DEVELOPMENT OFMAMMARY GLAND By M.THILAKAR LS1154 M.SC IN LIFE SCIENCES SECOND YEAR BHARATHIDASAN UNIVERSITY TIUCHIRAPALLI.
WHAT IS MAMMARY GLAND..?? A mammary gland is an organ in female mammals that produces milk to feed young offspring. Mammals get their name from the word "mammary“.
MAMMARY GLAND IN MAMMALS… In Humans, the mammary glands are situated on the breasts. In ruminants such as cows, goats, and deer, the mammary glands are contained in their udders. The mammary glands of other mammals that have more than two breasts, such as dogs and cats, are sometimes called dugs.
ORIGIN OF MAMMARY GLAND Origin of Mammary Gland starts from Embryo. Embryo contain 3 layers. Ectoderm Endoderm Mesoderm
ECTODERMAL CHANGES… First sign of Development : Thickening of Ectodermal Cells. Serious Changes Occur in Ectoderm Layers. Mammary band, Mammary Streak, Mammary Line, Mammary Crest, Mammary hillock and Mammary bud
MAMMOGENESIS IN FETUS Maturation of Mammary Bud Coincided with the Embryo becoming Fetus. Fetus : Term reserved for Placental Mammals(Eutherians). Protherians (Egg Laying): Same Stage of Development as Eutherians. Metatherian : At the Time of Pregnancy.
PRIMARY SPROUT Mammary Bud into Primary Sprout. It is Destined to become a Opening in the teat. These Openings are : Galactophores. Each Galactophore is Pre determined by Primary Sprout from the Mammary bud. No. of Galactophores varey among the Species.
SECONDARY SPROUT From Primary Sprout. Destined to become a Mammary Duct. They become Hollow (Canalized) shortly before the Birth of the Calf. Contain Fat Pad More in Female. Less in Male.
FAT PAD Arises from Mesoderm of Embryo. Important for the Mammal sp of Cattle, Goat, Sheep.
EARLY MAMMOGENESIS IN HUMAN 3-5 Months of Fetal Development have : developed Mammary Bud. At about 5 Month : Surface of the Mammary bud Spreads out and a depression forms at the Surface. Forms Secondary Buds/Epthelial cords.
EPITHELIAL CORD Epithelial cords forms Lactiferous Ducts. Epithelial cords gradually develop and Branch at their Ends and each of them Correspond to a Lactiferous Duct or Opening in the Nipple ina Developed gland.
AT BIRTH Teats are Well Developed Secondary Sprouts are Canalized and have solid Core of the Cells at the end. These Cells continue to Grow and branch. Growth of Sprouts : Limited to the Area around the Gland Cistern. Non Secretory Cells
BIRTH TO PUBERTY Isometric development Pig : 25-30 Days. : (Similar to the Growth Rat : 40 Days. Rate of BOdy) Cattle : 6-8- Months. Length of this Preiod Human : 10-12 Years. Varrey among the Species. Gland increse in Size from Development of Fat Pad and Connective Tissues.
PUBERTY - CONCEPTION Female releaes FSH and LH from Pituitary gland. These Simulates Ovary to Synthesize and Releases the Sex Hormones. Estrogen (Estradiol) : stimulat the Mammary gland Proliferation. Ducts are Lenghtening and Branched.
TEB(TERMINAL END BUD)DUCT ELONGATES AND BRANCH OCCUR AT THE ACTIVELYGROWING END IN THE STRUCTURE KNOWN AS THE TEB Estrogen :Cells Multiply at the tip of TEB for Elongation Progesterone : Duct and Ductile Cells Multiply for the Widening of the Gland. At the time of Puberty : Both Hormones appear in Mammary Gland.
SHORT CYCLE MAMMALSEG. : RAT, MICE. Absence of Luteal Phase. Because they don’t have Coitus or other Simuli that causes the relaese of Prolactin. Estrus Cycle Mammary Gland Simulated by Estrogen from the Ovary in synergism with Prolactin and Aomatotrop[hin from Pituitary gland. Result : Lengthening and Branching of ducts to TEB. (or Alveoli until the Pregnancy)
LONG CYCLE MAMMALSEG : CATTLE, SHEEP, GOAT. Exhibit the Functional Corpora Lutea (it Secretes Progesterone during Luteal Phase) Progesterone synergizes aith Estrogen, Prolactin and Somatotrophin. During First several Cycles : Duct Lengthening, Branching and Eventually adifferentiation into Lobules and Alveoli takes place.
DURING PREGNANCY Major Portion of the Growth occur and it is Controlled by Hormones. Growth of Hormone is Slow at the Beginning But Accelerate the Growth rate. Non Pregnancy women contain Fat pads. During Pregnancy : Fat pads are Replaced by Ducts, Alveoli, Blood vessels and Connective Tissues.
DURING PREGNANCY CNTD… In Estrus Cycle Both of Hormones elevated during the Pregnancy because there is Lobluo Alveolor Growth is Absent. In Cow : > Progesteron eleveted through the gestation >estrogen eleveted only on the Part of the Seconf part of the Gestation. They Accelerate the rate of Cell Division in Mammary Gland (Especially in TEB)
SECRETION OF MILK Glucose get into Alveolor cells via Glucose Transporter (GLUT) Free Glucose Enters into Golgi Complex via GLUT where Combined with UDP-Galactose. Golgi Membrane : Not Permeable to Dissaccharides. So drows Water osmotiacally to Golgi Compartment.
SYNTHESIS OF HUMAN MILK Hexokinase Glucose ---------------- > Glu-6-Po4 Isomeize Glu-6-Po4--------------- > Pyruvate / Glycerol Glu-6-Po4 IsomeraseGlu-6-Po4 also Enter into Phosphate Shunt to Produce NADPH for Lipid Synthesis.Pyruvate enters into Mitochondria and Produce ATP.
COMPOSITION OF HUMAN BREAST MILK Fat : Total (g/100 ml)4.2 Fatty acids - length 8C (% )trace Polyunsaturated fatty acids (%)14 Protein (g/100 ml)total1.1 casein 0.40.3 a-lactalbumin0.3 lactoferrin (apo-lactoferrin)0.2IgA0.1IgG0.001 lysozyme0.05 serum albumin0.05 ß-lactoglobulin-Carbohydrate (g/100 ml) Lactose7 oligosaccharides0.5Minerals (g/100 ml) calcium0.03 phosphorus0.014 sodium0.015 potassium0.055chlorine0.043
COLOSTRUM This special milk is yellow to orange in color and thick and sticky. It is low in fat, and high in carbohydrates, protein, and antibodies to help keep baby healthy. Colostrum is extremely easy to digest, and is therefore the perfect first food for baby.