Human Development - Fertlilization to Birth

Where does Human development begin?

in the oviduct with fertilization

what is fertilization?

Joining of a male and female gamete to form a Zygote

What is a Zygote?

Single cell with a full set of chromosomes (46)

What does the Zygote undergo whilst travelling down the oviduct to the uterus?

Cleavage

What is cleavage?

cell division without cell growth / enlargemnt

After the Zygote undergoes cleavage what happens next?

the zygote continues to divide and forms a Morula

What is a Morula?

a zygote composed of identical cells

Once the Morula reaches the uterus it is known as?

A Blastocyst

What is a Blastocyst?

hollow ball of cells, composed of two layers

What are the two layers of a blastocyst?

Inner cell mass

Trophoblast

What is the trophoblast?

Outer layer of the Blastocyst

• develops into a membrane that will nourish and protect the developing embryo

What is the process called when the blastocyst imbeds into the endometrium?

Implantation

Once implantation occurs what happens?

The individual is now Pregnant

Release of a hormone called Human Chorionic Gonadotropin (hCG) occurs

What is Human Chorionic Gonadotropin (hCG)?

Hormone secreted by the trophoblast during implantation

What does hCG maintain?

maintains the corpus luteum past the time it would degenerate

hCG signals the Corpus Luteum to produce?

progesterone and estrogen, maintaining the endometrium and prevents menstruation

Following implantation, cells begin to?

differentiate as they undergo gastrulation

What is Gastrulation?

formation of the three primary germ players

what are germ layers?

the first layer of cells formed during embryo development

How many layers do germ layers consist of, and what are they?

Three Layers

• Ectoderm

• Mesoderm

• Endoderm

What is the ectoderm?

Outer Germ Layer

• skins and nervous system

What is the mesoderm?

Middle Germ Layer

• organ systems and muscle

What is the endoderm?

Inner Germ Layer

• Lungs and digestive tract

What is a Gastrula?

embryo with three primary Germ Layers

When an embryo has three primary germ layers what is it called?

Gastrula

Gastrulation marks the beginning of?

Morphogenesis

what is Morphogenesis?

A time in which structures start to form through differentiation

what is deferentiation?

specialization of cell function

What do the cells of the mesoderm do during morphogenesis?

form a notochord (future skeleton)

What do the cells of the ectoderm do during morphogenesis?

fuse into a neural tube (future spinal cord and brain)

Once the embryo has a formed neural tube what is it called?

Neurula