TBL 5B General Embryology

Question 1

Fertilisation usually occurs at the _____ of the uterine tube.

Answer 1

ampulla (Widest part of the fallopian tube)

Question 2

The lateral end of the Fallopian tube has finger-like projections known as _____. These projections help to bring the oocyte into the fallopian tube.

Answer 2

fimbria

Question 3

If the oocyte is not fertilised in the ampulla, it will pass along the fallopian tube into the _______, where it degenerates.

Answer 3

uterine cavity

Question 4

The plasma membrane of the oocyte is surrounded by a glycoprotein coat known as ___________.

Answer 4

zona pellucida

Question 5

The glycoprotein coat surrounding the plasma membrane of the oocyte, known as zona pellucia, is in turn surrounded by layers of follicular cells known as ________.

Answer 5

corona radiata

Question 6

Fertilisation occurs in 3 phases. Rearrange the following.

A) Penetrate zona pellucida

B) Penetrate corona radiata

C) Fusion of plasma membranes of oocyte and sperm.

Answer 6

1. Penetrate corona radiata
2. Penetrate zona pellucida
3. Fusion of plasma membranes

Question 7

The head of the sperm is covered with ______, which releases hydrolytic enzymes to dissolve the zona pellucida around the egg.

Answer 7

acrosome

Question 8

During fusion of plasma membranes of the egg and sperm, the ______ and ______ of the sperm remains behind.

Answer 8

plasma membrane and mitochondria

Question 9

When the first sperm touches the oocyte, the plasma membrane of the oocyte depolarises. ___________ will release enzymes to cause the zona pellucida to become impenetrable to other sperms. These prevent _______.

Answer 9

Cortical granules will release enzymes; preventing polyspermy

Question 10

Compaction occurs after the __-cell stage, where the blastomeres change their shape to tightly align themselves against each other by tight junctions to form a compact ball of cells.

Answer 10

8-cell

Question 11

The 16-cell stage embryo is known as ______.

Answer 11

morula (mulberry)

Question 12

Shortly after the morula (___-cell stage) enters the uterine cavity, the fluid from the uterine cavity passes through the zona pellucida to form the __________ in the morula.

Answer 12

blastocyst cavity

Question 13

At the 16-cell stage, the blastomeres are separated into 2 parts - inner cell mass (known as _________) and outer cell mass known as __________.

Answer 13

ICM - embryoblasts

outer cell mass - trophoblast

Question 14

5 days after fertilisation, the blastocyst hatches out of the ________, and is ready for implantation.

Answer 14

zona pellucida

Question 15

Implantation refers to the blastocyst attaching itself to the ___________.

Answer 15

endometrium epithelium

Question 16

Once implantation to the endometrium occurs, the trophoblast differentiates into 2 layers - ______ and _______.

Answer 16

synctiotrophoblast (outermost layer) and cytotrophoblast (inner layer)

Question 17

The ________ of the blastocyst has finger-like projections which penetrate the endometrium of the uterus to implant the blastocyst.

Answer 17

synctiotrophoblast

Question 18

________ pregnancy refers to blastocyst implant in abnormal locations outside the uterus.

Answer 18

Ectopic pregnancy

Question 19

In the 2nd week of development, the embryoblast differentiates into 2 layers - _____ and _____. This is known as the formation of bilaminar germ disc from the embryoblast.

Answer 19

Epiblast (3rd) and hypoblast (4th)

Question 20

A cavity known as the ______ then forms between the epiblast and the trophoblast.

Answer 20

amniotic cavity (lined by amnioblast cells)

Question 21

Around 9 days after fertilisation, the formation of vacuoles in the _______ takes place. These vacuoles fuse to form larger _______.

Answer 21

formation of vacuoles takes place in the syncytiotrophoblat; they fuse to form larger lacunae

Question 22

During the lacunar stage, the formation of ______ membrane also occurs. This membrane is formed by the hypoblasts cells, migrating along the internal aspect of the cytotrophoblast. The blastocyst cavity is now known as the ________/primitive yolk sac.

Answer 22

exocoelomic membrane

blastocyst cavity is now known as exocoelomic cavity/yolk sac.

Question 23

At day 12 stage, there is further growth of the __________ erodes the maternal endometrial capillaries. That would result in early uteroplacental circulation. The blood flows into the _____ of the embryo.

