Embryo and Genetics

what is gametogenesis

production of gametes (eggs/sperm) from primordial germ cells

how do gametes differ from somatic cells

haploid

what does gametogenesis consist of

meiosis and cytodifferentiation

what is cytodifferentiation

the structural and functional changes (maturation phase) required for sperm and egg to unite

what are somatic cells

everything in body besides gametes

what happens during interphase

chromosomes duplicate in prep for mitosis or meiosis

what does meiosis 1 produce

2 daughter cells with 23 duplicated chromosomes each

what does meiosis 1 produce

2 daughter cells with 23 single chromatids each

what is aneuploidy. most common types?

abnormal # of chromosomes. usually trisomy or monosomy

what is nondisjunction

failure of chromosomes to separate in meiosis. creates daughter cells with weird chromosome #s

what does most aneuploidy result in

spontaneous abortion (picture explosion)

which gamete is more likely to suffer non disjunction

ova. 20-60% affected vs 2-3% of sperm

where is location of spermatogenesis

seminiferous tubules

why are testes outside body

temp. keeps em 2 degrees colder for sperm production

how do spermatogenesis and oogenesis differ timing wise

spermatogenesis begins at puberty and lasts for life. oogenesis begins at birth. arrested till puberty then lasts till menopause

function of Sertoli cells

nourish growing sperm and form testis blood barrier that keeps immune cells out

what are leydig cells and where are they found

cells that produce testosterone. found between seminiferous tubules

order of sperm development

spermatogonia to primary spermatocyte to primary spermatocyte to spermatid to spermatozoa

time needed for spermatogenesis

64-74 days

what are the types of spermatogonia

type A and type B

type A spermatogonia

diploid stem cells that regenerate. as long as these exist youll always make sperm

type B spermatogonia

spermatogonia that becomes sperm. type a that has differentiated

what happens in phase 1 of spermatogenesis

type B spermatogonia does mitosis to become primary spermatocytes. primary spermatocytes do meiosis 1 to become secondary spermatocytes. secondary spermatocytes do meiosis 2 to become spermatids

what is the ploidy of primary spermatocytes

2n

what is the ploidy of secondary spermatocytes

1n

what is phase 2 of spermatogenesis called

spermiogenesis

what happens in spermiogenesis

golgi creates acrosomal enzymes and acrosomal cap forms. tail created.cytoplasm shed

what kind of enzymes are found in the acrosome

hydrolytic

what is spermiation

release of mature speratids from sertoli cells into lumen of seminiferous tubule

where does sperm mature

epididymis

what is the passive transport in sperm transportation

sperm that have completed differentiation released out of tubules by testicular fluid in efferent ducts

what is the active transport in sperm transportation

sperm travel via vas deferens to seminal vesicles until needed

sperm transit in male tract

passive transfer to epidiymis by testicular fluid, mature in epididymis, active transport by vas deferent. seminal fluid added, prostatic fluid added, pre cum added, nut

when does seminal fluid get added

when ur nutting

seminal fluid fn

feed sperm, neutralize vag acidity, promote motility

what do the vaginal villi do with respect to sperm

move the egg but keep sperm out

sperm transit in female tract

sperm goes from upper vag to cervix, uterus, uterine tubes, to egg

what is sperm capacitation

hyperactivity of flagella that occurs in female body. removes cholesterol coat, tails moves fast, increased metabolism

why is capacitation important for sperm

only capacitated sperm can do the acrosome reaction and fertilize egg

what are the 2 parts of oogenesis

oocyte development and follicle development (folliculogenesis)

what is mature follicle called

graffian follicle

what happens to the primary oocyte

gets arrested in prophase 1 before birth. arrested till puberty

how many oocytes left at puberty

400k ish from 1-2 mil start

ploidy of primary oocyte

2n

ploidy of secondary oocyte

n

what happens to primary oocyte after puberty

unattested and undergoes meiosis 1 to become secondary oocyte. secondary oocyte arrested in metaphase 2 and ovulated

when does secondary oocyte complete meiosis 2

only if egg fertilized. otherwise dies

what are the byproducts of each egg meiosis

polar body

how many polar bodies are made in oogenesis (assume fertilized)

