Chapter 8 Flashcards
Which gamete can contribute either and X or a Y
sperm
T/F Y chromosomes have a fraction of the genes compared to X chromosomes
True
SRY gene
a gene present of the Y chromosome which determines the sex of a human
What happens if the SRY gene is deleted?
XY fetuses develop female reproductive systems
What system develops and which degenerates in fetuses with SRY genes?
Wolffian system develops and Mullerian system degenerates
what is are the primordial reproductive systems?
Wolffian - male
Mullerian - female
T/F mammals have genotypic sex determination
True
What is the timeline for the zygote stage
0-2 weeks
what is the timeline of the embryonic stage
2-8 weeks
T/F there are large differences between vertebrates in the embryonic stage
F - they look alike as embryos and develop more distinct forms as they grow
What are the organizer tissue layers and what do they develop into?
Ectoderm - skin
Mesoderm - muscles and bone
Endoderm - digestive and respiratory
what is the first stage of nervous system development
neural plate stage in embryo
what is the second stage of nervous system development
neural tube stage, where the plate folds and forms a tube
what protects the nervous system during development
skin and bone encasement
what does the hollowed area of the neural tube become
the ventricles
Where does the peripheral nervous system develop from
neural crest
What are of the nervous system serves as a nursery for the rest of the developing CNS
neural tube
spina bifida
failure of the neural tube to close completely leaving a portion of the spinal cord uncovered
how is spina bifida fixed?
through surgery, though may result in paralysis
anencephaly
front end of the neural tube does not close leading to lack of forebrain development
how is anencephaly fixed
it is not fixable, will be fatal
when does fetal heart beat begin
35 days
where does stem cell proliferation occur
sub ventricular zone
what does it mean to say that stem cells are totipotent
they have the ability to become any kind of cell