ch 12 Flashcards
Parthogenesis
unfertilized egg develops into a viable organism(honey bees that display haplodiploid)
Spermatogonia
male germ cell that undergoes 2 meiotic divisions to become spermatids and differentiate into sperm
seminiferous tubules
site of spermatogensis
sertoli cells
activated by FSH, surround and nourish sperm. Produces inhibin which inhibits FSH
spermatogenic cells
produce spermatozoa
epididymis
non-mature sperm travels via peristalsis to here for maturation
Path of ejaculation
seminiferous tubules > Epididymis > Vas Deferens > ejaculatory Duct > urethra > penis
seminal vesicles
secrete fructose (for ATP production in sperm), mucus, cleans and lubricates urethra, and postagladins
prostate gland
alkaline secretions to counteract acidity of uterus
Bulbourerthral glands
viscous mucus
Hormones in males
FSH- sperm development
LH- stims leydig cells to produce testosterone
oviduct
where eggs travel from ovary to uterus
uterus layers
perimetrium, myometrium, endometrium
oogonia
female germ cells, majority die but some differentiate into primary oocytes and are arrested in prophase 1 till puberty
end of meiosis 2 after fertilization
1-2 polar bodies and 1 oocyte are formed
hormones in females
FSH- follicles in ovary development + production of estrogen and progesterone
LH- stimulates ovulation , corpus luteum formation
Menstrual cycle
1) follicular phase- hypothalamus releases GnRH, anterior pituitary releases FSH and LH, FSH binds to ovaries and causes follicles to develop, releases estrogen, endometrium thickens, LH spike, ovulation
2) Ovulation- egg released from Graafian follicle, and egg travels down oviduct awaiting sperm
3) Luteal phase- follicle develops into corpus luteum which produces progesterone and estrogen, and uterine lining thickens
4) if no implantation- LH and FSH drop, corpus luteum no longer maintained, progesterone and estrogen levels drop, endometrium sloughs off
5) if implantation- outer layer of placenta produces HCG which maintains corpus luteum, progesterone and estrogen levels maintained
corona radiata
outmost layer of egg which nourishes egg
Vitelline layer
made of glycoproteins layer in eggs in non-mammals
zona pellucida
layer under corona radiata in mammals made of glycoproteins
Capa Citation
final maturation step for sperm prior to fertilization, destabilizes sperm plasma membrane and results in prep of sperm tip at acrosome, and increased calcium permeability making it hyperactive
Acrosomal reaction
recognition between sperm and egg before fusion, ensures same species, sperm binds to ZP3 protein on zona pellucida, and sperm head releases enzymes to digest zona pellucida and allow sperm to fuse with egg
polyspermy block
prevents polyploidy by preventing polyspermy
1) fast block- Na+ flow into egg and depolarize it preventing sperm binding
2) slow block- gradual, long lasting, Ca+ released into egg to stimulate cortical reaction which makes zona pellucida impenetrable
monozygotic twins
identical, one zygote splits and makes two embryos with identical genetic material
dizygotic twins
fraternal twins, two separate eggs fertilized by 2 separate sperms.
radial cleavage
aligned in vertical axis (deutersomes)
serial cleavage
misaligned cells, deviate from axis (protostomes)
holoblastic cleavage
evenly divides embryo in animals with little yolk (humans, sea urchins) exception: frogs
meroblastic cleavage
partial cleavage, not evenly divided, in animals with a lot of yolk, exhibits polarity with animals pole and vegetal pole
morula
ball of blastomeres at 12-16 cells
blastula stage
128 cells stage
bastocoel
hollow, fluid filled center
Blastula form:
1) trophoblast- forms embryonic membrane, implants embryos in uterus, produced HCG
2)inner cell mass- forms embryo, differentiates into
epiblast- contriubutes to main embryo and cells thicken to form primitive streak
hypoblast- partially contributes to yolk sac
gastrulation
formation of trilaminar embryo, epiblast cells invaginate inwards through primitive streak to form 3 layers: endoderm, mesoderm, ectoderm
ectoderm forms
CNS, PNS, sensory parts of ear eye nose, epidermis layer of skin, hair, nails, mammary and sweat glads, pigmentation cells, enamel, adrenal medulla
mesoderm forms
bone and skeleton, muscle, cardiovascular, gonads, adrenal cortex, spleen, notochord
ectoderm forms
epithelial lining of digestive, respiratory, exceretory, pancreas, liver, thyroid, parathyroid, thymus
neurulation
nervous system development
notochord
stimulates ectoderm to thicken forming neural plate
neural plate
fold onto itself causing neural fold, which will continue ro fold onto itself forming neural tube
neural tube
differentiates into CNS, mesoderm cells form two masses alongside notochord and become vertebrate and skeletal muscles
Amnion
innermost layer, membrane around embryo secretes embryonic fluid
chorion
outermost layer, in mammals it forms placenta and in egg-laying it is a membrane for gas exchange
allantois
sac that buds off the archenteron. Stores waste for disposal.
Mammals- become umbilical cord
egg laying- initially stores uric acid then fuses with chorion
yolk sac
mammals- transient function until placenta develops, first site of blood cell formation
egg laying- sole provider of nutrients
embryonic induction
organizers secrete chemicals that influence what neighboring cells become in the future
homeotic genes
master controller, turns genes on and off
egg cytoplasmic determinant
if egg cytoplasm is unevenly distributed, an axis is created influencing how the embryo divides during cleavage
