Chapter 17. Development and Aging

Fertilization. [Figure 17.1]

Extraembryonic membranes – Origins in reptiles.

Chorion.

Amnion.

The amniotic fluid.

Yolk sac.

Allantois.

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The extraembryonic membranes in human be-ings. [Figure 17.2]

The placenta:

Early embryonic development:Zygote6 Cleavage (1 cleavage 30 hours)6 Morula (3 days)6 Embryo6 Implantationst

(day 7)6 Fetus (beginning of 9th week)

Morphogenesis.

Differentiation.

Early development. [Figure 17.3]

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The formationof the embryo.[Figure 17.4]

The origin of tissues and theembryonic germ layers. [Figure17.5]

Ectoderm

Endoderm

Mesoderm

Fetal circulation. [Figure 17.7]

Internal development of the male and female reproductive systems. [Figure 17. 9]

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Abnormal development of genitals.Example: Testosterone insensitivity syndrome.

The birth process. [Figure 17. 11]

Theories of aging:It may be genetic.

It may be a whole-body process.

Extrinsic factors play a part.

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