Survey of Embryonic Development

Question 1

Name the structures

Answer 1

1. Fertilization (zygote)
2. Blastomeres 2 cells (cleavage)
3. Bastomeres 4 cells (cleavage)
4. Blastomeres 8 cells (cleavage)
5. Morula (blastomeres 32 cells) “solid ball”
6. Blastula (hollow ball)
7. Blastocyst/ gastrula
8. Implanted blastocyst

Question 2

What is happening in 1?

Answer 2

Fertilization: sperm and ovum

Time zero

Question 3

What is the term for 2 and what is its time duration?

Answer 3

Embryo

Weeks 3-9

Question 4

What is the term for 3? How long does this stage last?

Answer 4

Fetus.

From 9 weeks to birth

Question 5

What is happening in 4? What is the time?

Answer 5

Implantation into uterine wall

Week 1

Question 6

Label

Answer 6

1. Oocyte
2. Zygote (fertilized egg)
3. 4 cell stage
4. Morula
5. Blastocyst
6. Implanting blastocyst

Question 7

Label

Answer 7

1. Endometrium
2. Uterine endometrial epithelium
3. Inner cell mass
4. Trophoblast (outside cells)
5. Blastocyst cavity
6. Lumen of uterus

Question 8

Label

Answer 8

1. Endometrial stoma with blood vessels and glands
2. Syncytiotrophoblast (“legs”)
3. Cytotrophoblast
4. Inner cell mass (future embryo)
5. Trophoblast (outside of blastocyste)
6. Lumen of uterus

Question 9

Label

Answer 9

1. Inner cell mass = embryoblast
2. Trophoblast = outside cells
3. Blastocyst cavity
4. Blastocyst

Question 10

Label

Answer 10

1. Amnion
2. Allantois
3. Chorion
4. Yolk sac
5. Yolk (nutrient)
6. Albumen
7. Shell
8. Amniotic cavity with amniotic fluid
9. Embryo

Question 11

Label

Answer 11

1. Decidau basalis (bottom of mom’s uterus- where belly button forms)
2. Maternal blood
3. Chorionic villus
4. Umbilical blood vessels in umbilical cord
5. Amnion
6. Amniotic cavity
7. Yolk sac
8. Chorion
9. Decidua capsularis (cover of embryo)

Question 12

What is the purpose of the amnion?

Answer 12

Encases and protects embryo against mechanical and temperature, trauma

Question 13

What is the purpose of the yolk sac?

Answer 13

•Yolk sac: transfers nutrients to embryo. Replaced by placenta in humans.

Question 14

What is the purpose of the allantois?

Answer 14

•Allantois: repository of embryo wastes. Replaced by placenta in humans.

Question 15

What are the three germal layers?

Answer 15

1. •Ectoderm: nervous tissues, epidermis and melanocytes.
2. •Mesoderm: bones, muscles, mesenchyme, reproductive system, urinary system.
3. •Endoderm: digestive system, respiratory system, endocrine system.

Question 16

What does the ectoderm contribute to?

Answer 16

•Ectoderm: nervous tissues, epidermis and melanocytes.

Question 17

What does the mesoderm contribute to?

Answer 17

•Mesoderm: bones, muscles, mesenchyme, reproductive system, urinary system.

Question 18

What does the endoderm contribute to?

Answer 18

Endoderm: digestive system, respiratory system, endocrine system

Question 19

What are the three basic activites that ensure the formation of a viable offspring?

Answer 19

1. Increase in cell number and growth
2. Cellular specialization
3. Morphogenesis

Question 20

Describe the process and timing of implantation in the human

Answer 20

The zygote becomes a bastocyte that travels down the uterine tube to the uterine lining to implant. The blastocyte will have the three layers (ecto-, meso-, and endoderm)

Takes about a week

Question 21

Define the decidua basalis and its function

Answer 21

Decidua Basalis

• Maternal part of the placenta.
• Located in contact with the chorion frondosum where the fetus attached to the uterine wall.

Question 22

General function of the human placenta

Answer 22

Metabolism, Transportation, Endocrine Secretion

Question 23

Define the decidua capsularis and its function

Answer 23

Decidua Capsularis

• Originates from the maternal endometrium which “plugged” the area where the blastocyst invaginated on the uterine wall.
• In contact with the chorionic laeve which is on the abembryonic pole of the chorionic cavity.
• Gets stretch when the fetus starts to grow and extends into uterine cavity

Question 24

What is the function of the chorion villi of the placenta?

