Embryonic Development Flashcards
Parthenogenesis
Development is initiated by the egg without fertilisation
Mus musculus
mouse
Gallus gallus
chick
Danio rerio
Zebrafish
Caenorhabditis elegans
nematode
Tribolium castaneum
red flour beetle
Bombyx mori
silk moth
Hox genes
Anterior-posterior patterning
Pax6
Eye develpment
Chordin/BMP
Neural development
Xenopus laevis
Clawed frog
Isolecithal eggs
Small and have little yolk evenly disributed in cytoplasm
Mesolecithal eggs
Large eggs with moderate to large amounts of yolk that is localised ot one half of egg
Telolecithal eggs
Moderate to large amounts of yolk that fill cytoplasm except for small area near animal pole
Centrolethical eggs
Yolk concentrated in centre with a peripheral layer of yolk free periplasm
In amphibians animal hemisphere is
darkly pigmented
In amphibians vegetal hempishere is
lightly pigmented
Mid-piece in spermatozoa contains
The base of the flagellum
Hydatidiform moles
Either diploid with only male chromosomes or triploid with two copies of male chromosomes and 1 copy of female chromosomes
Egg is surrounded by a membrane known as
Zona pellucida
Cortical reaction to fertilisastion
Prevents polyspermy by modifying ZP3 receptor
Holoblastic cleavage
Isolecithal and some mesolethical eggs and involves complete cleavage of egg
Trophoblast
Blastomere epithelium
Blastocoel
Cavity in the centre of embryo
Inner cell mass
Small population of non-trophoblast cells found at one end of the blastocoel
Morula
After 5th horizontal cleavage 4 tiers of 8 cells
Blastula
When cleavage becomes more variable
Meroblastic cleavage
Telolecithal and centrolecithal eggs with large amounts of yolk where complete cleavage is difficult
Discoidal cleavage
Only a small yolk free portion of egg is cleaved typically at animal pole
Superficial cleavage
Male and female haploid nuclei fuse deep within yolky centre of egg where first 9 nuclear divisions occur
Mid-blastula transition
The switch from cell divisions without gap phases to ones with gap phases
Gap phases
allow genome to be transcribed and to replace maternal transcripts which are gradually destroyed
Mesodermal cell types
Connective tissue, Muscle, Dermis + subcutaneous layer Skeleton, kidneys, adrenal cortex
Endodermal cell types
G.I. tract, liver, pancreas, endocrine glands, auditory system, urinary system
Ectodermal cell types
Epidermis, nervous system, pigment cells
Germinal vesicle
Describes eggs in animal hemisphere
Nodal is a TF
required for mesoderm formation
Vitellagen forms ____%
90% of xenopus egg
Brachyury
Formed in mesoderm of all chordate embryos: early cell fate and regulate gastrulation
Skeletal muscle expresses
Myosin II, Titin, MyoD1
Smooth muscle expresses
BMP
Neural plate folds _____ to form
Neural tube
Primitive node -> _______ -> _________
Mesoderm, Neural plate
Neural plate has ___________ epithelium
Pseudostratified columnar epithelium
Mesoderm can be induced in an isolated cap by
Activin, Nodal , FGF4
Insect eggs are held at ____ of meiosis
Metaphase I
Mammalian eggs are held at ____ then ____ of meiosis
Prophase I then Methaphase II during ovulation
Andromorphs
Only male chromosomes: abnormal growth of placental tissues and no discernable embryo
Gynomorphs
Only female chromosomes : poorly developed placental tissue and poorly formed embryo
Genetic Imprinting
DNA + associated histone proteins are officially modified during gametogenesis so associated genes are inactive during development
Disorders associated with genetic imprinting
Angelman, Beckwith-Wiedenem, Prader-Willis, Silver-Risa
Cell cycle length may be controlled by ratio
of DNA to cytoplasm