Early Human Development

Question 1

Totipotent

Answer 1

Able to generate all cell types, embryonic and extraembryonic (placenta)

Question 2

Pluripotent

Answer 2

Able to generate cell types from all embryonic germ layers; ectoderm, mesoderm, endoderm

Question 3

Multipotent

Answer 3

Able to generate all cell types within a germ layer

Ex: multipotent

Question 4

Bipotential

Answer 4

Able to generate 2 cell types

Ex: neural stem cell (neurons and glia)

Question 5

Unipotent

Answer 5

Generate only 1 cell type
Committed/cell fate restricted progenitors
Ex: oogonia or spermatogonia

Question 6

Epithelium

Answer 6

Tightly joined sheet of cell, containing a basement membrane and organized polarity
Non-motile cells
Adherent cells
Closely knit, form a barrier

Question 7

Mesenchyme

Answer 7

Loosely associated cells, having multiple processes

Usually motile

Question 8

Ectoderm

Answer 8

Outside layer
An epithelium
Gives rise to skin and the nervous system

Question 9

Mesoderm

Answer 9

Middle layer
Mesenchym
Gives rise or contributes to most of the internal organs, vasculature, blood, lymphatics

Question 10

Endoderm

Answer 10

Internal epithelial layer
Gives rise to digestive system (esophagus, stomach, gut) and associated organs (bile duct, gallbladder, parts of pancreas)

Question 11

Neural crest cells

Answer 11

Multipotent cell type
Arises from the edge of the dorsal neural tube
Migrates extensively to give rise to a wide variety of tissues, including much of the craniofacial skeletal structures, parts of the inner ear, peripheral and sympathetic nerves, Schwann cells, pigment cells

Question 12

Primordial germ cells

Answer 12

Pluripotent cells set aside during embryology that migrate to populate the gonads during development
In males, give rise to spermatogonia. In females, give rise to oocytes

Question 13

4 steps in fertilization

Answer 13

1. Oocyte penetration
2. Acrosomal reaction
3. Male and female pronuclei
4. Pronuclear fusion

Question 14

Gastrulation

Answer 14

Formation of the embryonic germ layers

Question 15

Meiosis

Answer 15

2 step division process by which sperm and eggs are produced

Question 16

Acrosome

Answer 16

Sac of enzymes that help digest the lipoprotein coat on the egg

Question 17

Zona pellucida

Answer 17

Lipoprotein coat on the oocyte

Question 18

4 Phases of fertilization

Answer 18

1. Capacitation of the reproductive system
2. Acrosome reaction
3. Corona and Zona penetration
4. Cytoplasm entry

Question 19

Where does fertilization usually occur?

Answer 19

In the ampulla of the uterine tube

Question 20

What is the importance of compaction?

Answer 20

It starts the specialization of cells
The inside cells are different from the outside cells
Outside ones become the trophoblast, inner ones become fetus
Associated with the transition from maternal influences on development to the activation of the zygotic genome

Question 21

What does progesterone do?

Answer 21

Tells the site of implantation to vascularize

Question 22

Prechordal plate

Answer 22

Beginnings of the system that induces the NS

Question 23

Where is the amniotic cavity located?

Answer 23

At the pole where the embryo is connected to the mother

Question 24

Syncytiotrophoblast

Answer 24

So much proliferation that they dont even form cell boundaries
Invade into the wall
Form sinusoids
Multiple nuclei sharing a cytoplasm
Gets maternal blood to embryo eventually

Question 25

Embryoblast splits into 2 layers….

Answer 25

Epiblast (embryo proper)

Hypoblast (or primitive endoderm)

Question 26

Bilaminar blastoderm/embryonic disc

Answer 26

Remaining epiblast + hypoblast

Question 27

Decidual cells

Answer 27

When the embryo implants, adjacent cells of the endometrial stroma respond to its presence and progesterone and differentiate into metabolically active SECRETORY CELLS

Question 28

HCG is secreted by the ___ and does what

Answer 28

Secreted by the trophoblast

It supports the corpus luteum to maintain the supply of progesterone