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Development Chapter 21, 46, 47 Development Chapter 21, 46, 47

Development Chapter 21, 46, 47 - PowerPoint Presentation

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Development Chapter 21, 46, 47 - PPT Presentation

Mostly Human Development See pages 636 and 640 for overview of Phylogenetic tree Early Development Early Development Developmental Tissue Layers Sponges0 Gridera Centophores2 All other Phyla3 ID: 755804

cell cells endometrium egg cells cell egg endometrium differentiation week folding form embryo sperm stage cleavage development corpus estrogen follicle fsh morula

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Slide1

Development

Chapter 21, 46, 47

Mostly Human Development

See pages 636 and 640

for

overview

of Phylogenetic treeSlide2

Early Development

Early Development: Developmental Tissue Layers, Sponges-0,

Gridera

/Centophores-2, All other Phyla-3

Hormones released in hypothalamus

FSH: Follicle Stimulating Hormone

LH: Luteinizing Hormone

At menstruation, there are multiple concurrent events

Estrogen and Progesterone (hormones from the ovaries) gone down its concentration

FSH increases in concentration

Menstruation is occurring. The endometrial lining of the uterus is flushed out.

When Estrogen levels drop, the brain monitors and produces FSH. The target of the increased at FSH is in the ovaries.

A cluster of cells in the back of the ovary. Each contains the germ line cell. Primary

oocye

that started meiosis before birth. But this was arrested in prophase.

After 2 or 3 days, usually only one Oocyte continues to matureSlide3

The maturing of

Oocyte

1. The

surrounding cells form the

Graffarian

Follicle.

2. Continues

into the first division of

meiosis

3. the

developing follicle moves down the Ovary and growing in cell

number

4. the

follicle continues to mature for about 14 days – it enlarges spatially and more

cells

the

meiotic dividing primary oocyte is in a cavity with some surrounding nursing

cells.

The

nursing cells are adding nutrients and other components to this meteoric cell to prepare for it to become an

egg

fully

developed follicle (

egg/ovary)

outer

follicle cells synthesis and release Estrogen (steroid) Maturing outer follicle becomes a hormone producer..

5. Increased

Estrogen stimulates the rebuilding of the Endometrium of the

uteral

wall and the decline of FSH

concentration.

6. The

brain monitors increased estrogen and as a feedback mechanism, it decreases the release of FSH

.Slide4

The maturing of Oocyte

7. The

developing follicle also can secrete inhibits, this is also a hormonal message to the hypothalamus and anterior pituitary to decrease the release of FSH.

An egg is being formed – both still requires 2

nd

meiotic division

the Estrogens and

Inhibins

decrease with equals FSH increases

Endometrium is rebuilding. The endometrium is continuing to form under hormonal direction and or stimulates currently estrogens. Mostly made of mucus, blood, glycogen. It's being formed in case of the pregnancy. If there is a pregnancy endometrium is the nutrient, food, 02 etc. source and will maintain the first part of the pregnancy.

This is for internal fertilization only not for things like fish as the ovarian follicle nears maturity, it's:

estrogenic output decreases

This is a signal to the brain or hypothalamus to cause anterior pituitary

release more FSH

release a very large amount of luteinizing hormone.

The estrogen decrease is not enough of drop to stop the endometrium from building

spike of LH stimulates to events to occur and a concurrent third eventSlide5

Ovulation

Ovulation: Oocyte sent to the

filopian

tubes and

ovaduct

with nursing cells (triggers 2

nd

meiotic division)

Remaining follicle cells collapse in and forms the Corpus

Luteum

.

Two possible concurrent events during ovulation

the released egg travels down the

ovaduct

by Cilia on

ovaduct

cells and contraction of smooth muscle cells, called

peristolsis

.

The Corpus

Luteum

becomes the new Hormone Factories:

prodcues

Estrogen and Progesterone. - causes LH and FSH to decrease, causes Endometrium to enlarge more

(possibility) the egg can be fertilized, but the egg is viable (able to function) for about 24 hours

to become fertilized

sperm must be present during

fallopion

tubes during 24 hours

sperms must contact, attach and release nucleus into

eggSlide6

Ovulation

Situation #1: if no sperm is present:

corpus

luteum

will function longer if pregnancy has occurred. There will be no message with no sperm. 10-11 days if not pregnant, corpus

luteum

deteriorates.

If both estrogen decreases and

inhibins

decreases, then FSH increases and LH increases. If estrogen decreases and progesterone decreases, more FSH increases then LH.

