Human Embryonic development Flashcards
Which time is baby very sensitive?
4th,5th week in 1st trimester
What is gametogenesis?
Production of male and female gametes from primordial germ cells
When does spermatogenesis start?
Puberty
Where does spermatogenesis occur?
In seminiferous tubules of testes
When does oogenesis occur?
From fetal life in female
Where does oogenesis occur?
In ovary
What is a stem cell?
Undifferentiated cell that has ability to form specialised cell types
Pluripotent cell
Ability to form all mature cell types in body except placental and extraembryonic cells - cannot form whole organism
Multipotent cells
Ability to form more than one closely related mature cell types in body but not as varied as pluripotent cells e.g. cord blood/bone marrow stem cell form erythrocyte, leucocyte, platelet (blood related cells)
Totipotent cells
Ability to form all different cell types in body including placental and extraembryonic membrane cells- can form whole organism
Fertilisation meaning
Process by which male and female gametes fuse to form zygote
Where does fertilisation occur?
Occur at ampullary region of uterine tubule (oviduct)
What are the phases of fertilisation?
Penetration of corona radiata
Penetration of zona pellucida
Fusion of oocyte+sperm cell membranes
What is released to stop other sperm from binding?
The zona pellucida releases Ca granules to prevent other sperm from binding
What is capacitation?
physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg
What is the acrosome reaction?
Leads to release of enzymes needed to penetrate zona pellucida
Induced by zona proteins following sperm binding to zona pellucida
The sperms contact with plasma membrane of oocyte leads to release of what?
Lysosomal enzymes from cortical granules in plasma membrane
Changes permeability of zona pellucida, means no other sperm can bind to egg
What is cleavage of zygote?
Repeated series of rapid mitotic cell divisions of the large zygote
From zygote to blastomere
Cleavage transforms the zygote into sold ball of cells=morula
What is the main purpose of cleavage?
To go from zygote to morula
What is a morula?
Solid ball of 12-16 cells following cleavage
What is a blastocyst?
Stage when morula develops a inner cell mas enclosed by trophoblast
What is parthenogenesis?
Process where unfertilised egg develops into new individual
The blastocyst then develops into what?
Outer + inner layer names
Bilaminar germ disk:
outer layer= epiblast
inner layer= hypoblast
What is the primitive streak?
Thickened midline structure at caudal end of epiblast of bilaminar germ disc- form on day 15
