Embryology Unit 3

smallest

mammalian eggs are among the — in the animal kingdom

fimbriae

egg is swept into the oviduct by —

ampulla

fertilization occurs in — of oviduct

24

cleavage occurs — hours after fertilization in the ampulla, the egg continues to the uterus

rotational, meridional, equatorial

mammalian zygotes undergo — cleavage where the first cleavage is — division and the second is both (prev) and —

asynchronous

mammalian blastomere division is —, the number of cells does not increase exponentially

8

zygotic genes in humans are activated by the # cell stage

compaction, E-cadherin, tight, gap

blastomeres huddle together and express — allowing for the formation of — and — junctions, this allows for congregation, communication, and cooperation of cells

morula

compacted 8-cell stage forms the 16-cell — →smaller internal cells surrounded by larger external cells

trophoblast, ICM

in the morula the external cells are — cells and the inner cells from the — (this is the first differentiation event in mammalian development)

blastocyst, blastocoel

the inner cell mass is positioned on one side of the embryo and is called the —, the internal empty cavity is called the —

decidua

during the peri-implantation period there is a restructuring of the maternal anatomy to accommodate the growing embryo, the trophoblasts of the embryo induces formation of maternal —

posterior, endoderm, notocord

mammalian gastrulation begins at the — end where the primitive streak arises, hensen’s node forms at the anterior end where cells give rise to the — and —

develop, DVE, AVE, Nodal, cerberus

A-P axis set up begins when embryo begins to —: as the embryo elongates, the longer portion forms — (cells farthest away from BMP signaling), cells migrate to — which forms where BMP and — is least present because it expresses — that blocks Nodal

body patterning

Hox genes are involved in — — and has multiple varients

ribs

Hox10 KO in mice causes the lumbar vertebrae to develop —

lumbar

Hox11 KO causes sacral vertebrae to become — vertebrae

conceptus

the embryo is classified as — from zygote to birth

preimplantation embryo

the embryo is classified as — — before implantation

embryo

—: 8 weeks of development after fertilization

fetus

—: from week 9 to birth

fertilization

before 1965, conception was considered to start at —

implants

after 1965, conception was redefined to be when the embryo — in the uterine wall

14

gastrulation begins at day # and is when twinning is no longer possible (some say this is when the embryo is considered an individual person)

granulosa

— follicular cells: cumulus cells that form tight adhesions with oocyte

corona radiata

— —: innermost layer of cumulus cells

theca, aromatase

— cells: produce androgen precursor (—) needed for estrogen production

granulosa

during ovulation, the oocyte with the corona radiata is ejected to the uterus, — cells remain behind and make progesterone

LH, FSH

ovulation is regulated by — and —

meiosis 2

LH stimulates ovulation, — — and puberty

granulosa, EGFR, GVBD, adhesions

During ovulation: LH binds to — cells (EGF receptors) → release of EGF-like peptides

LH binds to — stimulating — causing break down of the nuclear membrane advancing the oocyte to metaphase 2

cumulus granulosa cells lose — and become loosely linked to the oocyte allowing the oocyte to be ejected

immune system

the luteal phase causes deactivation of the — — in the uterine lining

corpus luteum

the ejected oocyte leaves behind the — — which produces progesterone

fimbriae

the ovum is swept into the oviduct(fallopian tube) by uterine —

24-48

male ejaculation releases ~40 million sperm, they reach the oviduct in # hours

90

first cell division (cleavage) occurs about # minutes after pronuclei meet

fertilization, cleavage, MZT, independently, compaction, visible

first 5 days of human embryogenesis:

day 1: —

day 2: first —, — occurs as early as 4-8 cell stage 

day 3: ~8 cells embryo is acting —

day 4: —, blastomeres flatten to form spherical shape

day 5: cell layers are —, trophoblast, ICM, and blastocoel

hatching, Na+, water

on day 6, — occurs, embryo leaves the zona pellucida: trophoblast cells pump — out causing — to fill the blastocoel