Situation #2: Sperms (high number of sperms and obstacles to sperms) meets, attaches and fertilizes egg

sperm must overcome obstacles (get lost, environment shock, go up wrong side, get through the nursing cells, Nona

Puluza

)

Multiple sperm must work to fertilize sperm, but if multiple sperm enter the egg (

polysperm

), then the egg is worthless and discarded.

Only one sperm fertilize, protection to avoid

polysperm

. - but its dependent on species.Slide7

Sea Urchins (

polysperm

)

Sea Urchins (

polysperm

)

Sperm releases acrosomes. Acrosomes are hydrolytic digestive enzymes. That digests the

zona

peluza

up to the

vitealie

layer. Actin fibers of sperm attaches to receptors on the egg membrane and pulls it in. Receptors are very specific

the membrane of both cells fuse. Consequences:

sodium pathways open up and let sodium in. The egg becomes positively charged. No more sperm can attach.

Cortical vesicles are all around inside the egg. Calcium

rugles

out of the cell and cortical vesicles release and pushes the membrane and

vitealine

layer apart. Water does the job.

Vitealine

stiffens and becomes the fertilization. Envelope plasma membrane returns to normal charge.

Slow box 3

polysperm

takes about .5 – 1 min. but is long lasting the egg plasma membrane returns to its condition. The texture of the

vitalin

layer of egg changes. The plasma membrane re-polarizes

.Slide8

Sea Urchins (

polysperm

)

The cytoplasmic increases in concentration calcium also initiates the metabolic and functional changes with the egg cell.

Increases cellular respiration

and increases ATP in cell

increases in protein synthesis

DAG, intracellular messenger molecule activates its output of the cell, so the cytosol becomes more basic. When these two events is occurring the sperm's nuclear starts to swell and in about 20 min. after entering the egg, the two nuclei fuse together. Now a to end

nuclear's

, fertilization, and the zygote.

Male and female genetic info come

togetherSlide9

Zygote

Mammals

extra coating around the populated egg. It is a surrounding corona of the formal nursing cell. They surrounded the egg in the follicle and continue to surround the related egg.

Zona

Pellucida

extracellular matrix woven with glycoproteins that cross-link into a 3-D network.

One of these three glycoproteins, ZP3 (

zona

pellucida

glycoprotein #3) also functions as the sperm's receptor

binding of plasma membranes cause

depolorazation

of cell membrane (fast block)

corticle

vesicles,

corticle

reaction, changes the

zona

pellucida

and rigid (slow block)

zona

pellucida

does not separate from egg

events change inside the ovum, 2

nd

meiotic divisions occurs in mammalsSlide10

Zygote

the egg doesn't go through second meiotic division unless sperm

perpetrates,

it forms a second polar body due to uneven

cytokenesis

.

The female nucleus and male do not fuse

both

separately

replicate DNA, still

separate

as mitosis occurs

both nuclei lose the nuclear envelope

all chromosomes line up in metaphase in one plane, then fertilization. The cell finishes mitosis including

cytokenesis

.

This is now:

2 cell zygote, each has a 2n nucleus

the initiation of cleavage

the genetic identity of the offspring is established,, unique

sex chromosomes determine sexual

determination

the

next events are in the mammalian zygote traveling through the

ovaducts

4 days to reach the uterus.

Meanwhile, corpus

luteum

is fully formed, this produces estrogen and progesterone; endometrium is growing, cleavage happens while traveling in

ovaduct

.Slide11

Cleavage

number of cells increases, mitosis with

cytokenisis

cells grow in number, not in size.

Cells are genetically identical to each other.

Egg must contain many organelles to fuel all these cells may grow.

the cytosol and all non-nuclear organelles of the egg just one cell have now become the cytosol and non-nuclear organelles in many different descendent cells. The organelles especially the mitochondria of the developing offspring came only from the egg. Mitochondrial inheritance is from the mother.

2 types of cleavage

Spiral cleavage

by 8 cells stage, the cells do not align. The upper for cells are shifted upward from the lower 4 cells.

A pattern in

protesostome

, mouth opens first in the digestive tract, very early cell differentiationSlide12

Cleavage

Spiral

cleavage (cont.)

Organisms

with spiral cleavage tend to have early differentiation only certain cellular identities in the future and possible as development progresses.

cellular differentiation for

multiorganism

SL's progress through this differentiation of development, the types of cells they can end up being in the final organism fully developed becomes more and more limited.

