Intro 30: Derivatives of endoderm and pharyngeal arches Flashcards
ENDODERM gives rise to…
EPITHELIAL lining of various body parts
WEEK 3, during GASTRULATION
and EARLY SOMITE DEVELOPMENT, what do we get of the FOREGUT, MIDGUT, HINDGUT
patterning of the ENDODERM into FOREGUT, MIDGUT, HINDGUT PROGENITOR DOMAINS
- future sits of foregut, midgut, hindgut are determined
as a result of EMBRYO FOLDING in WEEK 4..
FOREGUT and HINDGUT POCKETS FORM
- as the ENDODERMAL CUP is transformed into a GUT TUBE
what happens to the MIDGUT as foregut and hindgut pockets form during week 4?
MIDGUT remains in contact with the YOLK SAC until it DEGENERATES much LATER
ENDODERMAL SPROUTING results in the formation of what in the FOREGUT
UPPER SECTION of foregut:
primordial
- THYROID
- THYMUS
- LUNGS (lung bud)
LOWER SECTION of foregut:
primordial
- LIVER (liver bud)
- PANCREAS
when do we get development of the LIVER PRIMORDIUM / LIVER BUD
MIDDLE of 3RD WEEK
- appears as an outgrowth of
the ENDODERMAL EPITHELIUM at the distal end of the foregut
what plays a crucial role in INDUCTION of LIVER PROGENITOR CELLS (HEPATOBLASTS)
CARDIOGENIC MESODERM
what plays a crucial role in INDUCTION of LIVER PROGENITOR CELLS (HEPATOBLASTS)
CARDIOGENIC MESODERM
by providing extracellular signals
LIVER BUD CELLS differentiate into
PARENCHYMA (HEPATOCYTES)
haematopoietic cells, Kupffer cells and
connective tissue cells are derived from
MESODERM
Majority of the LIVER is derived from which germ layer
ENDODERM
but some from MESODERM (hepatic mesenchyme)
the PANCREAS is formed from 2 BUDS:
- DORSAL PANCREATIC BUD
- VENTRAL PANCREATIC BUD
the PANCREATIC BUDS (dorsal, ventral) originate from the ENDODERMAL LINING of the…
DUODENUM
which PANCREATIC BUD forms the UNCINATE PROCESS
VENTRAL PANCREATIC BUD
the VENTRAL pancreatic bud forms… (2)
- the UNCINATE PROCESS
- the VENTRAL PANCREAS / inferior part of the head of the pancreas
the rest of the pancreas is derived from the DORSAL PANCREATIC BUD
when do the pancreatic ISLETS OF LANGERHANS develop
3RD MONTH of embryonic development
when does INSULIN secretion begin
5TH MONTH
when does development of the RESPIRATORY DIVERTICULUM (LUNG BUD) take place
approx 4 WEEKS
- develops as an outgrowth from the
VENTRAL WALL of the foregut
Which parts of the RESPIRATORY SYSTEMare of ENDODERMAL origin
Epithelium of the internal lining of the larynx,
trachea,
bronchi
lungs
cartilaginous, muscular and connective tissue components of the trachea and lungs are derived from..
SPLANCHNIC MESODERM surrounding foregut
Lung bud EXPANDS CRANIALLY and 2 ridges appear and fuse:
TRACHEOESOPHAGEAL RIDGES
when TRACHEOESOPHAGEAL RIDGES FUSE what is formed
TRACHEOEPHAGEAL SEPTUM
TRACHEOEOPHAGEAL SEPTUM DIVIDES FOREGUT into :
Dorsal:
OESOPHAGUS
Ventral:
TRACHEA
& LUNG BUDS
4 stages of lung maturation:
- Pseudoglandular Period (6-16 weeks)
- Canalicular Period (16-26 weeks)
- Terminal Saccular Period (26 weeks to birth)
- Alveolar period (32 weeks to 8 years)
DERIVATIVES of the ENDODERM
- Digestive tract
- Epithelial lining of the respiratory tract
- Essential tissues of the thyroid, parathyroid, liver and pancreas
- Connective tissues of thymus and tonsils
- Epithelial lining of urinary bladder, urethra, tympanic membrane and auditory tube
Until the end of the 4th week,
the NEURAL TUBE is…
OPENED at the cranial and caudal NEUROPORES
BY DAY 24,
what appears as a result of EMBRYO GROWTH and FOLDING
PHARYNGEAL ARCHES appear
(arch-shaped FOLDS in the throat area)
due to rapid growth, the 3rd and 4th pharyngeal arches appear by day 28
How many PHARYNGEAL ARCHES are there in humans:
5
1,2,3,4 and 6 SIX
(no. 5 regresses almost immediately)
what is the name of PHARYNGEAL ARCH 1
MANDIBULAR ARCH
has 2 prominences:
- MAXILLARY 1
- MANDIBULAR 1
Which two PHARYNGEAL ARCHES FUSE
4 and 6