Gut barrier function and development in neonates

Question 1

3 layers of fetal membranes

Answer 1

1.endothelium
2.connective tissue (chorioallantoic mesoderm)
3.chorionic epithelium (out layer of fetal membranes)

Question 2

3 potential layers of maternal membrane

Answer 2

1.endothelium
2.maternal connective tissue
3.maternal endothelium cells

Question 3

Layers of cow,horse, pigs

Answer 3

-all layers present
=epitheliochorial

Question 4

Layers of dog and cat

Answer 4

-no endometrial epithelial cells or maternal connective tissue

Question 5

Layers in humans, rodents

Answer 5

-no maternal endothelial, maternal connective tissue, and endometrial epithelial cells

Question 6

Passage of macromolecules

Answer 6

-immature enterocytes (fetal) possess high endocytic capacity for macromolecular passage
-ends at gut closure (timing varies among species)

Question 7

Ungulate macromolecule passage

Answer 7

-placenta is effective barrier
-born agammaglobulinemic
-extensive macromolecular transmission including colostral antibodies during the first days of life
-non selective, endocytosis

Question 8

Ungulate barrier closure

Answer 8

-closure in duodenum, jejunum is 1-2 days
-distal small intestine at 2-3 weeks

Question 9

Carnivore macromolecule passage

Answer 9

-some maternal IgG transmitted over placenta
-main macromolecular transfer from colostrum similar to ungulates

Question 10

Primate macromolecular passage

Answer 10

-extensive, selective, transfer across placenta
-receptor mediated binding of IgG to FcRn receptors
-especially during late gestation

Question 11

Rodents macromolecular passage

Answer 11

-species dependent
>(ex. guinea pigs) receive IgG in utero
>rats and mice limited in utero transfer
-post natal expression of FcRn receptors that bind IgG as well as other milk proteins

Question 12

Macropinocytosis

Answer 12

-no need for receptors
-occurs in ungulates, carnivores, and primates

Question 13

Timing of intestinal barrier closure in puppies

Answer 13

-IgG absorption level is much higher if given colostrum immediately after birth
-puppies given colostrum 24hrs after birth, IgG absorption very low

Question 14

Gut closure age in rodents

Answer 14

3 weeks

Question 15

Gut closure age in ungulates and carnivores

Answer 15

1-2 days

Question 16

Gut closure age in primates

Answer 16

22 weeks