Embryonic Period Flashcards
Process completed once sperm cell enters secondary oocyte
Meiosis II
Mature egg
Ovum
Pronuclei (plural for pronucleus)
Nucleus of the sperm or the ovum during fertilization, before genetic materials fuse
Process to be completed once sperm enters secondary oocyte
Meiosis II
Diploid
Two haploids
Zygote (cell type)
Diploid (two haploids that merge together)
Zygote
1st embryonic stage
Fertilization takes place in part of the body
Uterine tubes
Zygote lives in uterine tube for how many days
4-5 days
Cleavage
Division of zygote (by mitosis)
Cells produced by cleavage
Blastomeres
Cleavage of zygote (day, stage)
Day 1 after fertilization; two-cell stage
Cleavage of zygote (day, stage)
Day 2 after fertilization; four-cell stage
Morula (day)
Day 3-4 after fertilization
Blastocyst (day)
Day 5 after fertilization
Describe a morula
Solid ball of cells
Describe blastocyst
Hollow ball of cells
Implantation (Day, Location)
Day 5 after fertilization, uterine tubes
Part of endometrium that is modified after implantation
Decidua basalis
Blastocyst inner cell mass
Embryoblast
Blastocyst (outer layer)
Trophoblast
Implantation of blastocyst (day, location)
Day 7-8 after fertilization, endometrium (uterus)
Fertilization occurs
12-24 hours after ovulation
Part of blastocyst that attaches to endometrium (uterus) during implementation
Embryoblast (inner cell mass)
Blastocyst changes during implementation (Day 8)
Trophoblast > Cytotrophoblast and Syncytiotrophoblast
Embryoblast > Epiblast and Amnion forming (amniotic cavity)
Bilaminar embryonic disc (consists of what layers)
Hypoblast
Epiblast
Inner membrane formed in the blastocyst cavity at implementation
Exocoelomic membrane
Maternal sinusoids chorion (consists of what three parts)
1) extraembryonic mesoderm
2) syncytiotrophoblast
3) cytotrophoblast
Exocoelomic membrane surrounds
Yolk sac
Yolk sac formed
Day 9
Extraembryonic mesoderm (part of)
Maternal sinusoids chorion
Extraembryonic mesoderm forms (day)
Day 12 after fertilization
4 extraembryonic membranes
Yolk sac
Amnion
Allantosis
Chorion
Trilaminar embryonic disc cells become
Fetus
Innermost membrane (4 extraembryonic membranes)
Amnion
Becomes the site of early blood formation (4 extraembryonic membranes)
Yolk sac
Forms fetal portion of placenta (4 extraembryonic membranes)
Chorion
Takes over production of hCG (4 extraembryonic membranes)
Chorion
Helps form the umbilical cord (4 extraembryonic membranes)
Allantosis
Continues to rescue the corpus luteum from degeneration, sustains secretion of progesterone and estrogens
Chorion
Placenta is formed by what part of the embryo and endometrium
Chorionic villi (embryo) Decidua basalis (endometrium)
Trilaminar embryonic discs
Ectoderm (outer)
Mesoderm (middle)
Endoderm (inner)
Process of gastrulation
Formation of three germ layers
Three germ layers
Ectoderm
Mesoderm
Endoderm
Crainocaudal axis (germ layer)
Ectoderm
Medial/lateral & dorsoventral (germ layer)
Mesoderm
Ventral (germ layer)
Endoderm
Primitive node & streak (germ layer)
Ectoderm
Notochord, somites (germ layer)
Mesoderm
Ectoderm (derivatives)
Nervous system, neural crest, epithelium
Mesoderm (derivatives)
Skeletal muscle and connective tissue
Endoderm (derivatives)
Gut, pharyngeal apparatus & allantosis
Ectoderm (derivatives)
Brain, nerves, skin, sweat glands, hair
Mesoderm (derivatives)
Mesenchyme (loosely organized connective tissue) that forms
blood, muscles, bones, and other connective tissue derivatives (kidneys, bladder, ovaries, testes, heart muscle)
Endoderm (derivatives)
Epithelial lining of digestive tract, respiratory tract, and organs (lungs, liver, pancreas, esophagus, stomach, intestines)
Endothelial lining of blood vessels
Meiosis II
Secondary oocyte > ovum and polar body > pronuclei fuse
Mitotic division
Cleavage
Steps in the embryonic period
Embryogenesis Cleavage (day 1) Blastulation (day 3-4) Implementation (day 7-8) Gastrulation
Process of forming three primordial germ layers
Gastrulation
Responsible for maintaining uterine environments and preparing mammary glands for breast feeding
Placenta
Why is the placenta unique
Develops in both mother and fetus
Job of the placenta for the fetus
Nutrient and waste management
Takes over homogeneous secretion
Placenta
Hormones produced by the placenta
hCG, estrogen, progesterone