Early Embryology Week 3 Flashcards
What is ovulation and when does it occur?
1 mature oocytes is released from the ovary and swept into the oviduct. This occurs 2 weeks into the ovulation cycle.
What are synonyms for oviduct?
Fallopian tube, uterine tube
Where in the fallopian tube does fertilization take place? Describe its location.
The Ampulla is the location where fertilization takes place and it is the wide distal portion of the oviduct.
The oocyte is now in the ampulla of the fallopian tube. Sperm will travel from the _______ to the _______. It takes ______ to ________ for the sperm to travel.
cervix to the fallopian tube , 30 minutes-6 days. If the egg hasn’t been released into the oviduct, the sperm can stay in the ampulla for up to 6 days.
From exterior to interior, describe the three linings of the uterus. Which one is the thickest during ovulation?
Perimetrium, Myometrium, Endometrium. The endometrium is the thickest.
What is myometrium made of?
Smooth muscle
What is the coat on the outside of the egg called? When does it exist?
The Zone of Pellicuda is a sperm barrier that is bypassed only during fertilization. It will disintegrate when the blastocyst reaches the uterus.
When the male and female pronuclei come together, what are they called? What is the number of chromosomes in the gamete and in the ______?
Zygote. Gametes have n and Zygotes have 2n.
What does fertilization result in?
Diploid chromosomes, Gender Determination and cleavage is initiated
What is XX?
Female
What is XY?
Male
Within what time period does the sperm have to meet the egg in order for fertilization to occur once the egg is swept into the ______?
24 hours, ampulla
What happens to the zygote after fertilization? Zygotes are ___- cell stage.
The zygote rapidly divides via mitosis.
What are the 3 stages of zygote division and how many cells are in each stage?
- Zygote- 2 cell
- 4-Cell
- Morula-16 cell
When does the advanced morula enter the uterine cabin?
4 days after fertilization
What happens to the morula after it enters the uterine cabin? What is the name of the structure? How long does it take to form.
Cells continue to replicate and the “ball” of cells forms a fluid filled center surrounded by the cells. This is called a blastocyst and forms 5 days after fertilization. (About 1 day after morula enters the uterine cabin)
What happens to the blastocyst? What 3 structures are apparent at this stage?
Some cells of the blastocyst congregrate into an inner cell mass called the EMBRYOBLAST.
Other cells form a ring around the blastocyst called TROPHOBLASTS that provide nutrition for the embryo.
A BLASTOCOELE , a fluid filled cavity, forms.
What does trophoblast layer eventually turn into?
Placenta
What is implantation and when does it occur?
The morula/blastocyst is pushed along the fallopian tube until it enters the uterus about 6-7 days after fertilization.
Abnormal implantation can occur. Which location of implantation can cause placenta previa?
Implantation in the cervix, inferior to the uterine cavity can cause placenta previa because placenta is blocking the cervical opening preventing vaginal birth.