Embryology (Part 1) Flashcards Preview

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Flashcards in Embryology (Part 1) Deck (171)
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1

During embryonic development, what event occurs on day six?

Implantation in the uterine wall

2

What is the gene that is expressed at the base of limbs in a zone of polarizing activity?

Sonic hedgehog (SHH) gene

3

The sonic hedgehog gene regulates patterning along the _____ (anterior-posterior or cranial-caudal) axis.

anterior-posterior

4

Name 2 genes expressed at the apical ectodermal ridge (the thickened ectoderm at the distal end of each developing limb).

Wnt-7 and FGF

5

What is the gene responsible for proper organization along the dorsal-ventral axis?

Wnt-7

6

What gene is responsible for the lengthening of limbs?

FGF

7

Which embryonic layer responds to products of the FGF gene?

The mesoderm

8

How does the FGF gene cause limbs to lengthen?

It stimulates mitosis of the underlying mesoderm

9

What phenotype would be seen if there was a mutation in the homeobox gene?

There would be defects in segmental organization

10

Day 0 of fetal life is marked by the _____ of an ovum by a sperm.

Fertilization

11

What is formed when a sperm fertilizes an ovum?

The zygote

12

At what stage of fetal development does implantation occur?

The blastocyst stage

13

The embryo exists as a _____ disk during the second week of development.

Bilaminar

14

What two layers make up the bilaminar disk?

The epiblast and the hypoblast

15

During fetal development, the process of _____ occurs during the third week, which gives rise to a trilaminar disk.

Gastrulation

16

If an embryo has a notochord and the neural plate is beginning to form, how many weeks old is the embryo?

3 weeks old

17

If an embryo has a primitive streak, how many weeks old is the embryo?

3 weeks old

18

During what part of embryonic development does organogenesis occur?

Weeks 3-8

19

In an embryo, the neural tube forms from a neural plate between which days?

Days 18-21

20

The embryo is most susceptible to teratogens during what time period?

Weeks 3-8

21

During what week of development does the heart of an embryo begin to beat?

Week 4

22

During what week of embryonic development do the upper and lower limb buds begin to form?

Week 4

23

When is the first time the fetus begins to move and looks like a baby?

Week 8

24

During what week of development do embryos first have genitalia with either male or female characteristics?

Week 10

25

During embryonic development, what stage begins on day 2?

The zygote stage (2 haploid cells form a single diploid cell)

26

During embryonic development, what stage begins on day 3?

The morula stage (morula is latin for mulberry and occurs after the 16-cell stage)

27

During embryonic development, what stage begins on day 5?

The blastocyst stage (containing an outer layer of cells and an inner cell mass)

28

During embryonic development, what event occurs on day 6?

Implantation

29

What embryonic structure implants itself into the uterine wall on day 6?

The blastocyst

30

After the primitive streak, name three structures formed by neural precursor tissue.

Neural plate, neural crest, and neural tube