3

why do polar bodies die

not enough cytoplasm

what does the empty follicle become after ovulation

corpus lutem

function of corpus lutem

produce progesterone, estrogen and inhibin A

follicle stages

primordial follicle, primary, secondary, mature, corpus lutem

what does the corpus lutem become if no pregnancy

corpus albicans

does corpus lutem produce hog

no its SUSTAINED by hcg from embryo

fn of progesterone

maintains uterine lining for implantation

what layer of cells covers the egg in the secondary follicle

cumulus oophorus

cell type of primordial follicle

flat epithelial

what happens to primordial follicle cells as it becomes primary

flat epithelial becomes cuboidal epithelial

fn of zona pellucida

prevents sperm entry. broken during fertilization

function of fimbrae

picks up ovulated complex and directs to uterine tube

where specifically does fertilization happen

ampulla of uterine tube

how long does corpus lutem stick around

2 weeks if no pregnancuy. till placenta forms if pregnant

what happens during phase 1 of fertilization

sperm sneak through corona radiata using power of uterine tube and sperm enzymes and the power of friendship

what happens during phase 2 of fertilization

sperm binds to zp3 receptor on zona pellucida and begins acrosome reaction

what is the acrosome reaction

release of acrosin from acrosomal cap to penetrate zp

what is the cortical reaction

release of cortical granules (lysosomes) from egg cytoplasm. enzymes from granules cause a shedding of juno receptors from oolema and change zp permeability to prevent polyspermy

what happens in phase 3 of fertilization

sperm and egg membranes fuse. izumo1 molecule on sperm binds to juno receptor on egg membrane to allow fusion

does the whole sperm enter the egg

no. just the nucleus

what is a pronucleus and when is it found

nucleus of mature egg or sperm. found just after fertilization but before zygote formation. 24 hr period

what cells does zygote cleavage produce

blastomeres

what are blastomeres

totipotent cells surrounded by ZP

totipotent meaning

every cell has the potential to turn into a baby/ can develop into intra or extra embryonic structures

what is compaction

blastomeres compact to form morula. cells flatten to form tight ball. inner cells become embryo. outer cells become trophoblast. happens after 8 cell stage

what is a morula

12-32 cell stage

what is the trophoblast

outer cell mass cells that form extra embryonic tissues like placenta

what is the embryoblast

inner cell mass cells that form intra embryonic tissues

what is the blastocoel and when does it develop

cavity of blastocyst. day 4

when does morula enter uterine cavity

day 3

on what part of blastocyst does implantation happen

at embryonic pole. hatches out of ZP

how does blastocyst hatch from ZP to implant

trophoblast’s proteolytic enzymes degenerate ZP. happens days 4-6

what happens at day 7

implantation. officially preggers

what to remember about week 2 of baby making

rule of 2. everything doubles and names change

what does trophoblast differentiate into

cytotrophoblast and syncytiotrophoblast

what does embryoblast differentiate into

epiblast and hypoblast

what does the blastocoel become

amnitiotic cavity and primary yolk sac cavity

what does extraembryonic mesoderm become in week 2

somatic and splanchnic mesoderm

what does cytotrophoblast eventually become

placenta

what does syncytiotrophoblast eventually become

villi that invades uterus

what does epiblast form +location

embryo. dorsal (back)

what does hypoblast form +location

extra embryonic shit. ventral (front)

where does blastocyst implant

endometrium of posterior superior wall of uterus

when does implantation occur

secretory phase of menstrual cycle

WHAT IS MAIN SUPER IMPORTANT FN OF SYNCYTIOTROPHOBLAST

make b-hcg to maintain corpus lutem

what options do new cytotrophoblast cells have after mitosis

stay in cytotrophoblast or migrate and become syncytiotrophoblast

why are babies a parasite

cause syncytiotrophoblast burrows into maternal tissue using proteolytic enzymes fucking up blood vessels so baby can have some. day 8ish

what are lacunae

areas that hold maternal blood for baby. come from vacuoles that fuse. pop up around day 9

what happens like day 10

blastocyst is well embeded in endometrium. the hole left is closed up by closing plug (blood clot)

when do lacunar networks form and what do they contain

day 11. fusion of nearby lacunae. filled with embryotroph