Intro to Embryology Flashcards
preembryonic phase weeks
0-3 weeks
embryonic phase weeks
4-8 weeks
foetal phase weeks
9-40 weeks
what occurs in week 1 of preembryonic phase
zygote is formed, divides to form blastocyst, moves through uterine tube to reach uterine cavity
mitchondrial diseases are inherited from
mother because only eggs contribute mitochondria to the next generation
solid ball of cells following mitosis is called
morula
why does morula turn into blastocyst
the inner cells of a morula cannot get nutrition so the blastocyst is formed in order to get them the nutrition they need using the trophoblast, inner cell mass and blastocyst cavity structure
where does blastocyst formation occur
uterine cavity where it implants into endometrium
how does ovum or fertilised ovum move through Fallopian tube
ciliated epithelium beat the ovum to move it to uterine vanity
ectopic pregnancy
ovum implants somewhere outside of the uterine cavity due to inflammation in the uterine tube which prevents the function of the ciliated epithelium
what occurs in week 2 of preembryonic phase
implantation occurs in uterine endometrial layer and placenta begins to develop, cells that later form the embryo form a bilaminar disc, sacs, membranes and cord to nourish the baby start to form
trophoblast divides to form two layers which ultimately forms a
chorion which has finger like projections called chorionic villi
functions of chorion
implantation process, forms part of placenta in due course and secretes human chorionic gonadotropin HCG which is used to detect pregnancy
endometrium with implanted conceptus
decidua
what happens to inner cell mass in week 2
form a 2 layered flat disc called the bilaminar disc so that 2 cavities now begin to form -amniotic cavity and yolk sac
functions of placenta
foetal nutrition, transport of waste and gases, immune system
what type of twins share placenta
monozygotic, identical. same genetic makeup and one placenta
primitive streak
formed in the midline of the epiblast in week 3 by the dipping in of cells and once the primitive streak is formed, the axis of the embryo is formed
3 germ layers
ectoderm, mesoderm, endoderm
how is trilaminar disc formed and name of the process
epiblast cells migrate to inbetween the epiblast and hypoblast and then displace the hypoblast to form three germ layers and cells are now specialised.
name of the process of how trilaminar disc formed
gastrulation
what is neural tube formation called
neurulation
how is neural tube formed
cells from ectoderm sink down to form a solid tube, release notochord then neural plate is formed in the ectoderm, those neural plates sink down to form neural tube which causes crests to form on surface which eventually join which is induced by the notochord
what happens to mesoderm after neurulation
thickens and then separates into three parts
three parts of mesoderm
paraxial mesoderm, intermediate plate mesoderm, lateral plate mesoderm (which splits)
where are somites formed
paraxial mesoderm
somites are split into 3 which are
dermatome, myotome, sclerotome
what happens after somites formed and split
lateral folding and the lateral plate mesoderm that split joins with other split at end in C shape
endoderm forms what
gut and respiratory system
lateral plate mesoderm forms what
peritoneum, pleura, body cavities
intermediate plate mesoderm forms what
urogenital system eg kidneys and reproductive
ectoderm forms what
epidermis of skin and neural tube
paraxial mesoderm forms
dermatome (dermis), myotome (muscles), sclerotome (bones)
teratology
study of when things go wrong during development
teratogens
environmental factors that cause abnormal development
period of greatest sensitivity to teratogens
weeks 3-8
period of greatest sensitivity to teratogens
weeks 3-8
