23B: Development Flashcards
1
Q
prenatal development
A
- embryonic development (0-8 weeks)
- fetal development (9 weeks-birth)
2
Q
What is gestation and what major changes occur during each trimester?
A
- gestation: time spent in uterus
- 1st trimester: major systems develop
- 2nd trimester: body shape and proportions change
- 3rd trimester: largest weight gain, fully functional
3
Q
postnatal development
A
after birth development until maturity
4
Q
Describe the process of fertilization
A
- ovulation releases secondary oocyte
- fertilization and oocyte activation upon fusion of sperm and oocyte membrane (becomes ovum); rise in Ca2+ ensures only one sperm fertilizes egg
- male and female pronuclei form
- spindle fibres appear and cleavage starts
- male and female pronuclei fuse and cleavage of zygote begins
- cytokinesis begins; 1st cleavage forms two blastomeres
5
Q
Describe cleavage
A
- cytoplasm of the zygote gets divided among progressively smaller blastomeres
- blastomeres -> early morula -> advanced morula -> blastocyst
- implantation of blastocyst to endometrium
- trophoblast develops
- amniotic cavity forms
- yolk sac forms
6
Q
Describe gastrulation
A
- embryonic disc and its germ layers form
- superficial cells of blastodisc move toward central line and form ectoderm, mesoderm and endoderm
7
Q
Describe the stages of labor
A
- dilation stage: cervix dilates and contractions occur every 10-30 min
- expulsion stage: cerves completes dilation (10 cm) and contractions occur every 2-3 min
- placental stage: uterine contracts help eject placenta (afterbirth)