Embryonic Period 3-8 Weeks Flashcards
Teeth enamel is derived from what germ layer
Ectoderm
Forelimbs paddle-shaped;
Nasal pits formed;
Embryo tightly C-shaped
Day 31-35
Parathyroid derived from what germ layer
Endoderm
Develops from somites
Bone, cartilage, muscle, dermis of the skin
Central nervous system is derived from what germ layer
Ectoderm
Sensory epithelium (ear, nose, eye) is derived from what germ layer
Ectoderm
Dermatome (tissue)
Dermis of the skin
Embryonic period (day 24-25) number of somites
13-20 somites
Respiratory tract epithelial lining derived from what germ layer
Endoderm
Embryonic epiblast produces what
Primitive streak
Ectoderm
Mesoderm
Primordial germ cells
Endoderm
Fourth visceral arch formed;
Hind limb buds appear;
Otic vesicle and lens placode
Day 28-30
GI tract epithelial lining derived from what germ layer
Endoderm
Embryonic period (day 28-30) number of somites
30-35 somites
Digital rays in hand and foot plates;
Brain vesicles prominent;
External auricle forms from auricular hillocks;
Umbilical herniation intiated
Day 36-42
Number of somites that appear during Day 20-21
1-4
Auditory tube epithelial lining derived from
Endoderm
Pancreas derived from what germ layer
Endoderm
Day(s) the notochordal process appears
Day 16-18
Tympanic cavity epithelial lining derived from
Endoderm
Embryonic period (day 20-21) number of somites
1-4 somites
Embryonic period (day 26-27) number of somites
21-29 somites
Connection with yolk sac and placenta maintained through
Vitelline duct and umbilical cord, respectively
Skin, hair, nails is derived from what germ layer
Ectoderm
Liver derived from germ layer
Endoderm
Limbs long, bent at elbows, knees; Fingers, toes, free; Face more human like; Tail disappears; Umbilical herniation persists until the end of the third month
Day 50-56
Somites appear
Day 20-21
Embryonic period (day 22-23) number of somites
5-12 somites
Intraemryonic mesoderm spread under cranial ectoderm;
primitive streak continues;
umbilical vessels and cranial neural folds begin to form
Day 19-20
Notochordal process appears;
hemopoietic cells in yolk sac develop
Day 16-18
Somitomeres are formed from
Paraxial mesoderm
Day(s) the primitive streak appears
Day 14-15
Connective tissue and bones of the face and skull derived from
Neural crest (ectoderm)
Caudal neuropore closing or closed;
Upper limb buds appear;
Three pairs of visceral arches
Day 26-27
Cephalocaudal folding under way;
cranial neuropore closing or closed;
optic vesicles formed;
otic placodes appear
Day 24-25
Pituitary gland derived from what germ layer
Ectoderm
neural tube (posterior pituitary) / outer epithelium (anterior pituitary)
Mammary and sweat glands are derived from what germ layer
Ectoderm
Three components of the mesodermal germ layer
Paraxial, intermediate, lateral plate
Three supporting tissues produced by somites (paraxial mesoderm)
Myotomes
Sclerotomes
Dermatomes
Cranial neural folds elevated and deep neural groove established; embryo begins to bend
Day 20-21
Myotome (tissue)
Muscle tissue
Neural tube failure (cranial region)
Anencephaly
Part of pituitary gland is derived from the neural tube of the ectoderm
Posterior pituitary
Fusion of neural folds begins in cervical region;
cranial and caudal neural folds open widely;
visceral arches 1 and 2 present;
heart tube begins to fold
Day 22-23
Urinary bladder epithelial lining derived from what germ layer
Endoderm
Mesenchyme of the head derived from
Somitomeres (paraxial mesoderm)
Parenchyma of the thyroid derived from what germ layer
Endoderm
Pigmentation of retina visible; Digital rays separate; Nipples and eyelids formed; Maxillary swellings fuse with medial nasal swellings as upper lip forms; Prominent umbilical herniation
Day 43-49
Neural tube fails to close (cervical region caudally)
Spina bifida
Sclerotome (tissue)
Cartilage and bone
Peripheral nervous system is derived from what germ layer
Ectoderm