Chapter: ? Development

Question 1

What is the difference between male and female gametes?

Answer 1

The size and amount produced

Question 2

What is the prenatal period?

Answer 2

Time between conception and birth

o Formation of a zygote, up to birth

Question 3

What is the embryonic period?

Answer 3

Conception to the first 8 weeks

Question 4

What is the fetal period?

Answer 4

8 weeks to birth

Question 5

What is the uterus?

Answer 5

where organisms will develop

Question 6

What are the ovaries?

Answer 6

where female gametes are produced and then released

Question 7

What is the Oviduct (Fallopian tube)?

Answer 7

• Lateral third of the fallopian tube: where the sperm “attack”
• Where the female gamete finally finishes meiosis

Question 8

What are the fimbria?

Answer 8

cilia that “catch” the eggs between ovary and fallopian tube

Question 9

What is a zygote?

Answer 9

a diploid cell produced by the interaction between male and female gametes
o Sperm brings 23 chromosomes. Egg brings 23 chromosomes

Question 10

What happens by the fifth day?

Answer 10

o As you divide, the zygote makes its way down the fallopian tube
 By the 5th day, the zygote has split into 4 cells

Question 11

What is a morula?

Answer 11

A collection of 12-16 cells

Question 12

What is a blastocyst?

Answer 12

Blastocyst was differentiated from the morula

o (inner cell mass, blastocyst cavity, trophoblast)
o Reaches uterus around day 4
o Implantation of blastocyst on day 7
 Into the uterine wall (endometrium)

Question 13

What happens to the inner wall around the 7/8th day?

Answer 13

Differentiates into the epiblast and the hypoblast

Question 14

What is the epiblast layer?

Answer 14

o Organism and the amniotic sac (water cushion that surrounds the uterus)
 Single layer of cells
 Primitive streak, tail, and node
•(Gastrulation)

Question 15

What is the hypoblast layer?

Answer 15

Yolk sac

Question 16

What does the tropoblast become after 7 or 8 days?

Answer 16

Placenta

Question 17

What happens during gastuaration?

Answer 17

o Formation of the three primary germ layers
    Ectoderm: become skin
    Mesoderm: become heart, bones
    Endotherm: become lungs, gut
o Formation of Primitive streak

Question 18

What happens around day 14-15?

Answer 18

Migration of cells from the Epiblast on the dorsal surface through the primitive streak displace underlying hypoglast cells (will become the endotherm)

Question 19

What happens during day 16?

Answer 19

Mesoderm later forms through movement of the epiblast cells through primitive streak

Question 20

What happens to left over cells after the mesoderm forms from the primitive streak?

Answer 20

Left over cells become ectoderm

Question 21

Describe the formation of the notochord

Answer 21

o Is a stiffening rod (located under ectoderm) that is later modified into cartilage in the vertebrate
 Runs towards the head of the embryotic disc
o Sends signals the ectoderm
 Cells under the notochord differentiate into the neural plate to make our nervous system
 Forms the nervous system/ nervous tissue
o Neural folds have closed forming the neural tube
 Neuralation: neural tube is invaginated down to the mesoderm, forming the neural groove
 Folic acid prevents problems with neural tube
• Top portion will become cortex, other part will become spinal cord

Question 22

What happens to the ectoderm during day 24?

Answer 22

• Ectoderm will fold to form a cylindrical shape, like folding paper into a tube (Day 24)
o Can start to see the adult body plan

Question 23

When can the human body plan be seen?

Answer 23

day 28

Question 24

What is the function of the yolk sac?

Answer 24

To provide nutrients until week 4

Question 25

How is the growing embryo sustained?

Answer 25

-In placental mammals the mesodermal tissues interact with trophoblast tissues to form the choriono

-Amniotic sac surrounds the fetus
 Filled with amnion fluid

Question 26

What is the function of the placenta?

Answer 26

 The placenta forms the chorion and uterine wall
• Exchanges nutrients, gases, wastes, and antibodies (from mother to fetus)
• Contains arteries and veins that goes to the placenta to the umbilical cord
o Fetal blood (deoxygenated)flow goes into chorionic vilius
 Fetal capillaries allow gas and nutrient exchange

Question 27

What is gestation?

Answer 27

Also known as pregnancy, in humans is 266 days and is divided into trimesters

Question 28

What happens during the first trimester?

Answer 28

o In the first trimester the embryo becomes a fetus
-Characterized by rapid cell division and tissue differentiation
• Fetus is more susceptible to damage
-Heart begins to beat by week four
-Limbs form by week eight

Question 29

What happens during the second trimester?

Answer 29

• The limbs elongate and fingers, toes, and facial features form
• First fetal movements are felt by the mother

Question 30

What happens during the third trimester?

Answer 30

• Internal organs mature
• The brain goes through sleep-wake cycles
• Birth occurs when the lungs are mature