Flashcards in Exam 1 Review Deck (115):
process by which a cell or part of an embyro becomes restricted to a given developmental pathway. (no longer pleuripotent)
complex of changes involved in progressive specialization of structure and function, often resulting in the formation of luxury molecules
permanent increase in mass; hyperplasia = increase in cell number; hypertrophy = increase in cell size
generation of form or assumption of new shape
an effect one embryonic tissue (inductor) has on another (responder) such that the development course of the responding tissue is qualitatively changed from what it would have been in the absence of the inductor.
process by which different tissues are brought together and combined to form organs and tissues
following fertilization, when do primordial germ cells 1st appear?
24 days after fertilization; found in endodermal layer of yolk sac
migration route of PGCs into developing gonads from yolk sac
yolk sac --> hindgut epithelium; through dorsal mes; into developing gonads
abnormal number of chromosomes; monosomy/trisomy; could be a result of non disjunction
changes in the number of complete sets of chromosomes; mono- di- and polyploidy
2 chromatids; begin to coil
what is the genetic make up during prophase I?
when does the synaptonemal complex form?
max coiling; tetrads; cross over begins
when are the chiasma well defined?
cross over complete; terminalization; spindle app in place; nuclear membrane disrupted
tetrads line up along equatorial plate; centromeres don't divide
when do homologs move to opposite poles?
cytokenesis; nuclear membrane forms; spindle app disassembles; chromosomes recoil
genetic make up during prophase II
chromosomes condense; nuc. membranes dissapear; spindle app reforms; haploid
when is the second time that chromosomes line up on the equatorial plate?
centromeres divide; chromosomes move to opposite poles; chromosomes have 1 chromatid
chromosomes uncoil; cytokenesis complete; nuc. membrane refroms
what is the result of meiosis?
increase in cell numbers (sometimes); non-identical daughter cells (4); daughter cells haploid
how does the number of oocytes change from early development to puberty?
7 million at embryonic midterm, 2million remain at birth, 40,000 survive to puberty, 400 will be ovulated
what factors lead to meiotic arrest at the diplotene stage?
increased concentration of cAMP inactivates MPF and leads to meiotic arrest
what maintains increased concentration of cAMP?
cGMP inactivates phosphodiesterase 3A which prevents cAMP --> 5' AMP
role of circulating FSH
stimulates granulosa cells to produce estrogen
what causes meiosis to resume the first time?
LH surge by shutting down gap junctions b/w granulosa cells and oocyte
converts testosterone to b-estradiol
B-estradiol / estrogens
stimulate formation of LH receptors on granulosa cells
what do LH receptors secrete?
when does ovulation occur in the ovarian cycle?
day 14 of ovarian cycle
what is the stimulus for ovulation?
rise in levels of FSH and sharp rise in LH
what components of the graafian follicle form the corpus luteum?
residual theca and granulosa cells proliferate and form a large glandular strucutre called the corpus luteum
fate of corpus luteum in absence of fertiliation?
regresses and tissue is replaced by corpus albicans
proliferation phase of endometrial cycle
thickness increases by day 14; blood vessels and glands grow; due to an increase in estradiol secreted by granulosa cells
secretory phase of endometrial cycle
levels of estrogen decrease and endometrial growth stops; mucous glands begin secretion; spiral arterioles expand; controlled by rising levels of progesterone secreted by granulosa and thecal cells
describe graafian follicle immediately prior to ovulation
mature; oocyte arrested in diplotene of prophase I; expansion of follicle by LH FSH; completion of meiosis I; 2nd arrest at metaphase II; formation of stigma
age of embryo from time of fertilization
age of embryo from start of mother's last mentrual period. 2 weeks greater than fert. age
what hormone is necessary for the egg rapid transport through the isthmus?
what contributions are made to semen by the seminal vesicles?
fructose and prostaglandins
what contributions are made to semen by the prostate glands?
citric acid, Zn, Mg, phosphatases
what is the optimal pH for sperm motilit?
6 - 6.5
what is the pH of the upper vagina?
4.3 -> 7.2 (buffered by seminal fluid)
what is the pH of the cervix?
where does fertilization occur?
what is the purpose of capacitation?
required for sperm to undergo acrosomal rxn
where does capacitation occur?
inside uterine tube in isthmus
explain how sperm penetrates corona radiata
sperm and acrosome fuse; its membrane fragments release hyaluronidase that breaks down HA in the intracell matrix b/w corona radiata cells; swimming movements help also
what is the function of ZP3?
