Embryology

Front 1

Fetal Landmarks
(1) day 0
(2) w/in week 1
(3) w/in week 2
(4) w/in week 3
(5) week 3-8
(6) week 4
(7) week 10

Back 1

(1) day 0: fertilization
(2) w/in week 1: implantation as a blastocyst
(3) w/in week 2: "rule of 2s": 2 germ layer - epibalst & hypoblast; 2 cavities - amniotic cavity & yolk sac; 2 component of placenta - cytotrophoblast & syncytiotrophoblast
(4) w/in week 3: 3 germ layers (gastrula): 3ctoderm, mesoderm, endoderm
(5) week 3-8: most susceptible to teratogens b/c of organtonesis;
(6) week 4: heart begins to beat, upper+lower limb buds begins to form
(7) week 10: sexual differentiation

Front 2

Embryologic derivatives:
Ectoderm: surface ectoderm, neuroectoderm, neural crest

Back 2

Surface ectoderm: adenohypophysis, lens, epi lining, epidermis;

Neuroectoderm: neurohypophysis etc;

Neurocrest: chromaffin cells of adrenal medulla, Parafolliclular C cells etc

Front 3

Embryologic derivatives:
Mesoderm:

Back 3

dura, connective tissue, msucle, bone, CV structures, lymph, blood, urogenital, serous lining of body cavity (eperitoneal), spleem, adrenal cortex, kidney

Front 4

Embryologic derivatives:
Endoderm

Back 4

gut tube epi and derivatives (lung ,liver, pancreas, thymus, parathyroid, thyroid follicular cells)

Front 5

Embryologic derivatives:
Notochord

Back 5

induces ectoderm to form neuroectoderm (neural plate). Its postntal derivative is the nucleus pupposus of intervetebral disk