Lecture 2 embryology

Question 1

Embryology

Answer 1

study of the origin and development of an individual person or organism

Question 2

Prenatal period

Answer 2

the time between conception and birth
has two periods: embryonic period, and the fetal period

Question 3

Embryonic period

Answer 3

First 8 weeks
by the end of this period all major organs are in place

Question 4

Fetal period

Answer 4

8-30 weeks
the organs of the fetus grow larger and more complex

Question 5

Ectoderm

Answer 5

The outermost layer of cells or tissue in early development. The parts derived from this, will form the epidermis and nerve tissue

Question 6

Endoderm

Answer 6

the inner most layer of cells or tissue in early development. The parts derived from this, will form the primitive gut, digestive tract, liver, pancreas, and part of the lungs.

Question 7

mesoderm

Answer 7

The middle layer of cells or tissue in early development. The parts derived from this, will form structure including the skeletal system, muscular system, and notochord. Divides later to form many important organ systems.

Question 8

Fertilization

Answer 8

Fusion of the sperm and egg nuclei
Generally occurs in the lateral third of the uterine tube

Question 9

Zygote

Answer 9

fertilized oocyte

Question 10

Cleavage

Answer 10

rapid cell divisions without intervening growth periods. begins with a fertilized ovum and produces blastocyst

Question 11

Morula

Answer 11

solid cluster of cells
after 72 hrs there’s about 12-16 cells

Question 12

blastocyst

Answer 12

early embryonic development
a hollow ball of cells and the product of cleavage

Question 13

Blastocyst stage

Answer 13

Inner cell mass: accumulation of cells in the blastocyst
Trophoblast: the external layer of cells in the blastocyst. forms placenta
Implantation: takes about a week, trophoblast erodes

Question 14

Day 1

Answer 14

fertilization occurs. the egg is called a zygote

Question 15

Day 2-4 cell stage

Answer 15

zygote continues to divide as it travels to the uterus, this is called cleavage

Question 16

Day 3

Answer 16

the cleavage generates a cluster of cells called a morula

Question 17

day 4-6

Answer 17

morula enters the uterus and is called a blastocyst. On day 6 blastocyst will burrow into the uterus

Question 18

day 7

Answer 18

implanting the blastocyst

Question 19

Inner cell mass

Answer 19

divides into epiblast and hypoblast
during gastrulation, it’ll become into a trilaminar disc

Question 20

epiblast

Answer 20

The outermost layer of an embryo before it differentiates into the ectoderm and mesoderm

Question 21

hypoblast

Answer 21

The innermost layer of an embryo before is gives rise to the yolk sac, and will contribute to the endoderm

Question 22

gastrulation

Answer 22

An early developmental process in which the embryo transforms from a 1 dimensional layer of cells (epithelial) and reorganizes into a multilayers and multidimensional structure referred to as the gastrula

Question 23

bilaminar disc

Answer 23

Refers to the two-layered structure of the epiblast and hypoblast

Question 24

amniotic sac

Answer 24

The fluid-filled sac that contains and protects the embryo and eventually the fetus in the womb.

Question 25

primitive streak

Answer 25

An elongated band of cells that forms along the axis of a developing embryo early in gastrulation

Question 26

epiblast

Answer 26

The outermost layer of an embryo before it differentiates into the ectoderm and mesoderm.

Question 27

primitive node

Answer 27

An area through which migrating cells are channeled into a rodlike structure of mesenchymal cells

Question 28

notochord

Answer 28

cells that gather and form a cartilaginous skeletal rod

Question 29

neurulation

Answer 29

folding process of the embryo

Question 30

Neural plate

Answer 30

induces the overlying ectoderm (at the midline) to thicken and form an elongated structure called the neural plate. This will give rise to the CNS, brain, and spinal cord

Question 31

neural Groove

Answer 31

Formed by infolding neural fold cells (from endoderm), this groove closes the neural tube which becomes separated from the overlying ectoderm. This closure is very important (folic acid)