Fertilization-5 weeks Flashcards
function of meiosis
halves chromosomes - 23 pair to singles
of chomosomes, autosomes, sex chromosomes in somatic cell
46 chromosomes, 23 pairs, 22 pairs of autosomes, 2 sex
of chomosomes, autosomes, sex chromosomes in gamete
23 chromosomes, 23 singles, 22 single of autosomes, 1 sex
proportion of newborns with abnormal chromosome #
1:160
define non-disjunction
failure of proper separation leading to aneuploidy
end cells of non-disjunction in Mei 1
2 with 24 (leads to trisomy) and 2 with 22 (leads to monosomy)
end cells of non-disjunciton in Mei 2
2 normal, 1 with 24, 1 with 22
actions in 2 phases of spermatogenisis
- spermatogonia>Mei 1 and 2>spermatids
2. spermatids>spermiogenesis>spermatozoa
sperm cell production per day
50-150 million
production points and amounts of seminal fluid
seminal vesicles (60%), prostate (30), bulbourethrea glands (10)
names for lack of sperm and abnormal sperm
lack -azoospermia
weird - oliogspermia
normal site of fert.
ampulla of uterine tube
life span of sperm
2-6 days
life span of oocyte
24 hours
function of sperm capacitation
- egg attach
2. acrosome reaction
stages of oogenisis and timeline
primary oocyte>9/10 of mei 1 (fetal, ends at ovulation)>secondary oocyte>mei 2 (just before ovulaiton, only complete if fert.)>ovum
contents of primordial follicle
primary oocyte arrested in prophase until ovulation
layers of primary follicles and function
primary oocyte
zona pellucida - extracellular matrix
follicular cells - secrete estrogen
theca produce androgens
diff between primary and sec. follicles
larger and have antrum (fluid filled spaces)
time for primary follicle to dev into mature secondary follicle (graffian)
3 months
time of meiosis 2 in oocyte
just before ovulation (out of ovary)
creation of meiosis 1
secondary oocyte and 1st polar body
remnants of ovulation
corpus luteum
stages of fertiliazation
sperm-zone binding>acrosome reaction>sperm egg binding
define zona binding
sites on sperm cell membrane bind with zona pellucida
define acrosome reaction
outer part of acrosome fuses and release enzymes to penetrate zona pellucida
define sperm egg binding
ligand on sperm membrane binds with receptor on secondary oocyte
block to polyspermia
sperm cell membrane contact>cortical granules>zona reaction
point of mei 2
immed. following fertilization
time until first cleavage
24 hrs then 12>24>12 etc
name of cells created by cleavage
blastomeres
name of collection of blastomeres
morula
stage at which compaction occurs
8 cell - bw 3 and 4 divs
name of inner and outer cells formed in cell compaction
outer- trophoblast
inner - inner cell mass
name of fluid filled cavity in morula
blastocyst
time until implantation
5-6 days
products of trophoblast joining the endometrium
syncytiotrophoblast - invades endometrium
cytotrophoblast - what is left
what prevents early implantation
zona pellucida
frequency of ectopic preg
1/100
most common location of ectopic
tubal
product of implantation from inner cell mass
bilaminar disc
hypoblast - towards blastocyst - no direct contribution
epiblast - develops amniotic cavity
two balloons which bilaminar disc is sandwiched between
yolk sac and amniotic cavity
period of gastrulation
3rd week
direction of proliferation epiblast cells
medial and caudal
name of cranial end of primitive streak
hensen’s node
layer formed between epiblast and endoderm
mesoderm
layer formed by remaining epiblast cells
ectoderm
layer formed by ingressing cells of epiblast
endoderm
end of tissues that are more progressive
rostral end
organizer of embryonic development
notochord
tissues created by ectoderm
nervous system, tissues of body surface, glands that connect to body surface
3 stages of neurulation
- induction of neural plate - initiated by notochord
- elevation of neural folds - neural crest cells begin to roll up
- fusion of neural folds - contact os made to creat a tube
direction in which neurulation occurs
both rostral and caudal
fate of neural crest cells
various different nervous system structures
tissues created by endoderm
lining of GI, secretory cells of GI, lining of resp system
2 directions of embryonic folding and their products
- long axis - foregut and hindgut
2. short axis - midgut
products of foregut
mouth, eso ,and down to bile duct (Celiac)
products of midgut
small intestine from bile duct to distal transvers colon (SMA)
products of hindgut
distal trans colon to anus, bladder and urethra (IMA)
tissues created by mesoderm
most muscle and connective tissue
3 regions of mesoderm
- paraxial (inner)
- lateral (outer)
- intermediate
embryonic stages of paraaxial mesoderm and porducts
somites - vert, ribs, skeletal muscles of body wall
division and products of lateral mesoderm (3)
- somatic mesoderm - connective tissues, blood vessels of body wall and limbs
- splanchnic mesoderm - smooth muscle, blood vessels of GI
- intraembyronic coelom - main body cavities (pleura etc.)
products of intermediate mesoderm
uriniary system and gonads
what happens before Mei 1
DNA replication
What happens at Mei 1
chromosomes separate
what happens at mei 2
chromatids separate
