Embryology (Ch 3) Flashcards Preview

Anatomy > Embryology (Ch 3) > Flashcards

Flashcards in Embryology (Ch 3) Deck (19):
1

What are the three stages of development?

1. Pre-Embryonic Development (weeks 1-2)
2. Embryonic Development (weeks 3-8)
3. Fetal Development (weeks 9-birth)

2

Pre-Embryonic Development

--> first two weeks after fertilization
1. fertilization (zygote)
2. cleavage: zygote (one cell) -> morula (16 cells)
3. morula takes up fluid --> blastocyst (hollow ball w/two cell types)
4. blastocyst implants into uterine wall
5. blastocyst differentiates into two laters (bilaminar disc)

3

cleavage

series of mitotic divisions that causes zygote to break into 16 cells called the morula

4

blastocyst

hollow ball of two cell types
1. Inner Cell Mass: develops into embryo
2. Outer Ring of cells (trophoblast): develops into placenta

5

bilaminar disc

two layers of the blastocyst

6

Embryonic Development

-->weeks 3-8
-gastrulation (bilaminar disc-->trilaminar disc)
-blastocyst cells form the 3 germ layers
-primitive streak (raised groove) appears onto of embryo
-epiblast cells begin to migrate inward at primitive streak --> become endoderm

7

What is gastrulation?

--> process by which the cells of the epiblast migrate and form the three primary germ layers
(bilaminar --> trilaminar)
1. formation of primitive streak
2. cells travel up streak forming three layers

8

What are the three germ layers?

1. Ectoderm (outer)
2. Mesoderm (middle)
3. Endoderm (inner)

9

What are parts of the ectoderm?

epidermis, nervous tissue, pituitary gland, tooth enamel

10

What are parts of the mesoderm?

notochord, heart, kidney, skeleton, muscles, dermis

11

What are parts of the endoderm?

linings of digestive/respiratory tract, liver, pancreas, thyroid

12

What are the subdivisions of the mesoderm?

1. Notochord: central axis of embryo in adult
2. Lateral Plate Mesoderm
3. Intermediate Mesoderm
4. Paraxial Mesoderm

13

Somites and their subdivisions

block-like early body segments formed from paraxial mesoderm (become axial skeleton, muscle, cartilage, dermis, and connective tissue)
1. Sclerotome: become vertebrae and ribs
2. Myotome: becomes limb/trunk muscles
3. Dermatome: becomes dermis layer of skin

14

What is the notochord?

cylindrical mass of mesoderm becomes central axis in adults --> signals ectoderm to form neural tube (brain/spinal cord) (aka NEURULATION)

15

Fetal Development

--> week 9 to birth
-period of rapid growth/maturation of organs

16

zygote

fertilized egg

17

embryo

when the three germ layers have been formed

18

fetus

all organs present in some rudimentary form

19

Neurulation

formation of the neural tube (brain/spinal cord)
-notochord signals ectoderm to form neural tissue (induction) --> neural tube