Chapter 15 Puerperium and Lactation AVS 222

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Chapter 15 Puerperium and LactationAVS 222
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Puerperium

• The period after parturition when reproductive
  tract repairs itself and returns to its
  non-pregnant condition (Uterine involution)
• Become prepared for another pregnancy
• Begins immediately after parturition and recovery
  period varies among species
• Short and smooth recovery period is desirable

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Events of Puerperium

• Myometrium contraction and expulsion of lochia
• Endometrial repair
• cyclcity
• Elimination of bacterial contamination

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Stage 1 Myometrium contraction and expulsion of
lochia
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Stage 2 3 Endometrial repairResumption of
ovarian function

• Necrosis of caruncular tissues
• Sloughing of the caruncular tissues
• Reorganization of uterine endometruim
• First postpartum ovulation

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Stage 4 Elimination of bacterial contamination

• Continuation of uterine contraction
• Rise in Estradiol and increase in leukocytes
• High degree of

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Lactation
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The Mammary Gland
Exocrine gland common to all mammals
Function nourish the neonate - Food source
fat, protein, sugar (CHO), vitamins, minerals,
water - Protection immunoglobulins
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The Mammary Gland

• Loosely considered part of the reproductive
  system
• Serves a reproductive function nourishment
  of the neonate survival of species.
• Relies on same endocrine (hormonal) support for
  development and function.
• Example gonadal steroids, prolactin, etc.

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The Mammary Gland
Embryo Origin The mammary gland is a skin
gland
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The Mammary Gland
Secretory Tissues Glandular secreting tissue
Alveoli Duct system lined by
epithelial cells Lobules lobes clusters of
alveolar tissue supported by connective tissue
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The Mammary Gland
Alveolus basic secretory unit lined by
epithelial cells which synthesize and/or
secrete lipid - triglycerides free fatty
acids (FFA) protein - lactose minerals
vitamins - Ca, P, K Vits. A, B, C, D water
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Milk Synthesis
Milk synthesis is dependent on no. secreting
cells supply of milk precursor milking
frequency No. secreting cells is dependent
on genetics endocrine support for
mammogenesis
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Blood Components
Blood Flow (cattle)
Example What volume of blood would a 1400 lb.
Holstein pump per day?
1400 lb. Cow .9 liters/ heart stroke Volume/day
.9 x 70 strokes/min 63 liters/min 63
liters/min x 1440 min/day 90,720 liters/day
22,600 gal/day
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Blood Components
Blood Flow (cattle)
Volume of blood/ volume of milk synthesized
(this is an approximation actual ratio
is affected by stage of lactation, efficiency,
etc.)
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Steroid Hormones and Mammogenesis

• Estrogens
• follicle, placenta,
• Progesterone
• corpus luteum, placenta,
• Corticoids
• adrenal cortex

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Steroid Hormones and Mammogenesis
Estrogens (E2) (follicle, placenta) 1) 2) 3)
synergize with progesterone prolactin
to stimulate protein synthesis and duct growth
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Steroid Hormones and Mammogenesis
Progesterone (P4) (corpus luteum,
placenta) 1) stimulates lobulo-alveolar growth
retards milk synthesis 2) retards synthesis of
enzymes (a-lactalbumin) necessary for
lactogenesis in the prepartum mammary gland
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Lactogenesis Cortisol
Action of cortisol( from adrenal
cortex) (dexamethasone is synthetic cort.) 1)
synthesis stimulated by maternal, fetal
ACTH essential to lactogenesis (adrenalectomy
gt nolactogenesis) 2)
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Mammogenesis (Mammary Growth and Development)
Placental E2 luteal P4 duct development
lobulo-alveolar development suppression of milk
synthesis (P4 suppresses ?-lactalbumin lactose
synthesis
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Mammogenesis (Mammary Growth and Development)
Action of cortisol PRL increase PRL
receptor synthesis increase protein
transcription/translation cortisol is
permissive to action of PRL
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Lactogenesis (Milk Synthesis)

• How does P4 retard milk synthesis in the
  nonlactating mammary gland?
• Blocks glucocorticoid (cortisol) receptors
• Cortisol PRL stimulates synthesis of PRL
  receptors on mammary cells
• P4 blocks induction of PRL receptors
• Retards synthesis of a-lactalbumin, casein mRNA
• Retards casein, a-alactalbumin, lactose
  synthesis
• thus, retards milk synthesis

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Endocrine Glands Supporting Mammary Function

• Posterior pituitary (protein hormones)
• Oxytocin
• Synthesized in the hypothalmus
• Ttransferred to post. pit.
• Secreted into blood gt acts on myoepithelial cells
• Contraction of myoepithelial, smooth muscle

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Endocrine Glands Supporting Mammary Function
GH (STH, BST) increases milk
yield Action

• increases gluconeogenesis
• increases blood glucose
• increases efficiency of
• production (greater lbs. of
• milk/ lb. DMI)

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Endocrine Glands Supporting Mammary Function

• Pancreas (islets of Langerhans protein hormones)
• (responsive to blood glucose concentration)
• Glucagon (alpha cells)
• increases lipolysis
• increases glycogenolysis
• depresses cellular glucose uptake
• catabolic to adipose, muscle, liver tissue
• increases blood glucose concentration

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Lactogenesis
Lactogenesis initiation of milk synthesis
initiated in the E2/P4 primed mammary gland
when corpus luteum regresses P4 declines
cortisol increases PRL, GH increase these
circumstances occur at parturition
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