MIDTERM QUESTIONS Flashcards
is the biological sex of an embryo already determined
yes because it will always contain an XX or XY
when do the forming sperm cells go from 2n (XY) to n (X or Y)
the secondary spermatocyte is the first cell that isn’t 2n in the spermatogenesis
what are diploid and haploid cells
diploid = 2n
haploid = 1n
are somatic and germ cells diploid or haploid cells
diploid
what are totipotent cells
cells capable to differentiate into any type of embryonic (body) or extra-embryonic (placenta) cells
what are trophectoderm cells
multipotent cells capable to differentiate into ant type of cell within a cell lineage in this case placenta cells
what are pluripotent cells
cells capable to differentiate into any type of cell in the embryo
where can you find pluripotent cells
in the inner cell mass of blastocytes
what are the levels of early embryogenesis
- highly specialized cells - oocyte and sperm which then get fertilized
- totipotent cells which forms the zygote
- The blastocyst contains the inner cell mass (pluripotent) and the trophectoderm (extraembryonic, NOT part of the embryo).
what causes cells to become a liver or an intestine if they all contain the same DNA
their epigenitics and the differentiation of markers. modifications of DNA or transcription of different areas of the DNA leads to the cell becoming something more specialized
what is gastrulation
the formation of the 3 layers - ectoderm, mesoderm, and endoderm
how does gastrulation work
Step 1: Inner cell mass contains epiblast and hypoblast
Step 2: The epiblast cells migrate through the primitive streak and form both mesoderm and endoderm. The hypoblast does not become the endoderm.
Step 3: The epiblast gives rise to ALL three germ layers. The hypoblast does NOT become the endoderm; instead, it forms extraembryonic tissues (yolk sac lining).
where will the epiblast cells differentiate in the inner cell mass
Epiblast cells differentiate in the central region of the inner cell mass, forming the embryo proper and amniotic ectoderm.
Which inner cell mass cells are attached to the blastocoel?
The hypoblast (primitive endoderm) cells are attached to the blastocoel and contribute to the yolk sac.
what does the endoderm form
digestive system, lungs, and endocrine system
what does the mesoderm form
muscle, skeleton, cardiovasculsr stsem, reproductive system, urninary system
what does the ectoderm form
nervous system, hair, skin, external parts of the reproductive tract
what type of cell will develop the reproductive and uniary system
somitic mesoderm
what are the founder cells for the germline in animals as embryos? where are they found?
primordial germ cells
found in the hind gut
how and where do the primordial germ cells migrate during embryogenesis? what signal coordinates this migration?
migrate by amoeboid movement via the dorsal mesentery of the hindgut to the gonadal ridge
chemotaxis signalling
Why do primordial germ cells go to the gonadal ridge
this is where the primitive sex cords are formed
what do the Gonads become in embryogenesis
become the testes or the ovaries
what do the metanephros become
kidneys
What gene does the Y chromosome have that the X doesn’t
the SRY gene (sex determining region on the Y chromosome)
