Teratology-science dealing w/ causes, mechanisms, & manifestations of devo deviations, either structural, or functional
this science involves recognizing the patterns of abnormalities and keeping track of pregnancy exposures
Teratogen-acts on somatic cells of developing organism
Mutagen-acts of the germ cells, altering genetic material-it’s the one that’s inherited…
If you take out an environmental agent out of the [...]
The first somites appear on day 20 in the region of the future base of the skull
the 8th, 9th, and 10th somitomeres differentiate into the first, second, and third pairs of somites on day 20.
The rest of the somites form in cranial/caudal progression at a rate of about three or four a day.
[...]
Embryology of the Orbit
Development - 4th week, hox genes, pax 6
Derived from 4 sources :
Neuroectoderm of forebrain
Surface ectoderm of the head
Mesoderm b/t the above layers
Neural crest / [...]
Neurons store and process info (can conduct action potential)
Glial cells provide structural and metabolic support
CNS -> Brain & Spinal Cord
Brain -> Medulla, Pons, Cerebellum, Midbrain, Diencephalon, Cerebral Hemispheres
[...]
Fertilization and Implantation:
Capacitation: a period of conditioning that occurs in the female reproductive tract, must happen in order for sperm to fertilize the ovum.
Cortical Reaction: impermeability to other sperm
Acrosome Rxn: fusion of the outer acrosomal mem. and sperm cell membrane
Fertilization [...]
Formation of the Vasculature
vascular system begins early
it would be good for it to function early since the embryo is getting too large to depend only on diffusion for nutrients
should see a primitive heart beat between 18-21 days–(this is before folding)
The whole circulatory system is one way
cardiac tubes work in peristaltic [...]
after folding, the digestion tube is divided into foregut, midgut, and hindgut
The respiratory diverticulum begins as an outgrowth of the foregut(this appears day 22)
has splanchnopleuric covering
lower respiratory forms from endoderm and splanchnopleuric mesoderm
There’s a pharyngeal fold that forms out as a diverticulum
two buds grow out-dichotomous branching-forms the tracheobronchial tree
[...]
Male system-one part of the preserved urinary system
Functionally, mesonephros functions for only a short period of time-contributes to amniotic fluid by minimal urine contribution
Metanephric-provision of dilute urine to the amniotic fluid-this fluid is very important for proper development
Pronephros/Pronephric Kidney
starts developing by 21 days and already begins to degenerate by 28
begins a few cervical [...]
After folding, endoderm is still connected to yolk sac via yolk stalk..
yolk stalk = vitelline duct = omphalomesenteric duct
Yolk stalk-marks the place known as MIDGUT
NOTE: pharynx is the most rostral portion of foregut
Foregut-supplied by the celiac artery
Midgut-supplied by the superior mesenteric artery
Hindgut-supplied by the inferior mesenteric artery
We like to think that the rotation of [...]
Introduction
Outer ear transmits sound from the world to the middle ear
Inner ear produces electrical impulses both for sound
Important Concept: ear develops backwards: inner ear first, then middle, then outer ear
Development of the inner ear starts with a patch of ectoderm-these cells eventually become [...]
Esophageal Anomalies
Atresia - failure to recanalize lumen
- associated w/ tracheoesophageal fistula
- results in polyhydramnios due to inability to swallow (embryo)
- * VACTERL Association
- Type C most common: distal tracheoesophageal fistula and proximal atresia
- Inability to pass feeding tube into stomach
- Early surgical repair
Stenosis - narrowing of lumen
- Incomplete recanalization
Short Esophagus - failure to lengthen
- results [...]
Initial events with the heart happen as early as the middle of the 3rd week.
§ The trilaminar disk in its flat form, there’s a region towards the cephalic end, the cardiogenic region that will develop into the region that will be the heart.
§ On Day 19, 2 very thin walled tubes develop one on either [...]
FORAMEN CECUM-pit of endoderm at the junction of the derivatives of the 1st and 2nd arch-this goes out into the mesenchyme to for, THYROID GLAND
Cephalization-this action pushes everything forwards-helps explain recurrent laryngeal nerve
In the case of the recurrent laryngeal, looks like it starts where 4th branchial arch is, then cephalization pushes it forward such [...]
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