Chapter 5 & 6 Flashcards
Greek for the little stomach
Grastula
Caudal migration of epiblasts forms the ______ at the caudal midline of the blastocyst.
primitive streak
Composition of Primitive Streak
Hensen’s node (primitive node or primitive knot)
Primitive groove (central depression)
Primitive folds (lateral elevations)
What are the 3 primary germ layers?
Ectoderm, Mesoderm, Endoderm
What happens to the remaining epiblasts of the primitive streak?
Give rise to ectoderm
Migrating cells from primitive streak entering the coelom will become ______
Mesoderm
Which germ layer forms the epidermis of skin, epithelium of oral and nasal cavities, nervous system and sense organs?
Ectoderm
Which germ layer forms the muscles, connective tissues including bones and components of circulatory, urinary and genital systems?
Mesoderm
Which germ layer forms the mucosal epithelium and glands of respiratory and digestive systems?
Endoderm
When does the primitive streak in avian embryo reach its maximum length?
18 hours of incubation
Continuous migration of epiblast from the primitive streak and non-addition of new epiblasts to the primitive streaks results to ________
regression of primitive streak
Primitive streak of avian embryo disappears by _________ of incubation
60 hrs (2.5 days)
True or false in most primitive vertebrates the notochord is the chief axial supporting structure of the body.
True
True or false the formation of notochord induces the formation of the head, nervous system and somite.
True
True or false the formation of notochord does not indicate the future location of vertebral column in higher vertebrates.
False
What is the ultimate fate of the notochord?
Nucleus pulposus of intervertebral disc.
What is the Morphogenic process that gives rise to the 3 primary germ layers: ectoderm, mesoderm and endoderm?
Gastrulation
What is the stage of early embryonic development characterized by early development of CNS, formation of the head process and foregut, formation of somites and formation of cardiac tube?
Neurulation
The depressed midregion of the neural plate is called
neural groove
The raised edges at the neural plate
neural folds
Cavity of neural tube
neural canal
Bilaterally some cells from neuroectoderm excluded during fusion of neural folds lie dorsolateral to the neural tube and constitute the ________
neural crest
The neural tube give rise to _______
CNS, brain and spinal cord
development of 2 or more embryos in a dam that normally gives birth to
one offspring per gestation.
embryonic Duplication or Twinning
result from fertilization of separate ova.
Free separate symmetrical dizygotic or polyzygotic twins
from two separate zygotes.
Dizygotic twins
similar to dizygotic twins except that the number of zygotes is more than two.
Ex: triplets
Polyzygotic twins
derived from a single zygote
Free or conjoined, symmetrical, monozygotic twins
the zygote duplicates itself and the twins separate completely.
Free symmetrical monozygotic twins or identical twins -
– the zygote incompletely divides.
Conjoined or fused symmetrical monozygotic twins
are identified according to the site of attachment
Diplopagus or Siamese twins
twins are attached at the sternal region facing each other with partially
fused hearts.
Thoracopagus
twins are attached at the abdomen, often with partially fused
intestines
Abdominopagus
twins are attached at the pelvis or sacrum back-to-back
Pygopagus
twins are attached in the head region.
Cephalopagus
abnormally fused symmetrical monozygotic twins where the axial structures are
duplicated
Monster
two heads
Dicephalus
two faces
Diprosopus
two tails
Dicaudatus
four thoracic limbs
Tetrabrachius
four pelvic limbs
Tetrascelus
originate from monozygotic or dizygotic twins. Has one normal and one rudimentary twin
Free asymmetrical twins
Fused twins with one normal individual called autosite and an extra body part, the parasite
attached to it
Conjoined asymmetrical twins
where an extra pelvic limb is attached to the back of the normal twin
Notomelus
elliptical region of specialized thickened ectoderm is referred to as
neural plate
neural folds continue to elevate, appose in
the midline, and, eventually, fuse to create the
neural tube
