How does the blastula relate to clevage?

The blastula stage signals the end of the period in embryogenesis known as cleavage.

Blastula anotomical description

The blastula can be defined in anatomical terms as a hollow stage in the embryo’s development, with a cavity (the blastocoele), surrounded by an epithelial cellular layer called the blastoderm.

***The teleosts (bony Fishes) have a blastoderm that does not surround the “Blastocoele”

Blastula Formation

Blastula (single layer cell) Gastrula (Three cell layers- endoderm, mesoderm, ectoderm)

Gastrula

1. Rearrangement of cells of the embryo via morphogenetic movements
2. Slower mitotic rate
3. No significant growth
4. metabolic change (increased oxidation)
5. Embryonic nuclei become active
6. Qualitative change in protein population

Gastrula 6 Primairy changes

1. Rearrangement of cells of the embryo via morphogenetic movements
2. Slower mitotic rate
3. No significant growth
4. metabolic change (increased oxidation)
5. Embryonic nuclei become active
6. Qualitative change in protein population

Real

New

Mice

Eat

Qualil

Frog Fate Map layers

Frog fate map external

Bony Fish fate map

Primary Organizers

1. Micromeres- sea urchin
2. Gray crescent- frog
3. Dorsal Lip of Blastopore- Amphibian, Frog*
4. Primitive Streak- chick, human

Micromeres- sea urchin

Primary Organizers

Note: clevage is equal at 2 cell stage

16 cell stage early clevage not complete

no green no orange but later these sections will become

Gray crescent- frog

Primary Organizers

Dorsal Lip of Blastopore- Amphibian, Frog*

Primary Organizers

Primitive Streak- chick, human

Primary Organizers

Primairy mesenchyme vs Secondary mesenchyme

Teleosts/Bony fish

Blastoderm/Blastocoele

Blastoderm does not surround the blastocoel, instead has cell death tube . Removed during excavation.

Ectoderm

Endoderm

Mesoderm

Ectoderm Blue/Green

Endoderm Yellow

Mesoderm Red/Orange

Ectoderm

Endoderm

Mesoderm

become...

Prospective Significance

Prospective Fate of a cell or group of cells due to their anatomical position in the embryo

Prospective Potency

Developmental Potential of a cell or group of cells under varying conditions, wherein new influences (inductive influences) are encountered.

Induction

When one cell or group of cells influences the fate of another cell or group of cells without necessarily affecting itself

Inductor

The cell or group of cells responsible for the influence mentioned above.

Embryonic Competency

The ability of cells to respond to the influence of an inductor

Period of competency is a fixed period of time.

Determination

Fixing the fate of cells during development(narrowing of the prospective potency so that it more closely equals the prospecting significance) when the prospective potency and prospective significance are the same we say that cells are fully determined (happens during the s-period of the cell cycle)

Differentiation

Physical (Anatomical) and Genetic/Biochemical (Physiological) expression of the fixed fate of cells.

Spacial Differentiation

Spatially different parts of the embryo take on different anatomical structure. Morphogenesis/ Organogenesis

Temporal Differentiation

Over a period of time different cells in an organ differentiates into different, specific cell types. Cytodifferentiation Histogenesis

Morphogenesis/ Organogenesis

Spacial Differentiation

Cytodifferentiation Histogenesis

Temporal Differentiation

Morphogenetic (Formative) Movements

Invagination- pushing in of an epithelium

Epiboly- Spreading of an epithelial layer so that it covers over epithelia

Ingression (immigration)- breaking-up of an epithelium followed by inward migration of individual cells

