Gastrulation Flashcards
Invagination
Folding of the surface epithelium of the blastula usually at the vegetal pole to form a central tube, archenteron
Blastopore
Point of invagination
Involution
Similar to invagination and also forms an archenteron that extends towards the animal pole from a blastopore
Ingression
Migration of individual cells from surface epithelium into the interior of the embryo
Primary mesenchyme cells
Apical surface of vegetal plate form bottle cells which ingress into blastocoel, remaining clustered at vegetal plate to form precursors of the mesoderm
Cadherins
Ca2+ dependent adhesion molecules
Convergent-extension
Cells become elongated perpendicular to axis of elongation and form actin and myosin rich lamellipodia at opposite poles. Lamellipodia used to exert traction on each other and drive cell intercalation narrowing invaginating tube and elongating towards animal pole
Secondary mesenchyme cells
Complete elongation of archenteron. Form at invaginating tip of archenteron and produce filopodia
Filopodia
Long cytoplasmic extensions that search for basal surface of animal pole§
Trophoblast
Outer epithelium at 16-32 cell stage of holoblastic cleavage, forms chronic layers of placenta
Inner cell mass
Small population of internal mesenchyme- like cells at 16 to 32 cell stage
First step in development of mammalian ICM
Formation of hypoblast and epiblast
Hybolast layer is adjacent to
Blastocoel
Heuser’s membrane
Layer of exraembryonic endoderm deriving from hypoblast spreading around trophoblast lining the blastocoel
Yolk sac
Enclosed cavity by Heuser’s membrane
Meckel’s diverticulum
Small bulge in the small intenstine and is most frequent congenital malformation of digestive tract
Amniotic membrane
Layer of flattened epithelial, extraembroynic ectoderm,cells lining amnion formed by epiblast
Synctiotrophoblast
Tissue formed when trophobolast is in contact with endometrium. Highly invasive and penetrates uterine walls, secreting enzymes that digest the extracellular matrix which normally surrounds and connects cells.
Cytotrophoblast
Trophoblast cells lining blastocoel in contact with ICM remaining a single layered cellular epithelium
Lacunae
Cavities in the synctiotrophoblast filled with maternal blood from uterine capillaries
HCG
Required to maintain progesterone production by the corpus luteum
Buccopharyngeal membrane
Formed by epiblast layer at future rostral pole
Cloacal membrane
Formed by hypoblast layer at future caudal pole
Primitive streak
Ridge of cells at midlien of caudal half of epiblast layer on 14th day
Node
Mould of cells at rostral end of primitive streak
Somites
Paired blocks formed progressively along rostral-caudal axis by paraxial mesoderm.
Anecephaly
Failure to close anterior neural tube causes brain degeneration and failure to form cranium
Spina bifida
Failure to close posterior end leads to severe paralysis
Pharyngeal arches
Cranial neural crest cells which differentiate as cartilage and bone migrate into ventral region of head
Phylotypic stage
Where vertebrate embryos are most similar
The ICM forms
tissues of fetus, amniotic membrane, yolk sac epithelium, vascalature of placenta and umbilical cord
The amniotic membrane is formed from the
Epiblast layer
The epiblast layers has ______ epithelium
Simple cuboidal
Chronic somatomammotropin
Maintains placental growth
Chronic thyrotropin
Regulates mothers metabolism
Chronic corticotropin
Regulates growth of mammary glands
Trophoblast blocks _______ by ______ antigen
Pregnancy termination by paternal antigen
Buccopharyngeal form
mouth
Cloacal
anus
Nucleus pulposus is the only area where
notochord is retained in inter-vertebral discs
Neural plate of ectoderm is formed at the
end of gastrulation
Apical constriction and convergent-extension is needed for
neural tube closure
Splachnic mesoderm is formed from
Embryonic folding
Krox20 is necessary for transcription of
Rhomborents 3 + 5