mediates attachment of the sperm to the XP and stimulates the acrosomal rxn
fast block to polyspermy
rapid depolarization of plasmalemma; -70 to +10mV w/i 2-3 seconds; prevents poly spermy and allows time for slow block
slow block to polyspermy
release of polysaccharides from cortical granules; polysaccharide enters perivitelline space and become hydrated; produces a swelling that increases width of space
role of phospholipase C zeta in metabolic activation of egg
introduced by sperm causing release of Ca+ in egg cytoplasm which initiates blocks to polyspermy, stimulates increase in egg respiration and metabolism
nuclear material of the head of the spermatozoan or oocyte after oocyte has been penetrated by sperm; normally carries haploid chromosomes
single-celled stage at which male and female pronuclei have fused together and share a common membrane, establishing the diploid chromosome
forms extraembryonic strucutres including placenta
forms embryo proper plus some extraembryonic strucutres (yolk sac and amnion); embryonic pole = pole where ICM is located
genetic control in invertebrates and non-mammals
early cleavage control is through gene products transcribed form maternal genome
genetic control in mammals
maternal gene products are produced but degreaded by 2 cells stage; by 4 cell stage, most transcription is via the embryonic genome
Cdx-2 role in differentiation
essential for trophoblast cell differentiation; antagonist toward Oct-4
Oct-4 role in differentiation
expressed in developing oocytes and zygote; required to permit cleavage to proceed to 2 cell stage; in all morulas
Nanog role in differentiation
produced by inner cells in late morula stage; maintains integretiy of ICM w/ Oct-4
what is the differentiation of ICM w/o Nanog
differentiation of ICM w/0 Oct-4
Sox-2 role in differentiation
1st expressed in 8 cell stage; w/ Oct-4, helps control regulation of genes involved in differentiation
differential gene expression depending on whether a chromosome is inherited by the male or female parent; refers to the observation that expression of certain genes derived from the egg differs from the expression of the same genes derived from the sperm; due to DNA methylation differences in sperm/egg
small hands and feet, short stature, poor sexual development, mental retardation, big apetide; mutation is always inherited from father
what chromosome is deleted in prader willi and angelman syndrome
long arm of chromosome 15
frequent laughter, uncontrolled muscle movement, lg. mouth, unusual seizures; mutation is always inherited from mother
what are barr bodies?
inactive X chromosome after X inactivation by Xist
ability of embryo to compensate for removal of structures or addition of strucutres; cells aren't fized, can respond to environmental cues
fraternal; fertilized from 2 different eggs
identical; 1 fertilzed egg; basis of conjoined twins
what's Bateson's Rule?
when duplicated strucutures are joined during critical developmental stage 1 stucuture is the mirror image of the other
surrounds developing embryo until it reaches the uterus and shedding is acomplished through blastocyts hatching
what is blastocyst hatching?
small region of ZP dissolved and blastocyste emerges from hole
where do ectopic pregnancies most commonly occur?
highly conserved region of 60 aa; helix loop helix
180 nucleotides in the gene that encode the homeodomain
Zn finger motif
have Zn bound to polypeptide chain that causes chain to form finger like projections that can be inserted into DNA helix
what are 2 Zn finger domains
Sox: high mobility group domain that binds MINOR groove; include SRY
WT1: important for devpt. of embryonic kidney and adult kidney
helix - loop - helix
short stretch of aas where 2 alpha helices are separated by an aa loop; involved in homodimerization or heterodimerization
maternal effect genes aka egg polarity genes
establish dorsal-ventral and ant-post axes in fly
dorsal-ventral egg polarity genes
dorsal, cactus, toll
anterior posterior egg polarity genes
bicoid, nanos, hunchback
no genetic maternal effect b/c transcribed after fertiliation; regulated by bicoid and nanos proteins gradients
three categories of segmentation genes
Gap genes; pair-rule genes; segment-polarity genes
delet adjacent segments - hunchback
pair rule genes
delete same part of pattern in every other segment
segment polarity genes
affect polarity of segment; patched, smoothened, wingless, hh, gooseberry
contian homeobox; determine the identiry of individual segment; products of homeotic genes activate other genes that encode segment-specifc characteristics
consists of a large proregion and bioactive region; ex: BMP - inhibits other processes in embryo
interaction w/ heparan proteoglycans in receptor complex; regulation at membrane of responding cell via transmembrane proteins; regulated heavily
related to segment polarity molecule in Dros.; include desert, indian, shh
related to seg. polarity genes; interacts w/ components of extracellular matrix; plays different roles in various vert. classes
dominant cell expressed delta signaling molecules on its cell membrane; delta binds to notch receptors on neighboring cells and represses their genes
role of nanog in establishment of epiblast and hypoblast
early expression of Nanog from ICM = determined to become epiblast
role of gata 6 in establishment of epibast/hypoblast
cells entering ICM later express Gata-6 and are destined to become hypoblast cells - may be induced by FGF-4 secretion
what roles might Wnt and TGF-B play in the formation of the primitive streak?
possibly induce it
what are the 3 classical molecular markers expressed by nodal cells?
nodal, goosecoid, foxa-2
what are the bottle cells and what's their role in gastrulation
cells that assume a bottle shape due to microtubules and thrust themselved through primitve groove into space and become free = mesenchymal and will reform other layers (mesodermal layers)
describe the role of E-cadherin and N cadherin in epithelial - mesenchymal transtion
before induction: ectoderm expresses E cadherin and N-CAM; after nueral tube induction: overlying ectoderm only expresses E cadherin; neural tube ectoderm only expresses N CAM and N cadherins
originates from ant. visceral endoderm and inhibits development of posterior strucutres
originates from ant. visceral endoderm; targets and blocks Wnt; inhibits development of posterior strucutres
what 2 signaling molecules are responsible for blocking the development of posterior strucutres in early primitve streak?
Cerebrus like and DKK-1
what are the effects of foxa-2 on the early primitive streak?
establishment of prim. node; initiates notochord funtion; establishes midline strucutres cranial to node
in late primitive streak stage, what SM is necessary for normal head formation?
in the late primitive streak, what signaling molecules released from primitive streak activate Hox genes?
RA; Wnt; FGF; Nodal;
process by which a cell or part of embryo becomes restricted to a given developmental pathway. The point at which a cells becomes committed to a specific cell line
a complex of change involved in the progressive specialization of strucutre and function; often resulting in the formation of luxury molecules
what's the first sign of asymmetry in early development?
beating of cilia around the primitive node