Embryology 1-3 Flashcards
Embryology is concerned with…
The study of embryos and their development
First stage in development of a foetus
Fertilisation
Thirty hours after fertilisation…
The fertilised egg splits (oocyte) into two segments called blastomeres
At 16 cells, the group of cells are referred to as…
The morula
Within the first week, the morula reorganises to form…
A cavity known as the blastocoel
The blastocyst consists of…
An outer cell mass (trophoblast) and inner cell mass (embryoblast)
The trophoblast of the blastocyst
Outer cell mass of blastocyst which contacts with endometrium of uterus to facilitate implantation
Embryoblast…
Inner cell mass of blastocyst which develops into the embryo
During the second week, the trophoblast develops into the…
Syncytiotrophoblast and cytotrophoblast
During the second week, the embryoblast develops into…
Epiblast and hypoblast - bilaminar disc
Within the epiblast forms the
Amniotic cavity
During implantation of an embryo…
The maternal blood vessels (sinusoids) invade the spaces (lacunae) of the syncytiotrophoblast
Placenta praevia
Where the embryo implants low down on the uterine wall - higher chance of haemorrhage
Week 3 of embryo development
Gastrulation
Gastrulation involves…
Migration, invagination and differentiation of the epiblast
Gastrulation is largely controlled by…
The primitive streak
Primitive streak structure
Primitive node at cranial (top) end. Primitive pit within primitive node
Cells break through primitive pit and migrate through epiblast to form…
Endoderm, mesoderm and ectoderm
Endoderm
Formed by cells which migrate through the pit and replace hypoblast cells
Mesoderm
Cells which migrate through the primitive pit and sit between epiblast and endoderm
Ectoderm
Formed by Epiblast cells which remain in position
Structures derived from endoderm
Epithelial lining of digestive and respiratory tracts, lining of urethra/bladder/reproductive systems, liver and pancreas
Structures derived from mesoderm
Notochord, musculoskeletal system, muscular layer of stomach/intestines, circulatory system
Structures derived from ectoderm
Epidermis of skin, cornea/lens of eye, nervous system
