Embryology Flashcards

1
Q

Define the stages of embryology

A

zygote is formed and divides to form a blastocyst. moves through uterine tube to reach uterine cavity. implantation occurs in the uterine endometrial layer and placenta begins to develop

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2
Q

Describe the formation of the gametes and fertilisation

A
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3
Q

Describe the formation of the blastocyst and its implantation into the uterine wall

A

During fertilization, the sperm and egg unite in one of the fallopian tubes to form a zygote. Then the zygote travels down the fallopian tube, where it becomes a morula. Once it reaches the uterus, the morula becomes a blastocyst. The blastocyst then burrows into the uterine lining — a process called implantation.

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4
Q

Outline the formation of the placenta, placental villi and the general functions of the
placenta

A

villi for vascularisation of the placenta.- give foetal brain nutrition

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5
Q

Describe the formation of the bilaminar disc

A

cells of inner mass flatten and form a 2 layered bilaminar disc and two cavities begin to form called amniotic cavity and yolk sac

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6
Q

Describe the formation of the trilaminar disc

A
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7
Q

function of blastocyst cavity

A

to get nutrients to the cell

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8
Q

what are the outer layer of the cells called

A

trophoblasts

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9
Q

what happens to the cells that form the outer cell mass known as trophoblast

A

divide to form 2 layers and forms a chorion which develops finger like processes called chorionic villi

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10
Q

function of chorion

A

involved in inplantation, forms part of the placenta in due course and secretes human chorionic gonadotropin

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11
Q

main functions of placenta

A

foetal nutrition, transport of waste and gases, immunity

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12
Q

gastrulation

A

formation of germ layers

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13
Q

neurulation

A

formation of neural tube

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14
Q

what is the primitive streak

A

formed in the midline of the epiblast by the dipping in of cells (invagination). Once primitive streak forms the axis of the embryo is formed

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15
Q

describe gastrulation

A

epiblasts cells migrate to lie in-between epiblast and hypoblast layers. cells displace hypoblast layers and forms 3 germ layers
1. ectoderm
2. mesoderm
3. endoderm
trilaminar disc is now formed

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16
Q

describe neurulation

A

ectoderm cells sink down to form a solid tube called a notochord. Notochord induces ectodermal cells in the midline to form a neural tube

17
Q

describe mesoderm

A

neural tube causes mesoderm to thicken and spilt into 3 parts called
paraxial mesoderm, intermediate plate mesoderm and lateral plate mesoderm and lateral plate splits again

18
Q

what does paraxial mesoderm form

A

somites and divides into 3- dermatome, myotome and sclerotome

19
Q

what does each mesoderm form

A

paraxial forms somites
intermediate plate mesoderm forms kidneys and reproductive
lateral plate mesoderm forms body cavities and coverings

20
Q

Briefly describe folding of the embryo and the formation of the gut tube.

A

during folding the somatic (parietal) mesoderm folds down to surround the splanchnic (visceral) mesoderm if the intraembryonic body cavity. The yolk sac becomes absorbed into the primitive gut

21
Q

describe the origin of the lung buds

A

trachea and lungs bud out from the ventral/anterior wall of the primitive foregut. closely surrounded by lateral plate splanchnic mesoderm. a septum develops between oesophagus and trachea to separate them and lung buds will enlarge to from the lungs

22
Q

Describe the development of the bronchial tree

A

tracheal epithelium and glands are derived from endoderm
tracheal smooth muscle, connective tissue, and cartilage are derived from visceral (or splanchnic) mesoderm. At week 4 trachea splits into two bronchi

23
Q

Describe the development of the diaphragm

A

Septum transverse forms the central tendon

Somatic mesodermal folds from in from the peripheral wall to fuse with sputum transverse. They close off pleuroperitoneal canals and stop abdominal contents getting into thorax

skeletal muscle grows inwards from the peripheral body wall forming muscular part of diaphragm

Dorsal mesentery of the oesophagus attaches to the posterior thoracic wall and skeletal muscle covers the dorsal mesentery to from the diaphragmatic crura

24
Q

how does the gut tube form

A

folding of the somatic and sphanchinic mesoderm from the endoderm

25
Q

development of pleura

A

splanchnic layer of lateral plate mesoderm forms visceral pleura
somatic layer of lateral plate mesoderm forms parental pleura.

26
Q

what is fistula

A

an abnormal passed between 2 epithelialized tubes or surfaces

27
Q

what is atresia

A

a condition in which a passage in the body is closed or absent

28
Q

what is the pericardioperitoneal canal

A

space between the splanchnic and somatic mesoderm around the lungs that is initially continuous with the pericardial and peritoneal cavity. the cavity needs to be sealed off to maintain pleural cavity pressure

28
Q

what is the pericardioperitoneal canal

A

space between the splanchnic and somatic mesoderm around the lungs that is initially continuous with the pericardial and peritoneal cavity. the cavity needs to be sealed off to maintain pleural cavity pressure

29
Q

how do you seal the pericardoperitoneal canal

A

formation of pleuroperocaridal folds formed from the body wall and lined by somatic mesoderm. once this occurs it becomes known as the pleural cavity

30
Q

formation of alveolar crest

A

by the secondary crests that protrude from the walls of the terminal sacs

31
Q

where does trachea form from

A

foregut endoderm

32
Q

splanchnic mesoderm develops into what structure

A

visceral pleura

33
Q

when does gas exchange start to occur

A

saccular stage

34
Q

parietal pleura develops from what

A

somatic mesoderm