Embryology Introduction Flashcards
Pre-embryonic phase
0-3 weeks
Embryonic phase
4-8 weeks
Foetal phase
9-40 weeks
Spermatogenesis
Production of 4 sperm from spermatogonium, only starts after puberty
Oogenesis
Production of 1 ovum from oogonium, meiosis I when embryo, meiosis II after puberty
Product of fertilisation
Zygote
Fertilisation
Pro-nucleus of sperm enters and fuses with the pro-nucleus of ovum
Week 1
Zygote formed and divides to from blastocyst, moves through uterine time to reach uterine cavity
Zygote divides to form a solid ball of cells called the
Morula
Mitochondria are passed on from the
Mother
What is formed once the number and size of cells of morula increase
Blastocystic cavity - blastocyst
In blastocystic cavity, cells accumulate at one end to form an
Inner cells mass
The outer lining of cells of blastocystic cavity is called the
Trophoblast
Cell lining Fallopian tube to help with movement
Ciliated epithelium
What could occur if cilia function in fallopian tube is abnormal
Ectopic pregnancy (fertilised egg implants itself in Fallopian tube)
Blastocysts in implanted in the
Uterine cavity
Week 2
Implantation occurs, placenta begins to develop, bilaminar disc is formed, sacs membranes and cord start to form
Trophoblast divides to form
Chorion
Chorionic villi
Finger like processes of chorion
Chorion function
Implantation, forms part of placenta, secretes human chorionic gonadotropin (HCG)
Decidua basalis
Part if endometrium deep to the implanted conceptus
HCG
Maintains endometrium
Cells of inner cell mass form a 2-layered disc called the
Bilaminar disc
2 cavities formed by bilaminar disc
Amniotic cavity and yolk sac
2 cell layers forming bilaminar disc
Epiblast and hypoblast
Function of yolk sac
Provide nutrition
Allantonic cavity
Accumulates waste material
Chorionic cavity
Holds embryo