Answer 24

Function of chorionic villi

Holds the placenta in place via the cytotrophoblastic shell, connecting the fetal part to the maternal part

“fingers of the chorion”

Question 25

What two structures make up the umbilical cord?

Answer 25

1. Yolk sac 2. Allantois

Question 26

What is morphogenesis?

Answer 26

The formation of functioning organ systems

Question 27

What is a zygote?

Answer 27

A fertilized egg

Question 28

What is meant by fertilization?

Answer 28

Fertilization is the process of when the egg's and sperm's nucleu fuse to form a single nuclues, after the egg is penetrated by the sperm cell.

Question 29

What is a blastomere?

Answer 29

Blastomeres are the successively forming and dividing cells of the zygote forming a mass.

Question 30

What is the series of mitotic divisions, without intervening growth periods after fertilization called?

Answer 30

Cleavage

Question 31

What is the result of cleavage?

Answer 31

Cleavage results in a multicellular embryonic body

Question 32

What is the morula and at what stage does this occur?

Answer 32

The morula is a solid mass of cells during the 32-cell stage, which resembles a raspberry.

Question 33

What is the blastula

Answer 33

Blastula is the hollowing out of the morulla from a solid ball to a ball of cells surrounding a central cavity. \*The blastula is the final product of the cleavage

Question 34

Identify the early gastrula form, which follows the bastula in the developmental sequence.

Answer 34

#6 Moves from a solid ball to a hollow ball

Question 35

What is the result of gastrulation?

Answer 35

The result of gastrulation is turning the single layer bastula into a three layered embryo form. Each layer corresponds to a primary germ layer from which the body tissues develop.

Question 36

What is the final product of cleavage?

Answer 36

#7 & 8 Blastocyst

Question 37

Label the blastocyst

Answer 37

1. Trophoblast 2. Blastocyst cavity 3. Inner mass 4. Hypoblast 5. Epiblast

Question 38

Label the implanted blastocyst

Answer 38

6. Blastocyst cavity 7. Endoderm 8. Ectoderm 9. Lacuna 10. Cyto-tropho-blast 11. Syn-cytio-tropho-blast 12. Amnion 13. Amniotic cavity

Question 39

Label

Answer 39

1. Uterus 2. Placenta 3. Amniotic cavity 4. Urinary bladder 5. Cervical canal 6. Vaginal canal

Question 40

Label the placenta

Answer 40

1. Amnion covering of placenta 2. Umbilical vein (1 big tube) 3. Umbilical arteries (2 little tubes)

Question 41

Label 1-6

Answer 41

1. Umbilical vein 2. Umbilical arteries 3. Chorion 4. Decidua basalis 5. Myometrium 6. Maternal endometrial arteriole (spiral arteriole)

Question 42

Label 7-13

Answer 42

7. Maternal endometrial venule 8. Uterine artery 9. Chorionic villi 10. Intervillous space 11. Fetal blood vessels 12. Amnion 13. Wharton's jelly

Question 43

What is the name of this tissue?

Answer 43

Ovary mature follicle

Question 44

What is the name of this tissue and its structure?

Answer 44

Ovary Corpus lutem

Question 45

Label

Answer 45

1. Urinary bladder 2. Spermatic cord 3. Testicular blood vessels 4. Epididymis 5. Tunica albuginea covering the testis 6. Tunica vaginalis 7. Scrotum 8. Shaft of penis 9. Glans penis 10. Cresmaster muscle 11. Ureter 12. Ejaculatory duct opening 13. Spermatic cord 14. Ischiocavernosus muscle 15. Prostate 16. Seminal vesicles 17. Ampulla of vas deferens

Question 46

Label

Answer 46

1. Head 2. Lens placode 3. Pharyngeal arch 4. Upper limb 5. Lower limb 6. Amniotic cavity 7. Amnion 8. Umbilical blood vessels 9. Yolk sac 10. Chorionic villi

Question 47

Label

Answer 47

1. Mature (pre-ovulatory) follicle 2. Corpus lutem