M2-Lecture1 Flashcards
(144 cards)
ePreconception period is:
Period preceeding, including and immediately following human conception.
Prenatal period
Fertilization has occured and zygote is formed
Period between conception & birth
Perinatal period
Period immediately before and after birth.
Which trimester includes important developmental milestones and give examples:
First
Fertilization, pre-embryonic & embryonic period.
In first trimester basic structure of organs and tissues forms, what is this called?
Organogenesis
First trimester name of the developing baby:
Second trimester and third trimester: Fetal
Embryonic
What are finger-like projections that help guide the egg from the ovary into the fallopian tube after ovulation facilitating the meeting of egg & sperm for fertilization:
Fimbria
On what day after fertilization does the morula become blastocyst (dividing cells with central cavity filled with fluid - blastocoel:
Fifth day
What is a solid ball of cells that forms after the fertilization of an egg and the first few rounds of cell division, and is surrounded by ZP (16 cells)?
Morula
What does the blastocyst form into:
- Trophectoderm (outer layer): Placenta (trophoblast cells) & fetal membranes.
- Inner mass at one pole that will form the embryo
Fluid filled cavity (overall structure and deve. of embryo)
What is the outerlayer of the blastocyst?
Trophectoderm
What do uterine secretions provide to the blastocyst following the multiplying of the inner & outer cell masses:
Oxygen & metabolic substrates
Because the uterine secretions are inadequate, that’s why within 24 hours of hatching or day 6 after fertilization, the blastocyst implants in uterine lining, which has access to glycogen filled stromal cells (which supply nutrients). T/F
True
Gylcogen filled stromal cells are necessary for continued growth. T/F
True
Sperm can remain in the uterus for several days?
Yes
Sperm penetration causes zona pellucida to become impermeable by other sperm. what is this called?
Cortical reaction
How does sperm penetrate the ZP:
Acrosome of sperm binds to ZP, specifically ZP3 protein. Enzymes hyaluronidase and acrosin are released.
These enzymes help the sperm penetrate the ZP.
What fast block of the ploysperms?
Depolarization of egg’s membrane
The slow block involves:
Cortical reaction, where cortical granules release substances that modify ZP
Zygote fusion of two gametes, 46 chromosomes, divides by:
Mitosis
When does implantation occur:
By the end of first week. Blastocyst implants in uterine lining.
When the inner mass cell forms two-layered disc of embryonic cells, what is the fluid filled component btw. it & the trophoblast?
Amniotic cavity
Briefly explain what occurs during embryonic week 2 (GA week 4) development - early stages of embryonic deve.:
- Inner cell mass forms two-layered disc of embryonic cells (Bilaminar embryonic disc)
Upper Layer: Epiblast
- Develops into amnion, which fill with amniotic fluid
- Also forms the embryo.
Lower Layer: hypoblast
- Forms the yolk sac
What does the amniotic fluid contain?
Initially maternal plasma & later fetal urine.