Involution- inward migration of an epithelium

Separation of epithelial layers

Local thickening followed by evacation

Invagination , Ingression, involution

Epiboly

Additional Morphogenetic Formative movements

• Separation of epithelial layers
• Local thickening followed by evacation

Draw Early Gastrulation

TOP

Red- Non-notochordal mesoderm

Orange- Chrdomesoderm

Yellow- Endoderm

Green- Neural Ectoderm

Blue- Epidermal Ectoderm

Draw Mid Gastrulation

BOTTOM

Red- Non-notochordal mesoderm

Orange- Chrdomesoderm

Yellow- Endoderm

Green- Neural Ectoderm

Blue- Epidermal Ectoderm

Villus Arrangement

Diffuse

Cotyledons

Zonary

Discoidal

Bidiscoidal

ICM=Inner Cell mass

TB- Trophoblast

HB- Hypoblast

EB- Epiblast

MES- mesoderm

YS- Yolk Sac

CH- Chorion

Chorion

Diffuse

Cotyledons

Zonary

Discoidal

Bidiscodal

Bidiscodial-same as discoidal but with 2 disks

Area Opeca Vasculosa

Area Pellucida

COLOR

mid gastrulation

When orange meets orange gastrulation stops.

blastula

early gastrula

late gastrula

Amnion

Allantois

Yolk Sac

Chorion

Yolk Stalk

Heart rudiment

Yolk plug

Gastrulation in the Chick

1. Invagination of primitive pit (streak)
2. Ingression of mesoderm

Primary Organ Rudiment Formation in the Chick

NO

SUCH

STUPID

LUCK

I

BROUGHT

APPLES

ANYWAY

1. Neural tube formation with epilepsy
2. Separation of the chordomersoderm from segimental mesoderm
3. Somites forom from dorsal portion of segmental mesoderm
4. Lateral plate mesoderm splits to form splanchnic mesoderm, somatic mesoderm, coelom
5. Intermediate mesoderm forms nephrostone
6. Body folds close forming gut
7. Exocoele forms amniotic folds
8. Amniotic folds form amnion and chorion (serosa)
9. Amniotic folds form yolk sacs

Primary Organ Rudiment Formation in the Chick

1. #formation with epilepsy
2. Separation of the # from # mesoderm
3. Somites forom from # portion of segmental mesoderm
4. ## mesoderm splits to form splanchnic mesoderm, somatic mesoderm, coelom
5. Intermediate mesoderm forms #
6. Body folds # forming gut
7. # forms amniotic folds
8. Amniotic folds form # and # (serosa)
9. Amniotic # form yolk sacs

Primary Organ Rudiment Formation in the Chick

1. Neural tube formation with epilepsy
2. Separation of the chordomersoderm from segimental mesoderm
3. Somites forom from dorsal portion of segmental mesoderm
4. Lateral plate mesoderm splits to form splanchnic mesoderm, somatic mesoderm, coelom
5. Intermediate mesoderm forms nephrostone
6. Body folds close forming gut
7. Exocoele forms amniotic folds
8. Amniotic folds form amnion and chorion (serosa)
9. Amniotic folds form yolk sacs

Hilde mangold

• Primary Organ Rudiment Formation in the Frog
• Discovery of Primary Embryonic Organizer by Hilde mangold
• demonstrated this effect with the frog’s dorsal lip (chordomesoderm)

Mangold ROL rude old lip

A.S.G. Curtiss crescent

demonstrated this effect with the frog’s gray crescent (presumptive chordomesoderm)

Determination

Determination vs Competency

?what a cell becomes vs its ability to become something ?

Types of Grafts

Always

Hang

Heavy

Xrays

1. Autoplastic Transplant (autograft)- donor and host same individual
2. Homolpastic transplant (homograft)- donor and host are different individuals of the same genus and species
3. Heteroplastic transplant (hetrograft)- donor and host of same genus but different species
4. Xenoplastic transplant (xenograft) donor and host more distant than genus

Autoplastic Transplant (autograft)

donor and host same individual

Homolpastic transplant (homograft)

donor and host are different individuals of the same genus and species

Heteroplastic transplant (hetrograft)

donor and host of same genus but different species

Xenoplastic transplant (xenograft)

donor and host more distant than genus