few tertiary sprouts
4. Non-secretory tissues
• Sprout growth is limited to gland cistern.
• Male/female glands similar but fatty pad
more developed in females.
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13. Conti…
Puberty:
Age of sexual and behavioral maturity.
• When progesterone level reaches to 1ng/ml of
serum.
• Ductular system fully developed.
• Fatty pad enlarged.
• No secretory activity at all.
• CT enlarged.
Repetition of estrous cycle may induce
enlargement of ducts.
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14. Puberty to conception:
FSH, LH, estrogen, progesterone
synergistic effects
prolactin and somatotrophin
Finishing to ductular growth.
• Alveoli are not formed until conception or
pregnancy is established.
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15. During pregnancy:
• During pregnancy alveoli commence to
replace the fatty pad throughout the udder.
Isometric growth:
During 1st and 2nd trimester growth is same as
body weight.
Allometric growth:
During last trimester growth is more than
body weight due to high PG. Most visible in
last month.
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16. Conti…
• Ductular growth still continues but most
growth occurs in lobule-alveolar portion.
• Significant quantities of secretions begins to
accumulate between 7-9 months of gestation.
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17. During the dry period:
• There is marked degradation and loss of alveolar
epithelial cells.
• Although alveoli are lost, myoepithelial and CT
remains.
• After involution of udder only duct system
remains.
• Cows become normally pregnant during this
period, as pregnancy stimulates udder growth
complete involution will not occur due to
pregnancy.
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18. Comparison among mammals :
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19. Conti…
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