1-F Early Development Flashcards
Explain the process of gametogenesis- the formation of female and male germ cells as described in these notes
a. Process that forms gametes (ovum and sperm) converting diploid cells into haploid cells by meiosis
At birth all oogonium have become primary oocytes that are stuck in
prophase I
What is the sequence of primordial follicule to ovulation?
primordial follicle, primary follicule, secondary follicle, ovulationof secondary oocyte with zona pellucida and corona radiata
Primordial follicles consist of primary oocyte surrounded
zona pellucida and supported by follicular cells
Maturation of primordial follicles mature through primary and secondary follicles and what forms in the follicular cell layer
antrum
What is ovulated
a secondary oocyte including a zona pellucida and corona radiata
After the ovum is released into the peritoneal most enter ____
the fimbriated end of the oviduct
Ovulation causes the oocyte to re-enter what part of the cycle
meiosis and once again halting at metaphase II
Locate where fertilization occurs
normally occurs at the ovarian end of the uterine tube, occurs once the sperm enters the secondary oocyte to form the zygote
After fertilization all mitotic divisions are called:
cleavages
Define early development
the process of zygote transforming into an embryonic disc (multicellular, tralaminar disc, period lasting 3 weeks
Define differential growth
some areas grow more than others
Define cavitaiton
hollowing out of a ball of cells
Define cell migration
movement of cells from one place to another
Define cell death
programed destruction of tissue due to development
Define bud formation
bulging of cells open at one end
Define tube formation
a cylinder of cells open at two ends
Zygote
fusion of primary oocyte and sperm forming a diploid cell
zona pellucida
glycoprotein layer which protects and nourishes the oocyte, found around the oocyte in the primordial follicule, primary and secondary follicle and zygote pre-implantation
morula
16- cells stage of embryo made of a solid ball of blastomeres (undiferentiated and plueripotent)
blastula
embryo after the morula cavitates, creating a hollow cavity called the bastocoel
trophoblastic cells
of the blastula, the cells that form the outer surface of the cavity, they eventually become the placenta and extraembryonic membranes
inner cell mass/ embryoblasts
one pole of the blastula has a concentration of cells that will develop into an embryo
implantation
trophoblasts of the blastula attach to and burry into the uterine lining
Why are ectopic pregnancies dangerous to the mother?
pregnancies that implant outside the uterus and are at great risk for vascular risk
endometrium
uterine lining
Embryo v. Fetus
embryo before 8 weeks, fetus after 8 weeks
What happens during blastocyst “hatching”
blastocyst exits the zona pellucida as it degenerates and is ready for implantation
Once blastula forms what is the first big step towards creating a bilaminar disc/
implantation occurs simulateously with diffentiation of trophoblasts and embryoblasts
What are the two distinct layers of the inner cell mass that differentiate then cavitate
epiblast and hypoblast
The cavities that are formed by the epiblas and the hypoblast will be joined an that region will develop into
the bilaminar disk
Name the cavity formed once the epiblast cavitates
primitive amniotic cavity
Name the cavity formed when the hypoblast cavitates
primitive yolk sac cavity
During implantation, trophoblast cells differentiate into which two types of cells?
syncytiotrphoblasts and cytotrophblasts
What is the role of cytotrophoblasts?
unfused cells surrounding the inner mass of cells, form a circle around the developing embryoblast
What is the function of syntiotrophoblast cells?
fuse and burrow into to the endometrium, become supporting cells for the developing embryo, part of the developing placenta
Which cells form the extraembryonic mesoderm?
cytrophoblasts
Adding the extraembryonic mesoderm converts the primative extraembryonic tissues into:
amnion, chorion, extraembryonic coelom, connecting stalk
amnion
primitive amnion plus extrembryonic mesoderm
chorion
trophoblasts plus the extraembryonic mesoderm
extraembryonic coelom
space separating the the chorion from the embryo, amnion and yolk sac, fetus grows into this space
connecting stalk
attaches the chorion to the amniotic and yolk sac cavities and becomes the umbilical cord
What is the function of the structures that will be produced by the extraembryonic mesoderm
future structures will support the developing embryo and fetus, forming no embryonic structures
Describe major events associated with gastrulation
transformation of bilaminar disc to a trilaminar disc, formation of primative streak and migration of cells
All 3 germ cell layers of formed from what type of embryoblast cells?
epiblast
Name the three germ cell layers
ectoderm, mesoderm and endoderm
Describe the migration that creaste mesoderm
cells that migrate through the primative streak and continue laterally
Describe the migration of cells that create the endoderm
cells that migrate below the forming mesoderm to replace hypoblast cells
How is the notochord formed?
migration of cells through the primative streak and directly cranially (mesoderm)
Which spots on the trilaminar disc do not contain mesoderm
the oral and cloacal plates
What directional details are established in gastrulation
body axes
What do we call epiblast cells that do not migrate
ectoderm
How is loose mesoderm formed
by epiblast cells that migrate through the primitive streak and migrate laterally
What does the embryo look like at the end of gastrulation
trilaminar disc
Name tissues formed by ectoderm
skin, nervous tissue
Name tissues formed by the mesoderm.
muscle, bone, connective tissue, circulatory system
Name tisses formed by the endoderm
epithelial linings of the gut tube, respiratory tract and the urinary tract
What are the major features of development associated with the embryo
organstystems are formed, derived from the primitive germ layers