During this process, various potential genetic info is being turned on and off. Many that are turned off, stay off and all descendent cells. Consequently, there are many types of expressions that may make the descendent cells can never perform.

Organisms with spiral cleavage have early cell

differitiation

Radio Cleavage

by the eight cell stage, upper four cells aligned with lower four cells

Deuterostomes

. No differentiation yet (cell division starts later)

all cells are still aligned

anus opens first, mouth secondSlide13

Morula

we have radio cleavage. At this point the developing offspring is traveling through

ovaduct

. Cleavage is

occurring.

While still in the over duct, one of the cells no longer has any of its surface in contact with the outer

zona

pellucida

. No cell

differentiation

yet. It is in intercell, cells in contact with

zona

pellucida

or outer surface are outer cells.

Once this occurs, both inner and outer cells have developmental stage is now called a

morula

. Still a solid ball of cells. The zygote has become a

morula

.

In organisms like us:

still no cell differentiation. The cells

aretotspotent

:

intercell can be exchanged with any outer cell and still have all cellular potentials ahead of it.

The

zona

pellucida

remains intact through

themorula

stage. It is still in the cleavage

stage

it

is the

morula

that enters the uterus. 4-5 days since ovulation. Likewise, it would be in on fertilized egg entering the uterus at the same time. The

morula

cells are still

totipotent.

Totipotent:all

cells possible, not differentiated, any inner cells can be exchanged with any outer cellSlide14

Morula

Upon

morula

entering the uterus, several events occur relatively simultaneously:

the

zona

pellucida

starts to disappear. Consequently the volumes can now expand without much restrictions

the

zona

pellucida

stops a tube pregnancy

a forms in this developing offspring. It is no longer a solid ball of cells. The cavity is the

blastocystic

cavity.

This is a new stage in development

the outer cells form a single layer around the blastula. The cells have become

trophoblasts

(protect and support tissues). They were in contact with the

zona

pellucida

the inner cells are pushed to one cluster within the cavity at a whole. The inner cells have become a single

embryoblasts

(forms the embryo)

those two cells are not exchangeable because it is the first differentiated cells

The location of a cell highly affects its differentiation. Environment for a cell is important

.Slide15

Morula

The

trophoblasts

that are in contact with the embryo blasts within a succession of events, do the following:

release a sticky substance

form

microvili

on the plasma membrane outside the blastula.

Both help with attachment of the endometrium. The two entities try to assure attachment of blastula to the endometrium has a embryo blast facing the endometrium.

The endometrium also form microvilli in its later stages

These

trophoblast

in contact with the embryo blasts, once attachment has occurred, it will release a hormone called human

chonionic

Gondotrophin

.(

hCG

). The target for

hCG

ourselves of the Corpus Lutein in the mothers ovary. Without this hormonal message between mom and partially developed offspring the corpus lutein will degenerate within 10 to 11 days. With the

hCG

, the corpus lutein last several months. Without it menstruation follows

.Slide16

Morula

However, in corpus

luteum

receiving

hCG

, the corpus lutein stays for several more months. Estrogen and progesterone levels stays high concentration. Consequently:

the endometrium continues to enlarge instead of

demostrating

.

No new cycle starts. No further start of eggs in the follicles. No at SH is released.

This is the starter pregnancy. Due to

hCG

the corpus

luteum

now lasts about 10 to 8 weeks past ovulation.

HCG is the development and offspring's message to the mother not to flush out the developing offspring. It is the support for material, food, nutrients, 02, etc. for the first part of the pregnancy. This is about 6 to 7 days after ovulation for the attachment. There is no menstruation.Slide17

Second week (7-14 days

since

ovulation)

implantation; shifting of

Embryoplast

into two cell layers; growth of

trophoblasts

.

Implantation

the blastula is completely covered with endometrium material

trophoblasts

release enzymes that digest into the endometrium

carves a place for the blastula

opens cavities that increase blood flow (pools of internal blood), lacunae

to start implantation,

trophoblasts

next to the endometrium search release enzymes that digest into the endometrium

endometrium grows around the blastula – continues all week

trophoblasts

not touching

embryoblasts

, starts to touch endometrium

more enzyme release

fibrin coagulum: “scabs” over the blastula – completing implantation, blastula is completely coveredSlide18

Second week (7-14 days

since ovulation)

meanwhile, the

trophoblasts

grow and divide into the endometrium (cellular differentiation, will later become the placenta) / the support develops faster than the offspring, take nutrients from mother

meanwhile, the

embryoblasts

change location, go through one major differentiation

embryoblasts

in contact with

trophoblasts

become

Epiblasts

Epiblasts

move away from the

trophoblasts

embryoblast

not in contact with

trophoblasts

become hypoblasts

amniotic cavity formsSlide19

Third Week

formation of Primitive Steak (depression by cells folding in)

cellular differentiation of

Epiblasts

into Ectoderm and Endoderm and then Mesoderm.

