Dh-Ohe: Deha Ch 3-Overview Of Prenatal Development

Front 1

When does preimplantation occur?

Back 1

Preimplantation = "fertilization"

The 1st week

Front 2

What is a zygote?

Back 2

Zygote:

The union of "egg"+ "sperm"

Front 3

When does the Embryonic Period occur?

Back 3

Embryonic Period:

2nd -8th week

Front 4

When does the Fetal Period occur?

Back 4

Fetal Period:

third to ninth month

* after the first trimester

Front 5

The first trimester is composed of which two periods?

Back 5

First Trimester:

(1) Preimplantation
(2) Embryonic period

Front 6

How many chromosomes does the egg and sperm each have?

Back 6

Egg/Sperm:

haploid number = 23 chromosomes

hap ="single"

Front 7

How many chromosomes does the zygote have?

Back 7

Zygote:

diploid number = 46

di = "double"

Front 8

Somatic Cells

Back 8

Somatic Cells:

all other cells other that have 46 chromosomes

NOT egg and sperm

Front 9

Gametes

Back 9

Gametes:

egg and sperm

Front 10

Why must gametes only contain the haploid number of 23 chromosomes?

Back 10

IF the egg and sperm contained 46 chromosomes each the zygote would have 92 chromosomes!!!

a LOT of genetic problems can occur just having 1 extra chromosome

Front 11

Meiosis

Back 11

Meiosis:

(1) The process by which chromosomes are separated during the formation of SEX CELLS
(2) their number reduced from 46 - the haploid number (23)

Front 12

What is the purpose of Meiosis

Back 12

PURPOSE of Meiosis:

The recombination (mixing) of chromosomes for
(1) SEXUAL REPRODUCTION
(2) GENETIC DIVERSITY

Front 13

Meiosis undergoes how many cell divisions? How many daughter cells are produced?

Back 13

Meiosis:

(1) has 2 cell divisions
(2) produces 4 daughter cells (each w/haploid (23) chromosomes)

Front 14

Mitosis undergoes how many cell divisions? How many daughter cells are produced?

Back 14

Mitosis:

(1) has 1 cell division
(2) produces 2 daughter cells (each with diploid (46) chromosomes

Front 15

What is the purpose of Mitosis?

Back 15

Purpose of Mitosis:

(1) Cellular Reproduction
(2) For normal growth and repair
(3) want new cells--all the same

Front 16

Where does fertilization occur?

Back 16

Fertilization occurs:

When in the fallopian tube

Front 17

How does the Blastocyst form?

Back 17

Blastocyst Formation:

(1) AFTER fertilization
(2) when the zygote undergoes MITOSIS and divides
(3) contains 46 chromosomes

Front 18

What is the zygote?

Back 18

Zygote:

(1) it's essentually an egg (ovum)
(2) sperm come in--the it's destroyed

Front 19

Where does implantation occur and when?

Back 19

Implantation occurs:

(1) in the ENDOMETRIUM--
(2) when the blastocyst travels to the uterus
(3) 6th day

Front 20

What attaches the blastocyst to the endometrium and develops into the placenta?

Back 20

Trophoblast Layer (outer)

Front 21

What develops into the embryo?

Back 21

Embryoblast Layer (inner layer)

Front 22

What occurs during the 2nd week of prenatal development as the result of continued cell divisions?

Back 22

Bilaminar Embryonic Disk Formation

After Embryoblast separates from Trophoblast layer
***Embryoblast flattens into an EMBRYONIC DISK (red section) made of 2 layers
(1) Epiblast Layer "TOP"( facing the amniotic cavity)
(2) Hypoblast layer "UNDER" (facing the yolk sac)

Front 23

Embryogenesis

Back 23

Embryogenesis:

arrangement of blastomeres into three primary germ layers in the embryoblast

Front 24

What are the (2) layers that make up the Bilaminar Embryonic Disk?

Back 24

Embryonic Disk (red section-middle)

(1) Epiblast layer (facing the amniotic cavity)

(2) Hypoblast layer (facing the yolk sac)

Front 25

Identify the epiblast and hypoblast layers. What does layers do they turn into?

Back 25

Epiblast (blue)
(1) ectoderm (2) mesoderm (3) neuroectoderm

Hypoblast (yellow)
(1) endoderm

Front 26

What occurs during Trilaminar Disk Formation and when?

Back 26

Trilaminar Disk Formation: 2nd week of prenatal dev,

The cells from the epiblast layer migrate along the primitive streak and SEPARATE the epiblast layer (ectoderm) from hypoblast layer (endoderm)

Front 27

What is the origin of the mesoderm?

Back 27

Mesoderm forms:

From the migrating EPIBLAST cells

***makes the embryonic disk TRILAMINAR

Front 28

What is the Primitive Streak and what is it's significance?

Back 28

Primitive Streak:
thickened cell layer that forms along the midline of the epiblast

SIGNIFICANCE: makes embryo BILATERALLY SYMMETRICAL
(1) defines left/ right
(2) dorsal / ventral sides
(3 defines cephalic end / caudal end

Front 29

What is mesenchyme?

Back 29

Mesenchyme:

are the migratory cells that locate in the middle b/w the epiblast and hypoblast layers that turns into EMBRYONIC CONNECTIVE TISSUE

Front 30

What does mesenchyme produce?

