Embryogenesis And Neuralation

Question 1

What are the 2 blocks to polyspermy?

Answer 1

1. Oocyte PM Depolarization

2. Intracellular Ca2+ cortical reaction

Question 2

On what day does the follicle release the egg in a 28-day menstrual cycle?

Answer 2

Day 14 - follicular release

Question 3

Implantation occurs at Day ___ or Day 20 of the menstrual cycle. In this process, the _________ of the (OCM) outer cell mass secrete enzymes to “_______” from the zone pellucida. This new blastocyst implants into the endometrium and secretes _______ _____ ______ hormone for corpus luteum to continue secreting _______ and ________.

Answer 3

6,
Trophoblasts,
"Hatch",
Human chorionic gonadotrophin,
Estrogen and progesterone

Question 4

Trophoblasts

Definition, function, developing structures

Answer 4

Derived from OCM that implant into endometrium using enzymes and release hCG hormone. Later develop into fetal part of placenta.

Question 5

Epiblast

Definition, function, developing structures

Answer 5

Develop into amniotic cavity and intra-embryo 3 GERM LAYERS

Mesoderm, ectoderm and endoderm. A major (dorsal) component of the Bilaminar Disc in week 2.

Question 6

Hypoblast

Definition, function, developing structures

Answer 6

Develops into yolk sac and connecting stalk.It is also a site of hematopoeisis (vascularization too for the embryo). The most ventral part of the Bilaminar Disc.

Question 7

Ectoderm

Function and tissues

Answer 7

Communication with the environment.

Nervous system, epidermis, sensory receptors, sympatoadrenal glands.

Question 8

Mesoderm

Function and tissues

Answer 8

Supporting structures for the embryo.

Muscle, bone, cartilage, connective tissue.

Question 9

Endoderm

Function and tissues

Answer 9

Digest, breathe and secrete functions.

GI, lungs, trachea, most visceral glands.

Question 10

Towards what direction does the primitive streak form and at what day does gastrulation occur?

Answer 10

Caudal end (tail);
Day 16 - formation of 3 germ layers

Question 11

From most ventral (front) to dorsal (back) name the order of the 3 germ layers after the invagination process.

Answer 11

Endoderm (replaces hypoblast’s position)
Mesoderm (spread out within trilaminar disc)
Ectoderm (highest levels of BMP expressed; most exterior)

Question 12

What can be a cause for a teratoma and what type of cell can develop into the tissues within it?

Answer 12

A failure of the primitive streak to regress.
Pluripotent epiblast cells -> skin, muscle
*Can become malignant if not removed.

Question 13

Name the 2 areas with no mesoderm in the early embryo.

Answer 13

Sites of the embryo where the ectoderm and endoderm adhere tightly.

1. Buccopharyngeal membrane - foregut later forming the ORAL CAVITY
2. Cloacal membrane - hindgut that later forms the ANAL CANAL

Question 14

What is the maternal part of the placenta?

What embryo cell derivative gives rise to fetal placenta?

Answer 14

Decided basilis;

Trophoblasts

Question 15

What cell type in the bilaminar disc gives rise to the connecting stalk that ultimately becomes the umbilical cord?

Answer 15

Hypoblast