Exam I Flashcards
Period of embryo
3-8weeks
Period of egg
2 weeks
Period of fetus
9-40weeks
Gametogenesis
Joining sperm and egg
Cleavage
Subdividing fertilized egg; no growth in overall size
Gastrulation
Flat disk of cells, axes form, endo- ecto- and mesoderm
Morphogenesis
Folds into tubular embryo
Organogenesis
Organ systems form
primordial germ cells
Form separate from gonads
isolate in yolk sac to reduce signals from somatic cells
migrate after reducing signals
autonomous specification
mature unfertilized egg has determinant molecules in cytoplasm; this region destined to become PGCs; seen in amphibians
embryonic induction
signaling between cells induces PGCs
animal pole
region of egg with nucleus
vegetal pole
region of egg without nucleus where yolk forms
contains determinant molecules (in autonomous organisms)
damage to area leads to no PGCs
day 0
pronuclear stage
day 5
blastocyst
inner cell mass and trophoblast surrounded by zona pellucida
embryo must hatch before implanting
Txn represssor factors expressed in PGCs
Blimp1
Prdm14
both proteins expressed=PGC
Blimp1
suppress genes associated with somatic cell formation and activate pluripotency genes
pluripotency genes
nanog
sox2
oct4
Prdm14
activate pluripotency
PGC migration
filopodia fibronectin (intercellular protein) binds integrin receptors on surface (somehow important) saf1 secreted by gonads=chemotaxis?
stem cell factor (SCF)
secreted by cells surrounding PGCs during migration
PGCs by number
detected in epiblast of mice: 6
end of migration: 4000
teratomas
when PGCs end up in wrong location
- mediastinum (chest)
- oral
- sacrococcygeal
inert gene hypothesis
PGCs demonstrate large scale gene repression (expression of somatic genes)
isolate and repress idea
testis structure
divided into cavities of seminiferous tubules
Pre-puberty: PGCs and sertoli cells
at puberty: PGCs begin spermatogenesis
BMP8b
produced by PGCs at puberty
higher levels leads to differentiation of PGC into spermatogonia between sertoli cells
sertoli cell function
structure
secretion
structural function of sertoli cells
basal and adluminal compartments- separate at junctions of sertoli cells
blood-testis barrier- prevents immuno attack of sperm due to expression of antigens not present in somatic cells
secretory function of sertoli cells
mullerian inhibiting substance- causes mullerian duct degredation in males
androgen binding protein- increses spermatogenesis
inhibitin- negative feedback to anterior pituitary
Hormone regulation of spermatogenesis
bypothalamus secretes GnRH
anerior pituitary releases FSH
Sertoli cells secrete androgen binding protein
increases testosterone levels
increases spermatogenesis
inhibitin=negative feedback to pituitary from sertoli cells
PGC=>Sperm
BMP8b high: PGC -> spermatogonia
at puberty: spermatogonia type A -> B
type B -meiosis-> 1* spermatocyte ->2* spermatocyte -> spermatid -> spermatozoa
GDNF
from sertoli cells
high B into more B
low B into 1*
Stem Cell Factor SCF
from sertoli
promote B -> 1*
timeframe of spermatogenesis
A-B: 16 days
1*-spermatids: 24 days
spermatid-spermatozoa: 24 days
spermiogenesis
golgi phase
cap phase
acrosome phase
maturation phase
golgi phase
acrosomal granule from golgi forms vesicle at nucleus
proximal centriole used in egg cell division
distal centriole aides tail formation
manchette- temporary protein fibers that sort into tail
cap phase
acrosome forms cap by close association with nucleus
acrosome phase
acrosome completes development
vesicle drapes over nucleus head
tail completes development with mitochondrial sheath
maturation phase
nucleus compacts- protamines instead of histones
cytoplasm sloughed
tubulobulbar complex
sperm structure
acrosomal cap
nucleus
connecting piece with proximal centriole
Tail
Sperm tail
Middle- axonene surrounded by protein fibers; mitochondrial sheath gives energy for motion
Principal- fiber around axonene
End- axonene
Oligospermia
Low count
Teratospermia
Abnormal sperm %
Male vs female gametogenesis
Male pause at PGC until puberty
Female pause at p1 of 1* oocyte until puberty
1* oocyte count
5mos fetus- 7 million
Birth- 700,000
Puberty- 400,000
Menopause- 0?
Menstrual cycle
Ovarian
Uterine
Cervical
Ovarian cycle
Oocyte and follicle maturation
Uterine cycle
Buildup and sloughing of uterine lining
Cervical cycle
Thinning of cervical mucous at ovulation
Menstrual phase
Days 0-5
Uterine lining shed
Some oocytes grow
Proliferative phase
Days 5-14
Hypothalamus releases GnRH, pituitary releases FSH and LH, estrogen incease, thickens uterine lining, G to E mucous, follicle matures
primary egg envelope
zona pellucida (glycoprotein)
cumulus cells
vitilline envelope in amphibians
factors produced by oocyte and follicle cells
oocyte: GDF9
follicle cells: FGF2
yolk
platelets
vitellogenin from liver taken up by oocyte
alecithal
no yolk
humans
micrrolecithal
small yolk
invrtebrates
megalecithal
huge yolk
cell division confined to cytoplasmic disk
mesolecithal
moderate yolk
amphibians
centolecithal
nuclei divide and move to periphery
acotex
outer cytoplasm
more solidified
corticle granule
membrane bound contents near cell membrane, released during fertilization
protective chemicals
produced in external fertilizers; UV protection; bad taste
ovulatory surge
LH and FSH
moves oocyte from M1 to M2 and leads to ovulation
hyaluronic acid
increased production by cumulus cells ffor uptake
granulosa cells
bind progesterone
activates protease production, increased fluid, and prostaglandins for smooth muscle contraction
secretory phase
days 14-28
follicle ruptures
fimbria drape over ovary
villi cause fluid movement which sweeps up egg
corpus luteum
ruptured follicle
produces progesterone which increases uterine lining and inhibits FSH
corpus albicans
degenerate follicle if no fertilization
isthmus
junction of uterus and oviduct
sperm counts
20-200 million/ ml
100-200 make it into oviduct
sperm mobility
nonmobile
non-progressively motile
non-linear motility
progressively motile
semen contributions
seminal vesicles: 60%: alkaline, fructose, protease, prostaglandins
Prostate: 30%: citrates; acidic, seminal plasmin
bulbourethral: 5%: alkaline, mucous
seminiferous tubules: 5%: fluid
pH
vaginal 3.8-4.5
semen: .2
cervix: 6-6.5
sea urchin fertilization
sperm to jelly which produces SAP (resact)
acrosome reaction
digestion of jelly
bind VE
fuse of acrosomal process with egg membrane
acrosome reaction
acrosome and nuclear membranes fuse and release vesicle contents
actin assembles to produce microfilaments for process
acrosomal tubule
bindin on surface binds protein on VE
fertilization cone rises and engulfs
sperm movement
hyperactivation
themotaxis
chemotaxis (progesterone from mature follicle)
capacitation
capacitation
sperm must bind in isthmus
albumin removes cholesterol from membrane
removes some proteins and cabs to unmask binding site
change in potential
protein phosphorylation
acrosomal rxn of mammalian sperm
after capacitation as movin through cumulus cells
bind and then dissolve ZP
zona pellucida
glycoprotein: ZP1, 2, 3 and accessory proteins
binding of egg and spem
CD9 of egg
IZUMO of sperm
fast block
change in membrane potential
temporary
external fertilizers
-70to +20 with Na2+ influx
slow block
mechanical
all
release of cortical granules
