embryology Flashcards
when is the pre-embryonic phase
0-3 weeks
when is the embryonic phase
4-8 weeks
when is the foetal phase
9-40 weeks
what haapens in week one of pre-embronic phase
zygote is forned, divides to blastocyst
Moves through uterine tube, to reach uterine cavity.
what does zygote form?
morula
what does morulas form
blastocyst
what happens in week 2 pre-embryonic phase
Implantation occurs in the uterine endometrial layer and placenta begins to develop (this may start by day 6 of 1st week)
Cells that later form the embryo form a bilaminar disc
Sacs, membranes and cord to nourish the human conceptus (baby) start to form
whats the uterine wall callled
endometrium
whats implantation
the blastocyst begins to burrow into the uterine wall
Cells that form the outer cell mass is initially called the
trophoblast
what does the trohpoblast form?
the chorion
whats the function of chorions
Implantation process (chorionic villi) Forms part of the placenta in due course Secretes human Chorionic gonadotropin (HCG) (used to detect pregnancy)
what hapens to the inner cell mass?
The cells of the inner cell mass form a 2–layered flat disc called the BILAMINAR DISC
what are the 2 cavities thta begin to form?
amniotic cavity and yolk sac
what are the main functions of placenta?
Foetal nutrition
Transport of waste and gases
Immune etc
Fertilisation zygote-> morula -> blastocyst with inner cell mass -> bilaminar disc with amniotic cavity above and yolk sac below
some key info init
Morula reaches uterine cavity -> blastocyst implants-> outer cells form chorionic villi which help implantation -> decidua basalis formed -> placental formation begins
where it all happens
what is GASTRULATION
Formation of germ layers
what is NEURULATION
Formation of neural tube
what happens in week 3
–GASTRULATION
NEURULATION
Development of somites
Early development of cardiovascular system
where does epiblast cells migrate into?
space between epiblast and hypoblast
what are the 3 germ layers?
Ectoderm
Mesoderm
Endoderm
Inner cell mass of blastocyst -> bilaminar disc -> primitive streak -> cells from primitive streak invaginate, displace hypoblast -> endoderm, mesoderm, ectoderm
yeet
when does heart beat start?
day 24
whats Teratology
Study of when things go wrong during development
what are Teratogens
environmental factors that cause abnormal development.
what is Congenital rubella syndrome caused by
contraction of german measles when pregnant
what are Malformed limbs due to
maternal use of Thalidomide
how many sperm penetrates the egg
one
what will a blastocyst reach if it moves through the uterine tube?
uterine cavity
which parent does mitochondria and cell organelles come from?
mother
If a father had an effected mitrochondria disease and the mother was uneffected, how will the children turn out?
What would happen if it was vise versa?
unaffected
the children would be affected
What is a morula
a solid ball of cells divded from a zygote
how does a morula become a blaszstocyst?
enlarges and divides further
what are the outer cells surrounding the blastocyst?
trohpoblast
what are the 2 types of population forming a blastocyst
trophoblast and inner cell mass
what is the genetic info of the trophoblast?
same chromosomal make up as the baby/ inner cell mass
what does the inner cell mass produce?
the baby
what is the inner lingin of the uterus
endometrium
whats the element in the fertilised ovum in the fallopian tube that makes it move
it has cilia
what happens if the cilia gets destroyed?
ectopic pregnancy (implantation in the tube, couldnt move out the tube)
what do chorions penetrate?
endometrium
what forms the placenta?
chorion
what is the decidua
endometrium
what hormone is secreted by the chorion?
hCG
what does the inner cell mass flatten to form?
epiblast and hypoblast
what sits above the epiblast?
amniotic cavity
what sits below the hypoblast?
yolk sac
what surrounds the embryo?
amniotic cavity
what is the main source of nutrition for embryo
umbilical cord
other than umbillical cord what else is a source of nutrition for an embryo?
yolk sac
how long does it take for the respiratory system to grow to full length with the lobes?
