Definitions in Embryology

Question 1

Define Gametogenesis

Answer 1

Formation of gametes (sperm and eggs)

Question 2

Define Cleavage

Answer 2

Cell division of the zygote by mitosis, the cells formed are identical diploid cells but half the size of the parent cell. The cleavage leads to the formation of the morula and then the blastocyst

Question 3

Define Gastrulation

Answer 3

Formation of the embryonic disc

Question 4

Define Embryonic disc

Answer 4

Ectoderm, mesoderm, endoderm- the primary three germ layers of embryonic tissue

Question 5

Define Germ layers

Answer 5

Ectoderm, endoderm, mesoderm

Question 6

Define Morula

Answer 6

Tight cluster of diploid cells formed by cleavage, it forms by day 2-3 post fertilisation

Question 7

Define Blastomere

Answer 7

A cell formed by cleavage I.e. the cells that make up the morula and blastocyst

Question 8

Define Primordial germ cells

Answer 8

Formed by 4 weeks gestation- these are the cells that will eventually develop into gametes

Question 9

Define zona pellucida

Answer 9

A glycoprotein layer surrounding the oocyte

Question 10

Where does the blastocyst hatch from?

Answer 10

The zona pellucida

Question 11

Define corona radiata

Answer 11

The innermost layer of cells that surrounds the zona pellucida that surrounds the oocyte

Question 12

Define cumulus oophorus

Answer 12

A layer of granulosa cells that surround the zona pellucida and oocyte. It contains the corona radiata at it’s innermost layer of cells

Question 13

Define perivitelline space

Answer 13

Space between the oocyte and zona pellucida. it is where the secondary body lodges after meiosis