Pregnancy

Question 1

Lactogenesis vs Milk let-down response

Answer 1

Lactogenesis: milk production

Milk letdown response: release of stored milk

Question 2

Milk let down / ejection reflex

Answer 2

1. Baby suckling sends impulses from the nerves of the nipple to the hypothalamus
2. Anterior pitutiary releases prolactin: secrete milk into alveoli
3. Posterior pituitary releases oxytocin: causes the myoepithelial cells to squeeze alveoli

Question 3

Lactational amenorrhea

Answer 3

prolactin inhibits GnRH –> amenorrhea

This is why your period stops during pregnancy - to stop ovarian follicle development

Question 4

Regression of mammary gland after lactation

Answer 4

Resorption of glandular tissue & reestablishment of c.t. and adipose tissue

Question 5

How does the mamary gland change after menopause?

Answer 5

Connective tissue decreases (less cellular, more fibrous)

Involution of ducts & secretory units

Question 6

Things leading up to implantation

Answer 6

Fertilization in the ampulla > 2,4, 8, cell stage > blastocyst rolls along the endometrium> implantation into the endometrium

Question 7

When does implantation occur?

What important things happen during implantation?

Answer 7

Occurs during the secretory phase (days 21-24 of cycle)

• Syncytiotrophoblasts secrete hCG to rescue and maintain the corpus luteum
• Decidual reaction: hypetrophy of endometrial stromal cells

Question 8

Why do we need so much progesterone and estrogen during pregnancy?

Answer 8

To maintain the thickness of the endometrial lining

Question 9

Answer 9

25 days

We’re at day 40. Conception is day 15. Thus, conception occured 40-15 = 25 days ago.

Question 10

Decidual reaction

Answer 10

the continued produciton of progesterone & estrogen cause endometrial stromal cells to hypertrophy and fill with glycogen & lipid

–> fibroblasts look more round

Question 11

Functions of decidua

Answer 11

• Source of nutrients for embryo until vascular connections between mother and embryo are developed
• Barrier to further invasion of the uterine wall by the mebryo
• Endocrine function: prolactin, relaxin, and prostaglandins act on uterine muscle, cervix, and embryo

Question 12

Relaxin

What produces it?

What is it stimulated by?

What are its funcitons?

Answer 12

• Produced by decidua, corpus luteum of pregnancy, and placenta
• Stimulated by hCG
• Fxns:
  
  • Early pregnancy: suppress myometrial contractions
  • Late pregnancy: soften cervix in preparation for parturition

Question 13

Prolactin

What makes it?

Function?

Answer 13

Major source: maternal pituitary and decidua

Function: depress immune response to fetus

Question 14

Prostaglandins

what makes it

function

Answer 14

Decidua

In late pregnancy, it contracts uterine smooth muscle and softens the cervix.

Question 15

What are the blue arrows pointing at?

Answer 15

Decidual cells / Stroma cells

Question 16

What changes do we see in the endometrium and myometrium in the pregnant uterus?

Answer 16

Decidual reaction: endometrial stroma becomes decidua

Myometrium: hyperplasia & hypertrophy

Question 17

Tissue layers of the blastocyst (inner to outer)

Answer 17

• Cytotrophoblast (inner)
• Synctiotrophoblast (outer)

Question 18

Describe the trophoblast

Answer 18

Peripheral cells of the blastocyst that attach the fertilized ovum to the uterine wall and contribute to the placenta

Cytotrophoblast (inner): mitotically active trophoblast-producing cells that fuse with the syncytiotrophoblast

Syncytiotrophoblast (outer): not mitotically active; multinucleate cytoplasmic mass invades the epithelium and underlying stroma of the endometrium

Question 19

Syncytium

Answer 19

a multinucleate cellular mass produced by the fusing of cells.

Question 20

Functions of the placenta

Answer 20

• Endocrine
  
  • Synthesizes & secretes hormones for maternal & fetal metabolism
  • Independent; not subject to regulation by maternal or fetal signals!
• Fetal gut supplying nutrients
• Fetal lung exchanging gases
• Fetal kidney eliminating waste products & regulating fluid volume

Question 21

Describe the components of placenta

Answer 21

• Fetal portion - chorion
  
  • Chorionic plate
  • Chorionic villae
  • Cytotrophoblastic shell
• Maternal portion - decidual basalis
  
  • Basal plate
  • Placenta septa

Question 22

What is the blue bar?

