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Embryology 1-4 wks

Stack #22819

Where do the PGC’s arise from? Epiblast
Where do the PGC’s migrate to first? Gut tube
What does the movement to the dorsal body wall stimulate next? Proliferation of epithelium and mesonephros
When are genital ridges formed? 6-12 weeks.
In males, when does spermatogenesis start? Puberty
Gametogenesis Process of meiosis and cytodifferation that converts germ cells into mature male and female gametes
What happens to the cells of the follicle just following puberty in females? They change shape. Become cuboidal.
When does the formation of the zona pellucida occur? When the primary follicle is formed
When does the surge of LH/FSH occur? After the formation of the secondary follicle
What is triggered in the female immediately after fertilization? Secondary oocyte resumes meiosis II producing definitive oocyte and 2 polar bodies
What produces HCG to support the corpus luteum in progesterone secretion? The embryo! Then the placenta takes over after 4th month.
Where does the morula travel to? What does it called now? Uterine cavity; blastocyst
morula The ball of blastomere cells divide, flatten, and reorganize together during compaction where a convex inner cell mass(becomes the embryo) and concave outer cell mass(becomes the placenta) are established
Blastocele Fluid filled Cavity formed by the morula while forming the blastocyst.
The blastocyst hatches from Zona Pellucida and implants, forming these two items…. Inner cell mass embryoblast
What days does the embryo differentiate into 2 layers? Days 7-8 Epiblast and Hypoblast
What forms the syntiotrophoblast? What day? Trophoblast cells at embryonic pole that loose cell membranes and syncycium day 6-9
What forms the cyntotrophoblast? Trophoblast cells at abembryonic pole.
What do the cyntrophoblast secrete? Hydrolytic enzymes
Bilaminar germ disk After the epiblast and hypoblast differentiate from each other in the embryoblast, the embryo is called a bilaminar (two-layered) germ disc.
When is amniotic cavity formed? What are the surrounding cells called? day 8, amnioblasts
What is the major event within the synctiotrophblast that occurs on Day 9? Vacuoles (trophoblastic lacunae) open within the syncytiotrophoblast and anastome with maternal capillaries.
When is heusers membrane formed?What is it formed from? Day 12, Hypoblast cells migrating over cytotrophoblast
Around day 12, the blastocyst is now called Primary yolk sac
What is the acellular material formed between the heusers membrane and cyntrophoblast called? Extraembyronic reticulum
The cyntrophoblast develops extensions that dvelop into the syntiotrophoblast. The extensions grow into the ____________ and are called ______ Lacunae; Primary stem villi
What becomes the placenta? The primary stem villi
What converts primary into secondary villi? Extraembryonic mesoderm
When does the chorionic cavity expand, separating the amnion from the cytotrophoblast? Week 2
What is the fate of the primary yolk sac? (around day 12-13) The old primary yolk sac is displaced toward the abembryonic pole. It ultimately degenerates into a group of exocoelomic vesicles which ultimately disappear.
What day is primitive streak complete? Day 16
Gastrulation process of epiblast ingress through the primitive streak forming the primary germ layers
The fundamental anatomical positions of the embryo are established by the ____ Primitive Streak
What four things happen once the two mesodermal structures are developed (prechordal plate and notochordal process)? 1. Lateral mesoderm become paraxial, intermediate, and lateral plate mesoderm. 2.Primitive streak regressing caudally 3.Prechordal plate and cranial portion of the notochordal process secrete 4. cells differentiate into neural plate
Which somitomeres develop into somites? All but first 7.
