AGR 506 Puerperium and Lactation

What is Puerperium? What does it allow?

The period after parturition when reproductive tract returns to nonpregnant condition

Allows female to become pregnant again

When does Puerperium start and end?

Begins immediately after parturition

Ends when reproductive function is restored

(Length is species dependent)

What are the four major events of Puerperium?

1. Myometrial contractions and expulsion of lochia

2. Endometrial repair

3. Resumption of ovarian function

4. Elimination of bacterial contamination of the reproductive tract

What is Lactation?

Synthesis, secretion and removal of milk from the mammary gland

What are Mammary glands?

Sophisticated sweat glands

When do changes in the mammary gland occur postnatally?

-Between birth and puberty

-Between puberty and pregnancy

-During pregnancy

-During lactation

-During involution

What is Uterine Involution?

Myometrial contractions that cause reduction in uterine size and volume

What is the purpose of uterine involution?

-Facilitate discharge of fluids and tissue debris from uterus

-Compress uterine vasculature and help minimize possibility of hemorrhage

-Reduce overall size of uterus

What does Uterine involution cause?

-Decreased uterine size

-Decreased uterine volume

-Expulsion of lochina

-Endometrial repair

What does caruncle repair require?

Vasoconstriction, necrosis and sloughing of tissue

followed by growth of surface epithelium

After separation of fetal cotyledons from the maternal caruncle during caruncle repair what are the 5 steps that follow?

1. Vasoconstriction takes place in the stalk of the maternal caruncle

2. Necrosis follows

3. Some blood is released from stalk and produces a blood-tinged fluid

4. Chunks of caruncle will detach and leave blood vessels exposed

5. Repair is initiated and caruncle will be coved with endometrial epithelium again

At the same time caruncles are being repaired, what else is being repaired?

Intercaruncular endometrial surfaces

What is postpartum bacterial contamination most common in?

Domestic animals

What are the predisposing factors to postpartum bacterial contamination?

-Retained fetal membranes

-Dystocia

-Delay in lochial expulsion

What are the results of postpartum bacterial contamination?

-Prolong uterine involution

-Prolong puerperium

-Delay subsequent pregnancies

How do mammary glands change with Estradiol?

Ducts begin to branch and their diameter increases

How do mammary glands change with Progesterone?

Terminal portions of each branch begin to form initial portions of alvoeli

How do mammary glands change with Prolactin and growth hormone?

Complete and rapid duct development

When does final mammary gland development occur?

Pregnancy

What hormones are important in allowing mammary epithelium to synthesize milk?

-Prolactin

-Adrenal Cortical

-Placental Lactogen

Why is colostrum so important?

Contains immunoglobulins (antibodies) for passive immunity critical for neonatal survival

Ruminants with a _______ placenta cannot transfer what in in-utero?

Epitheliochorial placenta

Immunoglobulins

What does milk contain?

hormones and growth factors

How does Milk ejection work?

Milk transfers from mammary alveoli into the ducts, then cesterns and into teat or nipples where it can be removed by suckling neonate

What does Milk Ejection require?

-Sensory activation (auditory, tactile, and visual)

-Neural activation og hypothalamus

-Oxytocin release into blood

-Contraction of myoepithelial cells

-Mechanical transfer of milk from alveoli into ducts and finally into the teat/nipple