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 [...]
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 [...]
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 / mesechyme cells Optic groves appear in the neural folds at the cranial end of the embryo. Then these optic grooves→ optic vesicles. The [...]
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 CNS protected by skull and vertebral column and 3 meninges (dura mater, arachnoid, pia mater) CSF made in ventricles [...]
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 in ampulla of fallopian tube Day 3 = Morula enters the [...]
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 [...]
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 [...]
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 [...]
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 [...]
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 [...]
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 [...]
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 [...]
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 [...]
