Mamogenesis sir fiaz

basics of mamogenesis are discussed here

1. Mamogenesis Submitted to: Sir Fiaz Submitted by: Abdul Wahab Abdul qadeer Abdul ahab bajwa 1

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. 2

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. 3

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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 6

7. Embryonic and fetal development: Embryonic stages include Ectodermal layer outer most Mesodermal layer middle layer Endodermal layer inner layer 1 st step thickening of cells around the ectodermal layer on ventral sides. mammary glands develop from ecto and mesodermal layers between rear legs. 7

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 8

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 9

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. 10

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12. Birth to puberty: At birth these structures can be seen: Teats Secondary sprouts Few tertiary sprouts Non-secretory tissues Sprout growth is limited to gland cistern. Male/female glands similar but fatty pad more developed in females. 12

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. 13

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. 14

15. During pregnancy: During pregnancy alveoli commence to replace the fatty pad throughout the udder. Isometric growth: During 1 st and 2 nd 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. 15

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. 16

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. 17

18. Comparison among mammals : 18

19. Conti… 19

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