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What is 1 + 3?
process of forming gametes through meiosis
constitute both sperm and egg cells
occurs in male individuals
results in the formation of 4 functional spermatoza
occurs in female individuals
results in the formation of 1 functional ovum and 3 nonfunctional polar bodies
period of time in which all stages of development occur
union of the sperm and egg
nucleus: formation of a zygote
attachment/penetration of the conceptus into the uterus
a fertilized ovum
sperm vehicle does not enter egg only fuse at shell membrane transferring 23 chromosomes
stage that implants into uterus
developmental stages occurring after the zygote through two weeks
3 required events for conceptus
live 12 to 48 hours
developmental stages occurring from the 3rd week through the 8th week
stage where organogenesis occurs
formation of specific organs in the developing embryo (one chance to form) critical stage for any type of birth defect
developmental stages occurring from the 9th week through birth.
stage of growth
for 29 weeks
or 11 weeks at gestation
twins that develop from a single ovum fertilized by a single spermatozoa
always the same sex!
twins that develop from two different ova that are fertilized by two different spermatozoa
can be same sex or opposite sex!
2 egg division
2 single zygote
2 different humans
1 egg division
2 primary sources of stem cells
adult and embryonic
they are undifferentiated cells
they can potentially be turned into any human tissue
monozygotic split started but did not finish.
nueraltube elongation splits
104 weeks (2 yrs)
gestation is 40 weeks
4 types of stem cells
totus - entire
can create entire organisms
1st 3 divisions of conceptus
pluri - several/any
create parts of an organism
multi - many/limited to subtypes
make any type of blood cells and blood cells only
uni - one
can only make one type of cell
cells in testes