Lab Exam 2: Embryology Flashcards
zygote
fertilized egg
fertilization
egg and sperm nuclei fuse to form single nucleus
blastomeres
zygote begins to divide
forms mass of successively smaller and smaller cells
cleavage
series of mitotic divisions without intervening growth periods
results in multicellular embryonic body
morula
solid ball of cells
at the 32-cell stage
embryo resembles a berry shape
blastula
the cell mass hollows out
ball of cells surrounding a central cavity
this is the final product of cleavage
early gastrula form
one end of blastula has been indented or pushed into the central cavity forming a 2 layered embryo
gastrulation
3 layered embryo forms
each layer corresponds to a primary germ layer that all body tissues develop from
endoderm
innermost layer of primary germ layer
- epithelial lining of respiratory, GI, reproductive tracts, liver, gallbladder
mesoderm
middle layer of primary germ layer
- dermis, skeleton, cardiac, smooth muscle, blood vessels, serous membranes
ectoderm
outer layer of primary germ layer
forms surface tissues of the body
- skin, nervous system, senses, nasal and anal cavities
blastocyst
fluid filled sphere outlined by trophoblast
final product of cleavage
trophoblast
single layer of flattened cells enclosing the embryoblast
embryoblast
inner cell mass
chorion
this is what a trophoblast forms , it is an extraembryonic membrane
forms the fetal portion of the placenta
embryonic disc
forms the embryo proper
has 2 layers
How long is implantation?
about 5 days, it is completed by 12 days after fertilization
portion of embryoblast that eventually lies beneath the embryo
decidua basalis
portion of endometrium on the luminal face of the uterus
decidua capsularis
by the time implantation has completed, embryonic development has progressed to what stage?
gastrula stage
when is the embryo considered a fetus?
by week 9 of development
composite of decidua basalis and chorionic villi
placenta
three extraembryonic membranes
amnion, yolk sac, and allantois
encases the young embryonic body in a fluid-filled chamber that protects embryo against mechanical trauma and temperature extremes , prevents adhesions during rapid embryonic growth
amnion
in humans: yolk sac lost original function which was to
pass nutrients to embryo after digesting the yolk mass , now the role of?
placenta
where embryos first blood cells originate and primordial germ cells migrate from it into embryo’s body to seed gonadal tissue
- forms part of digestive tube
yolk sac
protrudes from posterior end of yolk sac
- redundant in humans bc of placenta
- birds and reptiles: embryonic wastes
- humans: structural basis on which the mesoderm migrates to form umbilical cord
allantois
attaches embryo to placenta
umbilical cord
4 cell stage
2 days
oocyte
egg
early blastocyst
morula hollows out and fills with fluid, 4 days
zona pellucida
area around the blastocyst
ceolom
hollow, fluid-filled cavity that will provide cushion for internal organs
uterus
organ where offspring are conceived
uterine cavity
inside of uterus, triangular shape
fertilization membrane
membranous layer that forms post fertilization by thickening membrane, on microscope it looks like halo around cell
amniotic cavity vs amnion
amniotic cavity : closed sac between amnion and embryo containing amniotic fluid
amnion: is the membrane forming the fluid-filled cavity
endometrium
mucous membrane lining the uterus, thickens during menstrual cycle
blastocyst cavity
cavity in the morula that is filled with fluid
ovulation
process when mature egg is released from an ovary
- it is halfway through a menstrual cycle, about 6 days
- best time to get pregnant
fallopian tube
where conception occurs
ovary
female glands where estrogen and progesterone are made
eggs are also made in the ovaries
