MODULE 1 : EMBRYONIC PERIOD Flashcards
Basis of Pregnancy Test. Secretion begins as early as 8 days postovulation.
HUMAN CHORIONIC GONADOTROPHIN
- continuous multinucleate layer of protoplasm
- secretes lactogen, estrogen, progesterone, HCG
SYNCITIOTROPHOBLAST
Composed of :
- extraembreyonic mesoderm
- cytotrophoblast
- syncitiotrophoblast
CHORION
Site of origin of primordial germ cells
YOLK SAC
Thickened circular area in the hypoblast
PRECHORDAL PLATE
Future site of mouth
OROPHARYNGEAL MEMBRANE
Future site of Anus
CLOACAL MEMBRANE
Process by which three germ layers are established
GASTRULATION
First sign of Gastrulation
FORMATION OF PRIMITIVE STREAK
Thickening of the medial plane of the epiblast starting at the caudal end
PRIMITIVE STREAK
Cranial end of streak proliferates to form what?
PRIMITIVE NODE
A disease wherein there is a remnant of the primitive streak
SACROCOCCYGEAL TETRATOMA
Forms the epidermis of skin, L.E. of mouth and rectum, cornea and lens of eye
ECTODERM
Forms the notochord, skeletal, muscular, excretory, circulatory and lymphatic systems, dermis of skin
MESODERM
L.E. of digestive tract, respiratory system, urethra, UB, reproductive system
ENDODERM
A cellular rod that develops from the notochordal process
NOTOCHORD
Indicates future site of vertebral bodies
NOTOCHORD
Small out-pouching from the caudal wall of the yolk sac which functions for :
- respiration
- urine reservoir
- assoc. with the development of UB
ALLANTOIS
Thickening of the embryonic ectoderm overlying the notochord
NEURAL PLATE
Infolding of the neural plate
Formation of NEURAL TUBE
Primordium of the CNS
NEURAL TUBE
Formation of the Neural Tube
NEURULATION
Differentiates and begins to divide into paired cuboidal bodies and gives rise to axial skeleton and skeletal muscles
PARAXIAL MESODERM
Gives rise to genitourinary system
INTERMEDIATE MESODERM
Gives rise to intraembryonic coelom
LATERAL PLATE MESODERM
Gives rise to the axial skeleton and its associated musculature
SOMITES
First organ to reach a functional state
CARDIOVASCULAR SYSTEM
Heart begins to beat during 3rd-4th week
All major organs and systems of the body form from three germ layers
ORGANOGENETIC PERIOD
Occurs when there is a failure of progression of the body folding
BODY WALL DEFECTS
Herniation of abdominal contents directly into the amniotic cavity
GASTROSCHISIS
First hematopoietic organ, role in transfer of nutrients to embryo
YOLK SAC
Persistence of yolk sac
ILEAL DIVERTICULUM (Meckel Diverticulum)
A division of Primitive gut which extends from the oropharyngeal membrane to the liver outgrowth (supplied by Celiac Trunk)
FOREGUT
Division of Primitive Gut which forms part of the liver outgrowth to the junction of the Right 2/3 and Left 1/3 of transverse colon (supplied by Superior Mesenteric)
MIDGUT
A division of the Primitive Gut from the left third of the transverse colon on the cloacal membrane (supplied by inferior mesenteric)
HINDGUT
Site of primordium of kidneys
MESONEPHRIC RIDGE
EMBRYONIC PERIOD : appearance of mesonephric ridge
FIFTH WEEK
EMBRYONIC PERIOD : formation of extremities (upper limbs develop first)
SIXTH WEEK
Primordium of external auditory canal
AURICULAR HILLOCK
EMBRYONIC PERIOD : Heart prominence
SIXTH WEEK
EMBRYONIC PERIOD : development of auricular hillock
SIXTH WEEK
EMBRYONIC PERIOD : ossification of bones of upper limbs
SEVENTH WEEK
EMBRYONIC PERIOD : has distinct human characteristics but head is still half of embryo size
EIGHTH WEEK
EMBRYONIC PERIOD : Start of development of external genetalia
EIGHTH WEEK
EMBRYONIC PERIOD : formation of morula
FIRST WEEK
EMBRYONIC PERIOD : start of implantation
FIRST WEEK
EMBRYONIC PERIOD : embryoblast forms two layers
SECOND WEEK
EMBRYONIC PERIOD : formation of primary yolk sac
SECOND WEEK
EMBRYONIC PERIOD : formation of Chorionic Cavity
SECOND WEEK
EMBRYONIC PERIOD : Gastrulation
THIRD WEEK
EMBRYONIC PERIOD : Neurulation
THIRD WEEK
EMBRYONIC PERIOD : formation of three germ layers
THIRD WEEK