embryology Flashcards

1
Q

What becomes of the mesoderm?

A

Divides into Paraxial mesoderm–>intermediate mesoderm–>lateral plate (splachnic and somatic) and separately the notochord

Forms:

Somite- Muscle , vertebrae and ribs, dermis

Intermediate mesoderm- kidneys and gonads

Lateral plate- somatic [parietal serosa, dermis of ventral organs, CT of limbs], splanchnic [viseral serosa, gi and respiratory wall]

notochord- nucleus of pulposus of intervertebral discs

lateral plate- somatic (connective tissue, dermis of ventral body region, parietal serosa) and splanchnic mesoderm (wall of digective tract, respiratory tract except the epithelial tract, heart, BV, viseral serous)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

during which week does the body take shape?

A

week 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the epiblast give rise to ?

A

Amnion outer membrane and amniotic sac cavity by the inner membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name the developmental features at 12 weeks

A

Liver and head are still dominant

Blood cell formation begins in bone marrow, liver and spleen

Sex of fetus can be determined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what the major embryological events?

A

organs form from the three primary germ tissues and emergence of the basic body plan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Pair the following to its respective layer:

A. dermis of the ventral body region

B. pigment cells

C. visceral serosa

D. Hair

E. dermis of the dorsal body region

F. Joints

G. sclerotoma

A

A. Somatic mesoderm (lateral mesoderm)

B. Ectoderm

C. Splanchnic mesoderm (lateral mesoderm)

D. Ectoderm

E. Somite

F. Somatic mesoderm (lateral mesoderm)

G. Somite (vertebrae and ribs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name the prenatal periods and time frame

A

Embryonic period – first 8 weeks
Fetal period – remaining 30 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How and when does implantation occur?

A

After the blastocyst has been released, the trophoblast differentiate and invade the wall the of the endometrium around day 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is the neural tube made?

A

By neurulation.

Via induction (ability of cells to influence developmental direction of other cells) of the mesoderm cells, the midial sagital portion dorsal to the primitive streak thickens on the ectoderm to form the neural plate. As it folds inward, a neural groove is formed. The neural folds approach each other, fuse and pinch off to form the neural tube. The cranial portion becomes the brain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the somatic mesoderm and splanchnic mesoderm? Where do they come from? What do they become?

A

The are formed by the division of the lateral plate.

paraxial mesoderm–>intermedite mesoderm–>lateral plate–> divides into the somatic and splanchnic mesoderm and form the coelom (serous body cavities)

Somatic mesoderm- parietal mesoderm of the coelom that meshes with the ectoderm

Splanchnic mesoderm- viseral mesoderm of the coelom that meshes with the endoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where do the early blood cells and blood vessels come from?

A

tissues around the yolk sac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When is the fetus propotional? what else happens during this period?

A

At month 4

sucking motions of lips occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which of the following are paired correctly:

A. Gonads arise from the intermediate mesoderm

B. Muscles, ribs and bones arise from the somite

C. dermis of the ventral body region arise from the somatic mesoderm

D. epithelial lining of digestive and respiratory tracts arise from the splanchnic mesoderm

E. epithelial lining of digestive and respiratory tracts arise from the endoderm

F. Sclerotoma, dermatoma and Myotoma arise from you somite

A

A, C, E,F

B. bones arise from somatic mesoderm of the lateral plate (bones are connective tissues)

D. Wall of the digestive and respiratory tracts arise from the splanchnic mesoderm not their epithelial lining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the endoderm form?

A

Inner epithelial lining of the gut tube
Respiratory tubes, digestive organs, and urinary bladder
and Notochord – gives rise to nucleus pulposus within intervertebral discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When is the fetus most susceptible to teratogens?

A

morphological abnormalities from week 3-7 and mostly physiological defects from week 8 and on

highest mortality during weeks 1-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What becomes of the ectoderm?

A

This top layer undergoes neurulation starts to form the:

CNS - brain and spinal cord and epidermis(hair, nails and glands of skin)

neural crest becomes the PNS, BV of the head and neck, pigment cells and portions of the skeleton.

13
Q

What is considered normal and premature birth?