ovulation, reproductive, thickening, restructuring, uNK

preparation for pregnancy involves: —, sperm interactions with — tract environment, during the luteal phase of the uterine cycle there is a — of the endometrium and a local — of the immune cells in the uterus, progesterone secretions promote — cell maturation protecting the embryo from the mother’s immune system

cooperative

implantation is a — event between the embryo and mother

positioning, attachments, penetrate, restructuring

major steps of human embryonic implantation: apposition, — blastocyst appropriately for implantation; adhesion, blastocyst forms — with uterine epithelial cells; progression, trophoblast cells — epithelial layer and embed in uterine wall; decidualization, — the uterine environment in order to intake the embryo

ICM, L-selectin, Muscin-1, LIF, histocompatibility

human embryo implantation part1: embryo is positioned with — facing the uterine wall, microvilli on the uterine wall have — ligands (allow for positioning and adhesion to occur) and —# (blocks binding and implantation), (prev) is downregulated by — to promote attachment site, trophoblasts change their — proteins to hide from the mother’s immune system by downregulating their major histocompatibility

cytotrophoblast, projections, syncytiotrophoblast, chronic gondatropin, BMP2, implantation, implanted

human embryo implantation part2: — develop from original trophoblast cells and produce lamellipodia (— that allow the embryo to move in), — (multinucleate cells) arise from (first) cell divisions and secrete hormones such as — — (allows corpus luteum to be maintained during pregnancy) and — (activates MMP secretion and angiogenesis), MMPs break down EC matrix during —, stromal cells from the mother secrete factors that aid in transformation of — tissue and decidual cells

uNK, neutrophil, communication

how is the blastocyst not rejected and destroyed by the maternal immune system? progesterone secretions activate — cells that release cytokines that block — invasion, maternal and fetal cells — to prevent rejection of embryo

gastrulation

after implantation, — begins

prechordal plate, thickening, brain, eye, allantois

about 21 days post fertilization, the — — forms and is indicated by anterior mesodermal —, this structure later becomes anterior structures including the —, skull, and — muscles

the allantoic bud forms the — that later becomes the umbilical cord

arteries

during gastrulation, syncytiotrophoblasts remodel uterine — to create placental blood supply

infertility, aneuploidy, twinning, disorders, disruptors

alterations to normal pregnancy include: —, —, —, developmental —, developmental —

motility, hormone

male infertility can be caused by sperm —, — issues, testicular disorders

age, PCOS, thyroid

female infertility can be caused by —, —, endometriosis, — disorders, hormonal issues

aneuploidy

when a person has 2 few or 2 many chromosomes due to miotic nondisjunction, increases in likelihood with maternal age. likely due to protein breakdown at centromeres

twinning

first the egg is fertilized, then there is early blastomere separation either before or after formation of trophoblast or anion

genetic, congenital, chromosomal, pleiotropic, ART, environmental, stochastic

developmental disorders can be caused by — mutations such as: — anomalies leading to a particular syndrome, caused by a — or — event, or the use of —; — mechanism and — events can also play a role

brains, adhesion, oxidative

fetal alcohol syndrome: children present with dramatically smaller —, can deter cell — and increase — stress

endocrine, chemicals, synthetic, block

some developmental disruptors are — disruptors, which is when — disrupt the normal processes directed by hormones, these (prev) act like — hormones and can enhance the effect of the endogenous hormone or — natural hormone activity