8 weeks
describe the steps for the growth of the respiratory system
Tubular outgrowth from foregut
This outgrowth will develop into trachea and lung buds
Trachea will separate from oesophagus and lung buds will proliferate.
Proliferating lung buds will invaginate laterally into the pleural cavities, so forming visceral & parietal pleura and the pleural cavity
Meanwhile, a transverse septal “shelf” will begin to develop between thorax and abdomen, below the pleural cavities.
. This shelf is composed of 4 components, which fuse to form the diaphragm
what does folding of the embryo give rise to?
primitive gut tube
what forms the foregut?
trachea and lungs
where does the gut tube form from?
endoderm
when is the development of the trachea and lungs?
4 weeks
where is the development of the trachea and lungs?
from ventral wall of foregut
where is the laryngotracheal groove
ventral part of the foregut
what does the diverticulum (endoderm) become invested with to form trachea and lung buds
mesoderm
where does the oesophagotracheal sputum develop?
between the oesophagus and trachea
what is a fistula?
an abnormal or surgically made passage between a tubular organ and the body surface, or between two hollow or tubular organs
what is atresia?
= a condition in which an orifice or passage in
the body is (usually abnormally) closed or absent.
what are common congenital abnormalities with the trachea and lung?
TOF (tracheoesophageal fistula) and astresia
what does the layers of visceral and parietal pleura form?
pleural cavity
what are the layers of visceral and parietal pleura formed from?
mesoderm
which layer does the lungs need as they develop
visceral pleurafrom the splanchnic mesoderm.
what does the thoracic wall become lined with? and where is this derived from?
parietal pleura, derived from somatic mesoderm.
whats the gap between parietal and visceral pleurae called? and what will this eventually become?
pleuroperitoneal canals
pleural cavaties
where does the pleuropericardial folds form around?
primitive heart and it seperates pleural cavities from pericardial cAVITIES
What develops into the visceral pleura?
the mesoderm which covers the outside of the lung
what becomes the parietal pleura?
the somatic mesoderm, covering the body wall from the inside
what are the stages of lung development
embryonic pseudo glandular canalicular saccular alveolar
what happens in the pseudoglandular stage?
Setup of all pulmonary structures except elements needed for gas exchange
what happens in the canalicular stage?
The terminal bronchioles give rise to tubes that make up respiratory part of the lung. Differentiation of epithelium into Type II pneumocytes which will synthesize the surfactant, and flat cells - Type I pneumocytes.
what happpens in the saccular stage
Formation of alveolar sacs. The alveolar sacs will be progressively divided into smaller subunits leading to the formation of alveoli.
what happens in the alveolar stage?
formation of the alveoli terminal sacs
what is surfactant composed of?
mixture of phospholipids and protiens
what is surfactant secreted by?
Type 2 pneumocytes
what does the septum transversum develop into
central tendon
what does Pleuroperitoneal membranes contribute to?
primitive diaphragm
what does Dorsal mesentery of oesophagus contribute to?
median portion & crura of diaphragm
what does Muscular ingrowth from lateral body walls contribute to?
peripheral parts of diaphragm
what are the four embryonic components that develops the diaphragm?
Septum transversum
Pleuroperitoneal membranes
Dorsal mesentery of oesophagus
Muscular ingrowth from lateral body walls
where is the septum tfansversum initially located in week three?
opposite c3-c5 somites
what are three major defects for congenital abnormalities
Failure of the diaphragm to completely close during development
Herniation of the abdominal contents into the chest
Pulmonary hypoplasia
whats a hernia
Herniais a general term used to describe a bulge or protrusion of an organ through the structure or muscle that usually contains it.
what are the three types of diaphragmatic herniae?
poaterolateral
anterior
central
what are the types of hiatal herniae
sliding hiatus hernia
paraesophageal hiatus hernia
