Basic Embryology

Question 1

The ___ is released from the ovary and caught by the ____ of the fallopian tube during ovulation

Answer 1

Secondary oocyte; fimbria

Question 2

The ___ of the fallopian tube is where fertilization usually occurs

Answer 2

Ampulla

Question 3

What will happen to an oocyte if it is not fertilized within 24 hours?

Answer 3

Degenerate and be reabsorbed in the oviduct

Question 4

Match the following parts of the sperm:

1) Tail with ____
2) Neck with ____
3) Head with ____

Answer 4

1) Flagellum
2) Mitochondria
3) Dense nucleus

Question 5

How does the sperm swim its way through the vagina?

Answer 5

Vagina -> Uterine Cavity -> Oviduct

Question 6

What does a sperm have to do to be capable of fertilizing the oocyte?

Answer 6

It has to undergo several changes as it passes through the uterine cavity and oviduct

Question 7

What is the sex chromosome constitution of a sperm? a secondary oocyte?

Answer 7

23 X or 23 Y; 23 X or 23 X

Question 8

This is the product of fertiization

Answer 8

Zygote

Question 9

This refers to the division of cells of a zygote into smaller embryonic cells after fertilization.

Answer 9

Cleavage

Question 10

In Zygotic cleavage, each increased embryonic cell is called ___.

Answer 10

Blastomere

Question 11

T/F: As the cleavage travels through the oviduct towards the uterus, the blastomeres get smaller and differentiate.

Answer 11

False: They get smaller, but increase in number

Question 12

When is a zygote called a morula?

Answer 12

When there are 12-32 blastomeres

Question 13

How is the blastocoel formed? What happens after it is formed?

Answer 13

Fluid from the uterine cavity enters the morula; Morula becomes the blastocyst

Question 14

The blastocyst separates into two parts: ___ and ___.

Answer 14

Trophoblast and Embryoblast

Question 15

Thin outer layer which will give rise to the placenta

Answer 15

Trophoblast

Question 16

Inner layer which will give rise to the embryo

Answer 16

Embryoblast

Question 17

T/F: Six days after fertilization, the embryonic pole of the blastocyst attaches to the uterine endometrium

Answer 17

True

Question 18

The trophoblast differentiates into two layers: ___ which makes the inner layer of ___ and ___ which makes the outer layer of ___ cells

Answer 18

Cytotrophoblast, mononucleated and Syncytiotrophoblast. multinucleated

Question 19

T/F: By the end of the second week, the blastocyst is successfully implanted into the uterine endometrium

Answer 19

False: first

Question 20

The development of ___occurs 6-10 days after fertilization

Answer 20

bilaminar embryo

Question 21

Differences between epiblast and hypoblast in terms of description

Answer 21

Epiblast: thicker layer composed of high columnar cells
Hypoblast: thinner layer composed of cuboidal cells

Question 22

This appears when a small cavity starts to appear within the epiblast and enlarges and in what phase?

Answer 22

Amniotic Cavity; Second

Question 23

The development of the primary yolk sac includes the cells from the ___ proliferating and migrating to the ___ -> A ___ forms and lines the cavity -> ___ becomes the primary yolk sac

Answer 23

Hypoblast, blastocoel, thin membrane, blastocoel

Question 24

The thin membrane lining of the primary yolk sac is called the

Answer 24

Exocoelomic membrane/Heussers membrane

Question 25

In the development of the chorionic cavity, cells from the primary yolk sac form the ___

Answer 25

Extraembryonic mesoderm

Question 26

The isolated spaces in the extraembryonic mesoderm will rapidly fuse to form a large isolated cavity called thhe

Answer 26

Chorionic cavity / Extraembryonic coelem

Question 27

Membrane surrounding the primary yolk sac is the

Answer 27

Exocoelemic Membrane or Heuser's

Question 28

Three layers of the chorionic membrane

Answer 28

1) inner layer: extraembryonic mesoderm 2) middle layer: cytotrophoblast 3) Outer layer: synctytiotrophoblast

Question 29

T/F: The secondary yolk sac is formed from the second wave of migrating epiblast cells

Answer 29

False: Hypoblast

Question 30

T/F: Once the chorionic cavity appears, the blastocyst's yolk sac is now the secondary yolk sac

Answer 30

True

Question 31

Two functions of the secondary yolk sac

Answer 31

1) Site of origin of primordial germ cells | 2) Selective transfer of nutrients to embryo

Question 32

T/F: Gastrulation happens in the third week

Answer 32

True

Question 33

During ___, the transformation of the bilaminar embryo into the trilaminar embryo occurs

Answer 33

Gastrulation

Question 34

The rapid growth of the embryo is characterized by the ___ and the ___.

Answer 34

Primitive streak and three germ layers

Question 35

The following occurrences happen in this stage: - Establishment of axial orientation - Following of notochord formation - Beginning of morphogenesis

Answer 35

Gastrulation

Question 36

The following are observed in the second week except: - Completion of implantation of blastocyst - Blastocyst formation - Formation of embryonic structures - Formation of extraembryonic stuctures

Answer 36

Blastocyst formation (First week)

Question 37

Canal formed in the primitive streak is called the ____. It is continuous with the small depression in the primitive node called the ___.

Answer 37

Primitive groove, Primitive Pit

Question 38

Formation of primitive streak: Proliferation and migration of cells at the ___ to the median plane of ___, from the ___ end to the ___ end.

Answer 38

Epiblast, Embryonic disk, Caudal, Cranial

Question 39

If there are remnants of the primitive streak, it can possibly lead to ___.

Answer 39

Sacrococcygeal teratoma

Question 40

T/F: The primitive streak marks the start of gastrulation and establishes orientation

Answer 40

True

Question 41

Sequentially arrange the steps of the development of the prechordal plate: 1) Cells stop migrating near the cranial end of embryonic disc 2) Cells proliferate to form the prechordal plate 3) Epidermal cells migrate cranially from the primitive node

Answer 41

3, 1, 2

Question 42

T/F: During the 3rd week of gastrulation, the intraembryonic mesoderm holds the ectoderm and endoderm together except at two regions: the oropharyngeal membrane and cloacal membrane

Answer 42

False - The intraembryonic mesoderm separates the ectoderm and the endoderm except at these two regions

Question 43

Oropharyngeal membrane becomes the ___ while the cloacal membrane becomes the ___.

Answer 43

Opening of oral cavity, opening of anus

Question 44

T/F: All three layers derived from the hypoblast

Answer 44

False - epiblast. Hypoblast gives rise to the primary yolk sac

Question 45

Match the following derivatives to their respective germ layer: ``` Notochord - ___ Thymus - ___ Nervous system - ___ Tooth enamel - ___ Dermis of skin - ___ Pancreas - ___ ```

Answer 45

``` Mesoderm Endoderm Ectoderm Ectoderm Mesoderm Endoderm ```

Question 46

The following derives from the endoderm except: ``` Epithelial lining of digestive tract Lining of urethra, urinary bladder, and reproductive system Thyroid Liver Cornea and lens of eye ```

Answer 46

Cornea and lens of eye (Ectoderm)

Question 47

The following derives from the mesoderm except: ``` Skeletal System Lining of body cavity Pancreas Adrenal cortex Muscular System ```

Answer 47

Pancreas (Endoderm)

Question 48

The following derives from the ectoderm except: ``` Nervous system Epithelial lining of mouth and anus Lining of body cavity Adrenal Medulla Epithelium of pineal and pituitary glands ```

Answer 48

Lining of body cavity (Mesoderm)