Answer 22

The chorion: contains the secondary villus, the cytotrophoblast, and the syncytio trophoblast

Question 23

What is the blue line pointing at?

Answer 23

Cytotrophoblastic shell

Question 24

Establishing placental circulation

Answer 24

The chorion (fetal criculation) sends out villi into the placenta, wher eit will capture maternal blood in the decidual basalis

Question 25

Where is the maternal blood vs the fetal blood?

Answer 25

This is chorionic villi The fetal blood supply would be within the villi (BV) The maternal blood supply would be in the interstitial space (IS)

Question 26

Histologically how do cytotrophoblasts look diff from syncytiotrophoblast?

Answer 26

Syncytiotrophoblasts look like packs of nuclei Cytotrophoblasts have one fat nucleus

Question 27

Free vs anchoring villi

Answer 27

Free villi dont connect to the decidual basalis Anchoring villi do

Question 28

Describe the **placental barrier** that blood, gas, and nutrients have to cross to get to the fetus

Answer 28

**Syncytiotrophoblast** **Cytotrophoblast** Connective tissue (**extraembryonic mesenchyme)** **Fetal endothelial cell** of blood vessel

Question 29

What crosses the placental barrier?

Answer 29

* Exchange of **gases & nutrients (glucose, aa, proteins)** * **Transferrin** (iron to fetus) * **Steroid hormones** * Fetus eliminates C**O₂ and waste** * Maternal **antibodies (esp igG)** provides passive immunity to the newborn * **Alcohol, drugs, some viruses** (birth defects)

Question 30

The placenta secretes numerous **steroid & protein** hormones that affect **maternal AND fetal** metabolism How is it regulated?

Answer 30

Independent! not subject to regulation by maternal or fetal signals

Question 31

Answer 31

**Urinary estriol & serum hCG** ## Footnote **Fetus is responsible for estriol** **hCG is only ever produced by the placenta by syncytiotrophoblast only** (whereas, progesterone can come from corpus luteum of pregnancy AND placenta).

Question 32

Cytotrophoblast hormones

Answer 32

​**IGF-I and IGF-II** to stimulate proliferation/differentiation **GnRH**, **CRH**, **TRH**, and **somatostatin** to act on the syncytiotrophoblast

Question 33

Syncytiotrophoblast hormones

Answer 33

* **hCG**, human chorionic **ACTH**, human placental **GH**, and human chorionic **thyrotropin** * **Progesterone** * **Estradiol** * **Inhibin A**: suppress mother's FSH * **Human chorionic somatomammotropin (hCS)/hPL**: shunts nutritional substrates to fetus

Question 34

Funcitons of progesterone secretion from placenta

Answer 34

* Inhibits maternal immune responses * provide precursors to fetal adrenal glands * quiets uterine contractions * stimulates mammary gland development

Question 35

Function of estrogens released from sycytiotrophoblast

Answer 35

* Stimulates growth of uterine smooth muscle * Stimulates mammary gladn development ## Footnote *Can't synthesize androgen precursors for estradiol synthesis; must use fetal adrenal glands*

Question 36

Function of **human chorionic somatommaotropin (hCS) aka hPL**

Answer 36

Shunt nutritional substrates to fetus

Question 37

Where do androgen precursors for estradiol synthesis come from in placenta?

Answer 37

androgen precursors come from the **fetal androgen gland**

Question 38

describe the process of **placental steroidogenesis**

Answer 38

1. Mother sends cholesterol to the placenta 1. Make **pregnenolone** to be sent to the fetus 2. Make **progesterone** 2. **​**Fetus makes **DHEA** from pregnenolone and then creates the androgen precursor to be sent back to the placenta for it to then make **estriol**

Question 39

**Progesterone & Estrogen synthesis** Which occurs **independently of the fetus**? Which can be used to **assess fetal health**?

Answer 39

Progesterone synthesis tells us about placental health

Question 40

How long does hCG maintain estrogen & progesterone secretion until?

Answer 40

Until the end of the 1st trimester, then placenta takes over

Question 41

High levels of s**ex steroids from the placenta** suppress __ to prevent \_\_.

Answer 41

the hypothesis/pituitary axis to prevent ovulation

Question 42

Prolactin's action on the mammary gland during prengancy is blocked by \_\_\_\_. What causes the lactogenic effect to start?

Answer 42

Blocked by E & P during pregnancy Extrusion of placenta during birth --\> drop in E & P --\> lactogenic effect commences

Question 43

Review of pregnancy hormone levels

Answer 43