Early Human Development Flashcards
what is the firsts step of fertilisation
sperm binds with bona pellucida glycoprotein ZP3
what happens after the initial stage of fertilisation
enzymes from sperm
into egg
moms of both fuse
cortisol granule release from egg = fertilisation mem impenetrable by other sperm
what is he haploid gamete form
sperm penetrates egg also triggers completion of second meiotic div
what is a zygote
fusion of male and female pronuclei restores the diploid num of chromos
what surrounds zygote
zona pallucida
what ar blastomeres
smaller daughter cells - mitotic div of zygote
up to 8 cell stage what is said for the blastomeres
totipotent
what is totipotent
give rise to any cell in embryo and supporting tissues
when does a blastocyst form
4-5 days
so what does a zygote consist of
blastomeres
what is a morula
16 blastomeres
what happens to a morula
under goes compaction to form a blastocyst
what is compaction
forms blastocyst
formation of cell junctions smoothing outside
what is blastocyst hatching
zona pellucide breaks
blastocyst free float
what does the inner cell mass do
gives rise to embryo
r
what do the remaining cells do that are not forming embryo
form the trophoblast which contributes to placenta
what are the embryonic stem cells derived from
from ICM
what happens after blastocyst hatching
from zona pellucida
embryo interacts directly with endometrial lining of uterus
where are normal sites for implantation
middle or upper dorsal uterine wall
were are abnormal sites of implantation
ovary ampulla uterine tube lower uterus cervix peritoneum
what is an ectopic pregnancy
when implantation in abnormal site
what kind of process is implantation
active
what does the blastocyst interact with or implantation
maternal tissues
what happens in implantations at cellular level
trophoblasts divide and secrete subs break endometrial cell connections
cell processes to burrow into uterine walll
what happens after implantation
embryo blast
prod cells = cav = amniotic cav/mem
when does impacted embryo occur
9-12 days
what is a syncytiotrophoblast
placental villi, which invades the wall of the uterus, contacts maternal blood supply
where is the amniotic cavity presented
above bilayered embryonic disc and yolk sac below
what encircles entire embryo
chorionic cavity
what s the earliest indication of placenta
filled maternal blood sinusoids in trophoblasts has connections
what is gastrulation
most imp if doesn’t occur no further dev
formation of germ layers
what happens in gastrulation
2 layers become 3
what do cells migrate to in gastrulation
primitive streak
what do the additional cells do when they get to primitive streak
go inside and push apart bilaminar structure and form an additional middle layer
what are the 3 layers formed from gastrulation
endoderm
mesoderm
ectoderm
what is the endoderm
innermost layer
later form lining of gut
what is the mesoderm
middle layer
new
rise to muscle, bone and internal organs
what is the ectoderm
outermost layer
rise to nervous system and skin
what is neuralation
formation of neural tube
what is the first step of neuralation
an area of the ectoderm is induced to form neural tissue
what is the distinctive shape of neural tube
cranial end broader and caudal narower
at day 19/20 what happens to neural tue
neural tissue roll up itself and isnkinto body wall of embryo for protection
what happens to neural tube formation at day 23
has ant neuropore and post neuropore
cranial closes first
what does the neural crest do
undergo epithelial to mesenchymal transition and leave the neuroectodermtm enter the mesoderm
what are neural crest derivatives
scan cells and meninges DRG autonomic gang bones and CT of craniofacial melanocytes chromatin cells odontoblasts
how is a 3D embryo formed
cranial, caudal and lateral folding
what do pharyngeal arches do
develop in all vertebrates
contribute to much of face and neck
when do the diff arches form
1 = day 22
2 + 3 = day 24
4 + 6 = day 29
what does each arch consist of
core of mesenchyme - musculature of face and neck
neural crest cells - skeletal components of face
cranial nerve component
artery
what sp comes form arch 1
maxilla
mandible
zygomatic and temporal squamous bones
muscles of mast
what sp comes form arch 2
muscle facial exp
what forms upper and mid facial features
proliferating mesenchyme ventral to developing brain
what are the facial swellings
frontonasal prominence
nasal placode
maxillary prominence
mandibular prominence
what are the nasal swellings
frontonasal prom medial nasal swell lateral nasal swell max prom mand prom