BPA, meiosis, reversion

— used in the production of plastics, top 50 chemicals, disrupts — and causes sex — in frogs

neural tube, epidermal, brain, organogenesis

after implantation begins — — formation, — formation, — and axonal growth, and —

Santiago Ramon y Cajal

the father of modern neuroscience, worked with Golgi and won a Nobel prize for their work on the structure of the nervous system

silver, Cajal, reticular, individual

Golgi developed — staining to allow for visualization of neurons, — used that to disprove — theory and showed that neurons are —, specialized cells of the nervous system

arborization

the idea that neurons are single cells with branching structures

network

neural dendrites develop an exquisite branching — throughout the body

neural tube, brain, neural crest, migration

what are the 3 main processes of neural arborization? — — formation, — growth, — — cell —

neurulation, ingressing, anterior, posterior, BMP, epidermis

— first step after gastrulation, at the anterior most portion cells are — even before gastrulation, the grove closes — to —, neural tube closure is governed by ventral — from —

proliferation, anteriorly, ingression, cavitation, posteriorly, transition, thoracolumbar

primary neurulation involves —, invagination, separation and occurs —, secondary neurulation involves —, aggregation, — and occurs —, junctional is the — zone that spans the — region in humans

elongation, invagination, convergence, closure, signaling

overview of primary neurulation in chicks: — and folding of neural plate, — of neural plate, — of neural folds, — of neural tube this all allows the formation of the notochord as a — center

elongation, surface area, autonomously, presumptive neural

the first step of primary neurulation in chicks is —: there is an increase in the — — of tissue, cell proliferation occurs —; — — crest cells undergo proliferation

folding, MHP, notochord, midline

the secondary step of primary neurulation in chicks is —: as the tissue bends the — forms, folding of the neural plate makes contact with the —, the floor plate of the neural groove establishes the — axis

elevation, folds, MHP, apical, actin/myosin, faster

the third step of primary neurulation in chicks is — of neural —: the floorplate/— undergoes — constriction by decreasing the (prev) surface area by constricting the —/— filaments in their cytoskeleton, in the neural groove cell proliferation is — than in the MHP

convergence, neural folds, DLHP

the forth step of primary neurulation in chicks is —: tissues of the — — are pushed together by —

Closure, fuse, cadherins, tube, crest

the fifth step of primary neurulation in chicks is —: the neural crest cells — together, — play a critical role in the closure and separating of tissue, neural — forms and neural — cells disperse to form neurons, melanocytes, adrenal cells

morphogen, BMP, DLHP, apical, Noggin, BMP, DLHP, SHH, Noggin

neurulation signaling uses — gradients: in the outer ectoderm — blocks — and — constriction, in the neural fold — inhibits — so that constriction can occur/— can be expressed, cells closest to the notochord — is expressed and blocks —

BMP, SHH

DLHP exists only where there is low — and —

transition

the notochord is a signaling center and is a — structure

neural, inhibit

SOX are transcription factors that are — markers, the both turn on neural markers and — other fates

caudal epiblast, neural tube, Tbx6

Formation of neural tube: — — contains precursor cells for neural ectoderm and paraxial mesoderm, Sox-2 expressing precursor cells become — —, ingressing cells (that do not express Sox-2) express — to become paraxial mesoderm

extra neural tubes

if Tbx6 is inhibited, the cells form — — —

bidirectionally

anterior to posterior neural tube development can occur —

multiple, both

neural tubes have — closure points during development, the neural tube is “zipped up” in — directions

defects

failure to close the neural tube properly results in neural tube —

5

humans have # neural tube closure points

anencephaly

(NTD) when the brain is exposed to amniotic fluid and the neural tissue degrades

craniorachischisis

(NTD) complete neural tube failure to close

spina bifida

(NTD) spinal cord exposed and degrades, often results in paralysis at the waist down

zinc, p53

— depletion leads to widespread DNA fragmentation and apoptosis and deficiency may lead to stabilization of — which induces widespread apoptosis

synthesis, methylation, unknown, prevented, epigenetic

folate is known to be necessary for DNA — and regulating DNA —, the mechanism of folate activity in neural tube closure is —, but an estimated 25-30% of NTDs can be — with supplemental folate, DHFR and MTHFR convert folate to 5-methylTHF which is thought to have an — effect