Answer 23

growth of syncytiotrophoblast; blood flows into the lacuna

Question 24

After early uteroplacental circulation, there is a formation of _______ outside the embryo, which is developed between the cytotrophoblast and the exocoelomic membrane.

The cavity develops within the mesoderm is known as ___________.

Answer 24

extraembryonic mesoderm

cavity - extraembryonic coelom

Question 25

The extraembryonic mesoderm is divided into two parts - __________mesoderm and __________ mesoderm.

Answer 25

splanchnopleuric mesoderm (covering the yolk sac); somatopleuric mesoderm (Covering the cytotrophoblast)

Question 26

The extraembryonic mesoderm forms a ________, which is connecting the embryo to the trophoblast. This is going to develop into the umbilical cord.

Answer 26

connecting stalk

Question 27

At the end of week 2, the lower half of the primitive yolk sac is pinched off the form the ________ yolk sac.

Answer 27

secondary yolk sac

Question 28

The first sign of gastrulation is the formation of the _________.

Answer 28

primitive streak

Question 29

The primitive streak is formed by the cells of the ______ moving towards the midline, where they accumulate and form the primitive streak.

Answer 29

epiblast

Question 30

__________ is the process of forming the three germ layers.

Answer 30

Gastrulation

Question 31

(Gastrulation) Some of the epiblast cells displace the hypoblast cells, forming the _______.

Answer 31

endoderm

Question 32

(Gastrulation) Other epiblast cells lie between the epiblast and the newly created endoderm, to form _______.

Answer 32

mesoderm

Question 33

(Gastrulation) The cells that are remaining in the epiblast form the ______.

Answer 33

ectoderm

Question 34

The ________ is formed by the mesodermal cells from the primitive pit, which migrates cranially, and form a median cellular cord. This structure defines the primitive mid line axis of the embryo.

Answer 34

notochord

Question 35

The bilaminar prochordal plate is the future (anal/oral) office. It represents the cranial end of the embryo.

Answer 35

oral

Question 36

The bilaminar cloacal membrane is the future (anal/oral) office. It represents the caudal end of the embryo.

Answer 36

anal

Question 37

The notochord induces the formation of the __________, which gives rise to the brain and spinal cord.

Answer 37

neural plate

Question 38

Which embryonic tissue gives rise to the neural plate? A. Ectoderm B. Mesoderm C. Endoderm D. Notochord

Answer 38

Answer: A) Ectoderm (neuroectoderm)

Question 39

__________ cells are derived from the neuroectoderm. These cells give rise to Schwann cells, sensory and autonomic ganglion, adrenal medulla and melanocytes.

Answer 39

Neural crest

Question 40

The notochord is formed from (mesoderm/endoderm/ectoderm) tissue.

Answer 40

mesoderm

Question 41

________ ectoderm gives rise to epidermis, hair, nails, cutaneous and mammary glands, anterior pituitary gland, enamel of teeth, inner ear and lens.

Answer 41

Surface ectoderm

Question 42

Mesoderm will further differentiate to form three layers. | What are these three layers?

Answer 42

1. Paraxial mesoderm 2. Intermediate mesoderm 3. Lateral plate mesoderm (which is divided into intraembryonic somatic mesoderm and intraembryonic viscera mesoderm)

Question 43

The ________ mesoderm gives rise to the kidneys and gonads.

Answer 43

intermediate mesoderm

Question 44

The paraxial mesoderm are organised into segments known as _________.

Answer 44

somites

Question 45

The _______ mesoderm gives rise to the skeleton (except skull), connective tissue, skeletal muscles and dermis of the skin.

Answer 45

paraxial

Question 46

The ___________ mesoderm gives rise to connective tissue of viscera and limbs, serous membranes of pleura, pericardium and peritoneum, blood and lymph cells, _________ and lymphatic systems.

Answer 46

Lateral plate mesoderm; cardiovascular system

Question 47

The endoderm gives rise to the _________ of gastrointestinal tract, liver, pancreas, urinary bladder and respiratory tract.

Answer 47

epithelial lining

Question 48

_________ period refers to the 3rd to 8th week of development post fertilisation. This refers to the period of organogenesis.

Answer 48

Embryonic

Question 49

The __ to __ week of embryo development is the most sensitive to outside factors, such as environmental hazards, pharmaceutical agents and drugs of abuse. (teratogens)

Answer 49

3rd to 8th week (embryonic period of organogenesis.)