Hypoblasts reproduce and make one cell layer and makes a yolk sac.

The

Blastocistic

Cavity has membranes dividing it

The

epiblasts

on the

aminotic

side differentiate into ectoderm but they are limited by the walls of the blastula.

The cells that push into the hypoblasts turn into

endoerm

.

Endoerm

begins to divide themselves – lines the yolk sac, one layer think.

Once Endoderm lines the egg sac and ectoderm on the amniotic side, a cavity forms between the cell. Mesoderm fills the cavity

Folded in cells form Endoderm then Mesoderm

Primitive streak is formed (depression by cells folding in): the crease in the Ectoderm cell

Trilaminar

disk formed or three developmental layersSlide20

Third Week

the process is now called Gastrulation (Gastrula)

zygote –

morula

– blastula – gastrula

Invagination

the folding in of cells from an outer surface to an interior. Environment = invagination

Mesoderm begins migrating toward the

ephalic

end (head); it does not migrate in

procordial

plate

Migrating Mesoderm

it travels from primitive node toward the

Prochordial

plate. These cells turn into (differentiate) cells of the

Notocord

. The Notochord is the first characteristic that appears for

chordata

.

It travels beyond the

procordial

plate develops into Cardiogenic tissue, forms the muscles and values of the heart

.Slide21

Third Week

The notochord tissue is the first developed tissue that is still present in an adult. All other cells (mesoderm, ectoderm,

etc

) do not stay.

Toward the end of the 3

rd

week, the mesoderm next to the notochord differentiates into somite cells.

Somites

are structures made of

somitic

cells. They form in pairs on either side of the notochord. The first pair is between the primordial node and the

pricordial

plate.

Somites

continues to form about 3 pairs a day

til

the end of the 5

th

week. Each pair alternates on the cephalic end to the caudal end.

The Gastrula continues to grow and the primitive streak gets shorter. The streak totally disappears by the 4

th

week.

Once the

somites

appear, the Embryo stage begins.

Gastrulization

(folding) continues into the Embryo stage.

Zygote –

morula

blatula

– gastrula – embryoSlide22

Fourth Week

42-44 somite pairs have names

starting from the cephalic end

4 Occipital pairs – skull

8 cervical pairs

12 thoracic pairs – rib cage

5 lumbar pairs – lower back

5 sacral pairs – lower back

8-10 coccygeal

paris

– only 3 remain after development; tail for 4-5

th

week of development (Apoptosis)

as

somites

grow, the Neural Crests grow closer and closer, they eventually connect.

The trapped Ectoderm turn into neurons and Glial cells

The neural tube becomes the spinal chord, hollow dorsal nerve tube

organogensis

, starting of organ forming

the widest part of the

nureral

take at the cephalic end becomes the brain

Notochord = axis of symmetry, bilateral symmetrical

organizational locate for somite formation

the location of a cell determines what the cell differentiates into.

Cells around the notochord receive

horomones

that cause cell

differentiationSlide23

Somite dispersal 4-5th

week

Somite cells differentiate into other cells; they “fall apart”

the

somites

near the notochord proliferate an disperse.

The migrating cells differentiate into

osteoblasts – bone forming cells

chondroblasts

– cartilage forming cells

fibroblasts – connective tissue

one

somitic

pair = one vertebra, encases neural tube and notochord

the other remaining somite cells migrate and differentiate slightly later

differentiate –

myotome

(forms skeletal muscle) – follows osteoblasts,

chondroblats

dermatome – dermis, subcutaneous (form under/inner layer of skin)

Neural crest cells disperse and differentiate into front face, nose, teeth, dermis of skin, upper jaw.

In abdominal region,

adrenal medulla and some neurons, lots of differentiation (gene regulation

)Slide24

Somite dispersal 4-5

th

week

Meanwhile, growth an folding (ectoderm, mesoderm); endoderm so far has been a barrier from yolk sac but not much else, get trapped and passively move around and become internal

the upper cells (mesoderm) have been pushing the endoderm cells

2 major folding types

longitudinal – head and tail forming (cephalic, caudal)

½ of yolk sac is inside the fold

heart has swung down, cardiogenic cells migrate to below the head

amniotic cavity eventually surrounds the embryo dragged by

growing

Mesoderm cells

transverse/lateral folding – side folding

side to side folding – contemporary to longitude folding and somatic dispersal

in the

thoray

bones wrap around to form rib cage (

ostcoblasts

,

chordroblasts

)

longitudinal folding is complete before lateral folding is complete. Heart must be captured.