A

normal at 37 weeks and premature before that

15
Q

where are each germ layers and how are they formed?

A

Endoderm: formed from migrating cells that replace the hypoblast layer

Mesoderm: formed btw the epiblast and endoderm

ectoderm- formed from the epiblast cells that remain on the dorsal surface

15
Q

The last 4 weeks of the embryonic development is important because….

A

limb buds form and all major organs are in place,

at week 8 the embyro finally looks like a human

**the Head is disproportionately large **

17
Q

where does conception occur?

A

in the lateral third of the unterine tube

18
Q

Define somites and explain what gives rise to them?

A

Somites are our first body segments like muscles and dermis that come from the paraxial mesoderm.

19
Q

What are the distinct features of a fetus at week 8?

A

Large head and liver.

Bone formation has begun

Limbs are complete and fingers and toes are no longer webbed

cardiovascular system is fully functional

21
Q

what is a blastocyst and how is it formed?

A

Blastocyst (fluid filled structure) made during day 5. What has been formed is an outer cell mass (the trophoblast), consisting of many flat cells and the morula forms a inner cell mass at the embryonic pole making that space for the blastocyst cavity

day 6- it frees itself from the pellucid zone aka the “first birth”

22
Q

How is the PNS formed?

A

From the neurulation of the ectoderm but specifically from the neural crest made after the neural tube is made on the caudal portion of the neural plate.

  • it forms the sensory nerve cells (ANS)
23
Q

What is the primitive node and what does it give rise to?

A

Primitive node- a swelling at one end of the primitive streak on the epiblast dorsal/caudal portion that gives rise to the notochord.

24
Q

what is the notochord? how is it made? What does it eventually become?

A

Notochord determines the longitudinal axis that eventually becomes nucelus pulposus within the intervertebral discs

It is formed by the primitive node on the primitive streak and the endoderm through induction on the MESODERM

PENDing

Primitive Node

ENDoderm

NotochorD

25
Q

What is embryology ?

A

Embryology – study of the origin and development of single individual

27
Q

Describe the formation of the three-layered embryo

A

During week 3, the epiblast forms a primitive sreak (raised groove on the dorsal surface- tail or caudal portion) that undergoes gastrulation (process of invagination) to form the three primary germ layers: endoderm, mesoderm, and ectoderm.

28
Q

WHen does the zygote become a blastocyst? explain the process

A

during week 1

  1. oocyte become a zygote during fertilization in the lateral portion of the uterine tube
  2. Zygote –> blastomeres (zygote 4 daughter cell)
  3. 4 cell–> Morula @ day 3 (solid cluster of 12-16 blastomeres)
  4. Morula –> early Blastocyst (fluid filled structure)–> late blastocyst has a trophoblast outer layer and the morula forms a inner cell mass at the embryonic pole
29
Q

what are the major fetal events?

A

organs grow in size and complexity

30
Q

What type of deficiency can cause neural tube defects and how?

A

Maternal folic acid (vitamin B9) is needed for productin of cells and RNA/DNA synthesis.

A lack of can prevents closure and pinching of the neural tube.

32
Q

what does the hypoblast become?

A

extends ventrally to form the yolk sac which eventually become the primitive gut (digestive tubes)

**** the yolk sac is NOT a major source of nutrients for the embryo****

33
Q

Where do the following arise from?

A. visceral serous

B. blood vessels

C. Kidneys

D. Glands of the skin

E. blood vessels in head and neck

A

A. splanchnic mesoderm (lateral plate mesoderm) of the Mesoderm layer

B. splanchnic mesoderm (lateral plate mesoderm) of the Mesoderm layer

C. Intermediate mesoderm of the mesoderm

D. Ectoderm

E. Ectoderm

34
Q

What is the bilaminar embryonic disc? How is formed?

A

The layers of epiblast and hypoblast made from the inner cell mass

35
Q

What are the epidermis and dermis made from?

A

epidermis- ectoderm (top layer, also makes the CNS)

dermis- mesoderm (

36
Q

when do the testes reach the scrotum in males? What else is happening in this period?

A

Month 7

eyes open, fingernail and toenials are complete

bone marrow is the only site of blood cell formation