Embryology Flashcards
Gametogenesis
formation of gametes
Spermatogenesis
formation of sperm
how long does spermatogenesis take
64 days
Oogenesis
formation of female gamete
How long does oogenesis take?
it begins at same time as male gametes, halts at prophase and continues at puberty
Nondisjunction
failure of sister chromatids to separate during cell division
what can nondisjunction in meiosis lead to?
trisomy 21
Fertilization
fusion of sperm and oocyte to form a zygote
zygote
diploid single cell that will develop into an embryo
cleavage
mitotic cell division of zygote to form a morula
gastrulation
formation of three primary germ layers (ectoderm, mesoderm and endoderm) and the body axis are established
where does fertilisation occur
ampulla
describe fertilisation
sperm binds to zona pellucide, an acrosomal reaction occurs (acrosomal enzymes released by head of sperm), sperm and oocyte membrane fuse, oocyte completes meiosis 2 and releases cortical granules
how is a blastocyst formed
morula undergoes compaction, blastomere is no longer identifiable, fluid enters through the zone pellucid and forms blastocyst cavity, the outer layer of the cells become known as trophoblast layers, cells group together to form an inner cell mass, the blastocyst breaks free from the now restrictive zone pellucid in order to begin implantation in uterine lining
what day does implantation occur
day 6