Back 30

Mesenchyme Produces:

some cells make ***MESODERM

MAKES TISSUE FORMING CELLS-
(1) fibroblasts
(2) chondroblasts
(3) osteoblasts

Front 31

Discuss the early formation of the "central nervous system" and when does it occur?

Back 31

CNS Formation: Spinal cord, brain

WHEN: (later part 3rd wk)
(1) some cells differentiate from the ectoderm (NEUROECTODERM)
(2) and localize at the NEURAL PLATE
(3) Plate thickens-forms NEURAL GROOVE
(4) Groove deepens-form NEURAL FOLDS
(5) Folds form NEURAL TUBE (aka Spinal Cord)

Front 32

What are the "neural crest cells" produced by

Back 32

Neural Crest Cell:

PRODUCED BY: Neural Ectoderm

They migrate from crests of NEURAL FOLDS and disperse within Mesenchyme

Front 33

How are "neural crest cells", related to the development of structures in the head and neck region?

Back 33

Neural Crest cells- FACE & NECK

(aka "4th embryonic layer")

INVOLVED IN FORMATION OF:
(1) Nervous System
(2) Connective Tissue
(3) certain DENTAL TISSUES****

Front 34

What are "somites"

Back 34

SOMITES:

the 38 PAIRED BLOCKS of mesoderm that form on each side of the dev. midline of CNS in embryonic disk

Hint 34

DEHA Ch 3 p 35

Front 35

How are "somites" related to the development of structures in embryo?

Back 35

SOMITES:

Give rise to -
(1) Axial skeleton (Skull, spine, pelvis)
(2) muscles
(3) dermis of skin

Hint 35

DEHA Ch 3 p 35

Front 36

What happens during the fourth week of prenatal development?

Back 36

4th week of Prenatal dev.

EMBRYONIC FOLDING

Hint 36

DEHA Ch 3 p 35

Front 37

What is Embryonic Folding?

Back 37

Embryonic Folding: (occurs 4th week)

(1) Trilaminar Disk forms into EMBRYO,
(2) estab the human axis
(3) placement of tissues in their proper positions

Hint 37

DEHA Ch 3 p 35

Front 38

What is the location of the three germ layers during Embryonic Folding?

Back 38

Germ layers (Embryonic Folding)

LOCATION
(1) Ectoderm = outside/top (BLUE) - Brain
(2) Mesoderm = middle (PINK) - Heart
(3) Endoderm = inside/bottom (YELLOW) - Gut

Hint 38

DEHA Ch 3 p 35-36

Front 39

Where does Ectoderm originate from and what does it produce?

Back 39

Origin ECTODERM: Epiblast layer

FORMS (think "outer")
(1) Connective Tissue
***SKIN = EPIdermis (epi= outer)
***MOUTH = muscosa
(2) Nervous system
(3) eyes, ears, nose
(4) Neural Crest cells
(5) cutaneous glands

Hint 39

DEHA Ch 3, p.33 (Table 3.4)

Front 40

Where does Mesoderm originate from and what does it produce?

Back 40

Origin MESODERM: (Migrating Epiblast layer)

FORMS (think "Middle")
(1) Connective Tissue
***SKIN = Dermis
***MOUTH = SUBmucosa
(2) Muscle (Ex: Cardiac Muscle-Heart)
(3) Bone
(4) blood cells
(5) Reproductive/Excretory organs

Hint 40

DEHA Ch 3, p.33 (Table 3.4)

Front 41

Where does Endoderm originatefrom and what does it produce?

Back 41

Origin ENDODERM: Hypoblast layer

FORMS (Think "inner")
(1) LININGS (Resp. and Digestive sys)
(2) Liver and Pancreatic cells

Hint 41

DEHA Ch 3, p.33 (Table 3.4)

Front 42

Describe the oral complications associated with ectodermal dysplasia.

Back 42

Ectodermal Dysplasia

the ABNORMAL dev. of 1 or more ECTODERMAL STRUCTURES

(1) teeth (2) skin (3) hair (4) nails (5) eyes (6) facial structures (7) glands

Ex: Anodontia (missing teeth)

Hint 42

DEHA Ch 3, p.35

Front 43

What are the landmarks of the embryo present during the fourth week?

Back 43

4th week Landmarks:

(1) Developing HEART
(2) Develoing BRAIN
(3) Developing DIGESTIVE SYSTEM

Hint 43

DEHA Ch 3, p.36

Front 44

Describe the development of the Digestive Tract and when does it occur?

Back 44

Digestive Tract Dev. (begins 4th week)

From ENDODERMAL Tube
(1) Foregut = ant. PHARYNX
(2) Midgut & Hindgut = post. PHARYNX

Hint 44

DEHA Ch 3 p.36

Front 45

Define the fetal period of prenatal development and what important milestone occurs?

Back 45

FETAL PERIOD (9th week-birth)

it is the period of MATURATION of the existing structures as the embryo enlarges and becomes a FETUS.

MILESTONE: 4th month
(1) Fetal Heart beat & mvmt felt

Hint 45

DEHA Ch 3 p.36

Front 46

Teratogenesis

Back 46

Teratogenesis

the production of congenital malformations in the dev. EMBRYO

Hint 46

CH 3 Powerpoint

Front 47

Teratogens

Back 47

Teratogens

Environmental agents that can cause congenital malformations in the dev. embryo

Ex: Rubella virus, Thalidomide, Tetracycline

Hint 47

Ch 3 Powerpoint