bio3: animal development

8/7/2019 BIO3: Animal Development

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Animal Development

bio3


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Pre-embryonic Development

ranges from GAMETOGENESIS to

FERTILIZATION

Oogenesis-differentiation of egg cellinto animal and vegetative hemispheres

animal pole (nucleus)

vegetal pole (yolk)


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During fertilization, the egg and sperm

nuclei fuse forming a zygote--

AMPHIMIXIS

Pre-embryonic Development


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Embryonic Development

Involves three main features:Cell division and growth

Morphogenesis

Differentiation

Has four stages: Cleavage

Gastrulation Organogenesis

Histological differentiation


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CLEAVAGE

The sea urchinEmbryo

MORULA BLASTULA


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The Toad Embryo

Toad eggs Mesolecithal (moderate

amount of yolk)

CLEAVAGE cell division without growth

- in toads, cleavage furrows

pass through the entire eggHOLOBLASTIC or total


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GASTRULATION certain cells begin to

push or invaginate

- the three germ layersare produced: ectoderm (outer layer),

endoderm (inner layer) and mesoderm

(produced by the migration of dorsal lip

of blastopore in between the ectodermand endoderm

The Toad Embryo


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Gastrulation

Embryonic germ layer Vertebrate adult structure

Ectoderm (outer layer) Epidermis of the skin, epithelial lining of mouth

and rectum, nervous system

Mesoderm (middle

layer)

Skeleton, muscular system, dermis of the skin,

circulatory, excretory, reproductive systems,most epithelial linings, outer layers of

respiratory and digestive systems

Endoderm (inner layer) Epithelial lining of digestive and respiratory

tracts, associated glands of these enzymes,

epithelial lining of urinary bladder


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Organogenesis-- NEURULATION

establishment of the nervous system

The Toad Embryo


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The Toad Embryo


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The Chick Embryo

Chick eggs POLYLECITHAL (large

amount of yolk)

CLEAVAGE restricted to a small area,cytoplasmic disk; furrow do not cut

across the entire cytoplasm

MEROBLASTIC


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Chick embryo development

http://crazy-desktop-wallpaper.blogspot.com/2007/05/stages-of-chick-embryo-development.html


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GASTRULATION

The Chick Embryo


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GASTRULATION primitive streak stage

The Chick Embryo

13-16hrs


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Head fold stage (21hrs)


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Early somite stage (36-40hrs)


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Flexion-torsionstage (60 hrs) Limb bud stage(96 hrs)


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The Chick Embryo

Organogenesis head fold stage (21 hrs),

early somite stage (36-40 hrs), and

flexion-torsion stage (60hrs)


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Extra-Embryonic Membranes

CHORION lies next to the shell; carries

on gas exchange

AMNION membrane around the fetus;with protective amniotic fluid which

bathes the embryo

ALLANTOIS collects nitrogenous wastes

YOLK SAC surrounds the remaining

yolk, which provides nourishment


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Extra-Embryonic Membranes


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The HumanEmbryo


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Cleavage occurs over several days following

fertilization. The zygote divides as it travels through

the oviduct. By the time the cilia of the oviduct

deliver the embryo to the uterus, the embryo is a ball

of cells called a blastocyst. The blastocyst implants

in the endometrium.


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A blastocyst forms nearly a

week after fertilization

Four membranes

protect and nourish the

embryo, which consists

of three tissue layers.


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Nutrients and waste products are exchanged between the fetus and the

mother within the placenta. The umbilical vein (red) carries oxygen-rich

blood and nutrients to the fetus. The umbilical arteries are blue,

indicating that they carry oxygen-depleted blood and waste products

away from the fetus.


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Placental circulation: materials are exchanged by

diffusion, active transport, and selective absorption.

Not by direct blood contact.

Structure and function of the placenta video


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During labor, hormones stimulate the uterus to contract. The

contractions push the baby out of the mother's body.


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The Process of Birth


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Post-Embryonic Development

Metamorphosis transformation of the

immature stage or larva to adult stage

Insects exhibit 2 types ofmetamorphosis:

Hemimetabolous (incomplete)metamorphosis- cockroach

Holometabolous (complete)metamorphosis- butterfly


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Hemimetabolous

metamorphosis


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Holometabolous metamorphosis



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bio3: animal development

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