Some endometrium is captured in a interior environment. This differentiates into digestive tracts, also lungs, pancreas, liver.

The amniotic cavity is enlarged as surrounds the embryo. Cellular differentiation occurs mostly in embryonic cells. Few types of cells become many cells. (organogenesis)Slide25

During fourth week

the heart forms from

cardiogenetic

material

begins to contract even before there is blood.

Cardiac muscles differentiate from gene

cardiogenetic

material

fish – 2 chambers, mammals – 4 chambers

chambers form in the thorax cavity

invaginations (folding)

form various tissue on the outside that are captured on the inside (

otic

pit, lens

placode

, hair follicle)

intestines form outside of embryo and are folding into our gut via yolk sac folding

the yolk sac and connecting stalk twist, umbilical chord.Slide26

During fourth week

Aptoptosis

planned cell death

plays port in development and life

Gradients in the development of Embryos; blood cell and blood vessel formation – 4 areas

formation of blood system all over the embryo

inside the embryo, outside the yolk sac, connecting stalk, in the stem villi that will become the placenta

mesoderm –

angioblats

– form blood vessels –

pluribotential

– any type of blood cell

blood cells connect into the placenta via

ambilical

chord and this allows nutrients to be passed from mother to child. Blood never touchesSlide27

Eight weeks

Eight weeks after ovulation the Embryo stage is over, and the fetal stage begins.

Zygote –

morula

blatula

– gastrula – embryo – fetus

the placenta begins to fully functions

exchanges with circulatory system (nutrients, food, gases, water)

Elimination of waste

maintains the rest of pregnancy by releasing hormones (

estogen

and progesterone)

Corpus

Luteum

dies and

regeneartion

hCG

when the placenta begins to function.

Many outward characteristics are

noticable

½ of mass and size is in the head

eyes aren't rotated

foreward

all organs have started to form (organogenesis)

most of cellular differentiation has already formed, not allSlide28

Eight weeks

Placenta

develops before the embryo

by the 10

th

week, the placenta is fully functioning

umbilical cord is transferring nutrients

the fetus is entirely encased in the amniotic cavity

the placenta is as big as the developing offspring mass-wise

lots of folding in placenta – more surface area – more exchange

the circulatory system must not be exchanged – fatal

membranes keep the systems separate

the membranes are semi-permeable

Electrolytes

neural and muscle function needs these

calcification of bones

osmotic pressure

cellular integrity (co-factors)

enzymatic

co-enzymesSlide29

The Fetal Stage

A time of major growth (some cell differentiation)

embryo stage – cellular differentiation and organogenesis

sex differentiation occurs at this time (9

th

-10

th

week), (Early fetal stage)

the

Genetulia

will develop male characteristics if testosterone is present (TDF present) ,XY

if no testosterone female characteristics will form XX (TDF absent)

the product of TDF is a regulatory protein that turns on the genes for making testosterone among others

ovaries or testes come from the same

tissueSlide30

What Can Go Wrong?

Genetic Incompatibility – mother and father don't fit

Chromosomal Abnormalities – trisomy

some can make. Most do not it to birth

most problems happen in the first two weeks after fertilization. 42 % of

evolutated

eggs and sperms present do not survive in the 2 weeks.

Teratogens

begins to have impact after the first 2 weeks

any outside agent that influences malformations or debilitating problems

have a major impact in the embryonic stage (major cellular differentiation)

Rubella (German Measles) Virus, Alcohol (heart problems, growth deficiencies, mental/learning disorders, joint problemsSlide31

What Can Go Wrong?

Hormones

effective at low concentrations

masculinity hormones (testosterone)

estrogen and progesterone imbalance causes termination

endocrine disruptor

carcinoma of vagina.

Alkaloids (

Nicotin

) – cigarettes, antibiotics (tetracycline, streptomycin)

anticoagulants (causes fetus to hormone) not

Heprin

– doesn't cross the placenta

pathogens (Rubella,

Cytomegavirus,HIV

)

Radiation (X-rays,

radioacitivy

), and cause cancer

chemicals –

murcury

, LSD, tranquilizers, agent Orange

not all effects are immediate, some present themselves over time.