Embryology (early development) Flashcards Preview

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Flashcards in Embryology (early development) Deck (35)
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1
Q

what 4 main functions do cells show

A

proliferation
movement (chemotaxis) differentiation
loss (apoptosis)

2
Q

how do embryonic cells functon diffferently to omatic cells

A

mature cells normally show one characteristic at a time-

In an embryo, cells may show the proliferate, move and differentiate simultaneously
simultaneously.

3
Q

how does regulator factor expression produce different outcomes

A

Gradients/ combinations of regulatory factors;

Spatial/ temporal changes in these factors, or in the responses to them.

4
Q

Embryonic development is usually considered to start with….

A

fertilisation which leads

immediately into preimplantation development (PID) of the conceptus.

5
Q

wher and over what time period does PID occur

A

within the fallopian tube over a period of 6 days,

6
Q

what is PID characterised by

A

characterised by a series of cleavage

divisions that results in the formation of the morula (a ball of undifferentiated cells).

7
Q

what does the morula form

A

develops into a blastocyst-

8
Q

what are the key features of the blastocyt

A

has an outer layer of trophectoderm
an inner cell mass
and a fluid filled cavity.

9
Q

when does the blastocyt implant into the uterine lining and hwa happens when it does

A

(by 10 days post-fertilization)

inner cell mass
becomes a bilayer disk.

10
Q

what does the bilayer disk gve rise to

A

all of the tissues of the human fetus by

a series of complex changes…

11
Q

what is the bilayer dsk composed of

A

hypoblast and epiblast cells

12
Q

what are the complex changes which the bilayer disk undergoes

A

Gastrulation and Neurolation

13
Q

describe the process of gastrulation

A

convertes bilayer disk to trilaminar embryo, containing the three layers of germ cells.

(precursors to all tisues in the body)

14
Q

when does gastrultion occur

A

14-18 post-

fertilisation.

15
Q

does neurulation start after astrulation

A

NO

Neurulation is initiated before gastrulation is complete.

16
Q

describe the process of neurulation, what controls it

A

differentiation of
the ectoderm to generate the CNS,

under the control of the notochord in the
mesoderm

17
Q

how does the neural plate form a sealed tube

A

develops two folds which
increase in size until they meet over the neural groove and fuse to form the neural
tube.

18
Q

when does fusion of the 2 neual tubes occur

A

Fusion occurs during week 4 of development as the CNs becomes a sealed
tube.

19
Q

what is occuring in parallel with neurulation

A

precursors of other tissues are developing within the

embryo, and it is being converted from a flattened structure into a 3D embryo.

20
Q

during the third week of development whcih strcire outside the embryo are also developing

A

the primordial germ cells

cardiac/ vascular progenitors

21
Q

in which direcions does folding of the emryo occur

A

both laterally and in the anterio-posterior direction

22
Q

what can be said of the embrto by the end of week 4

A

precursors of all internal tissues have been laid down

many external structures are also developing.

23
Q

sumarise the events of week 3

A

Formation of trilaminar disc (mesoderm),
CNS & somites.
Blood vessel initiation. Initiation of placental villi. (3mm).

24
Q

summarise the events of week 4

A

Closure of neural tube. Heart, Face, arm initiated.

Umbilical cord. Elaboration of placental villi. (4mm)

25
Q

define conceptus

A

everything that is produced from the fertilised egg.

26
Q

define embryo

A

whole product of conception, includes cells that give rise to the baby
and everything else that results from conception such as the placenta and umbilical cord.

27
Q

when does embryonic development cease

A

after 8 weeks post-fertilisation as the conceptus

is nor clearly human and classified as a fetus.

28
Q

what are the 3 layers of the trilaminar embryo which gastrulation forms

A

ectoderm
mesoderm
endoderm

29
Q

what does the ectoderm give rise to

A

skin, nervous system

30
Q

what does the mesodem give rise to

A

skeleton, muscle, kidney, heart, blood

31
Q

what does the endoderm give rise to

A

gut, liver, lungs

32
Q

what does the grrove above the neural plate act as

A

negative regulator to

prevent proliferation occurring at the groove.

33
Q

In the second month what is happening

A

limbs, face and internal tissues (heart, lungs, gut) develop

looks human by day 56

34
Q

how does fusion of the neural folds occur

A

fusion point moves anteriorly and

posteriorly with neuropores at each end.

35
Q

how does brain develop

A

Fusion of tissues and elaborations results in brain

developments. The two halves of the brain form separately and then join.