What day is notochordal process completely formed? Day 20
When do the blood vessels develop? Week 3
Describe notochordal process’ transformation to solid rod 1.Ventral floor of tube fuses w/ endoderm 2.tube unzippers ventrally starting @ primitive pit 3.notochordal processes converted to notochordal plate 4.completely detaches from the endoderm and retreats back: notochord
The lateral plate splits into parietal and visceral layers….What does the parietal layer line?What does the visceral layer line? 1. lines the intraembryonic cavity 2. visceral lines the outer surfaces of the visceral organs
Neurulation conversion of neural plate to neural tube
Prosencephalon forebrain) portion cranial to flexure
Rhombencephalon hindbrain) portion caudal to flexure
Describe neurulation EDIT
When is Closure of the caudal neuropore day 26
When is bidirectional Closure of the cranial neuropore at site of future forebrain day 24
When does primitive streak disappear? day 26
What are the two steps of Secondary neurulation? 1. Central mass of caudal eminence forms into a solid neural cord. 2. Forms lumen that joins with the neural canal. Caudal end of neural tube completed at apprx 8 weeks
Which way does cytodifferentiation proceed? Caudally and cranially
what is the order for cytodifferentiation of neural tube? Neuroepithethial cells surround; Neuroblasts migrate; Glioblasts migrate; Neuroepithelial cells differentiate
Differentiation of neural tube Dorsal and ventral columns begin to form in the mantle layer of the spinal cord at end of 4th week. Fundamental morphology of spinalcord established
Implantation occurs during which week? First
What does the trilaminar germ disk differentiate into? Embryo
The urinary system and parts of the genital system develop from intermediate mesoderm
The hormone responsible for ovulation is luteinizing hormone or FSH
What is surrounded by the zona pellucida/ The morula
Primary oocytes begin the first meiotic division before birth, but only get so far as an uncompleted: prophase
The sex of the embryo is determined at time of fertilization
The amniotic cavity develops within the epiblast
The primordial germ cells leave the yolk sac and migrate along the dorsal mesentery to reach the genital ridges by ameboid movement
In oocytes, the second meiotic division is completed When?? following fertilization
The bilaminar germ disc (embryonic disc) consists of: epiblast and hypoblast
During the process of meiosis, the DNA replicates itself when? prior to the first meiotic division
Gonadotropin releasing hormone (GnRH) is produced by the hypothalamus
The _______________ of the syncytiotrophoblast fuse to form spaces that will be filled with maternal blood trophoblastic lacunae
The first cavity to appear in the embryo after fertilization is the: blastocyst cavity
The process that leads to the formation of the three germ layers is called gastrulation
The portion of the early embryo that gives rise to essentially all of the fetus is the: epiblast
The amniotic cavity develops within the: epiblast
After ovulation, the walls of the remaining Graafian follicular structure collapse and form a glandular structure, the: corpus luteum
A polar body is the result of: unequal division of the cytoplasm in oocytes during meiosis
Contact of the oocyte plasma membrane by a sperm and fusion of their cell membranes induces alteration of the zona pellucida so that no more sperms can penetrate it. This is mediated by release of the contents of: cortical granules of the oocyte
Cells that give rise to the gametes in both males and females originate in the epiblast
Spaces developing in the extraembryonic reticulum become confluent to form the chorionic cavity
Human development is complete when the fetus is delivered at birth...true or false? False
Primary chorionic villi are developed as projections of the _______________into the syncytiotrophoblast. cytotrophoblast
describe the origin of primordial germ cells (PGCs) and the importance of the yolk sac for PGCs PGCs originate in the epiblast, migrate to yolk sac and later migrate to the body cavity
HCG acts on the corpus luteum to maintain production of progesterone
Which cells are the surface cell layer of the blastocyst? the trophoblast cells
The chromosomal abnormality of Down syndrome (trysomy 21) can be detected by A karyotype analysis of cells isolated by amniocentosis
Blastocyst hatching occurs before or after implantation? before
What is the embryo-derived cell layer that forms the interface with the endometrium? Syncytiotrophoblast
What is the embryo cell layer that is the source of the cells that form the yolk sac? Hypoblast
What is the embryo cell layer that is the source of the cells that form the amniotic cavity? epiblast
where gastrulating cells migrate out of the epiblast primitive streak
The two main types of cells formed by the gastrulating cells are ________________ Definitive endoderm and primary endoderm
The notocord is formed by cells that gastrulate through primitive node
What is the origin of the paraxial mesoderm, intermediate mesoderm and the lateral plate mesoderm? Epiblast cells that gastrulate laterally through the primitive streak
What are condensations of cells that form in the paraxial mesoderm and usually develop further to form somites? somitomers
The sclerotome, myotome, and dermatome arise directly from somites
The cells of the neural plate have a distinct epithelial structure called The neuroepithelium or neuroectoderm
structures formed by cells of the sclerotome? vertebre
structures formed by cells of the myotome? muscles
The folding of the neural plate to form the neural tube is called ____________ Neurulation
The dermal bones of the skull are formed by cells from Cranial neural crest
The sensory neurons of the dorsal root ganglia are formed by cells from Spinal neural crest
Neurons of the dorsal root ganglia project axons to which part of the spinal cord? The dorsal columns
The costal processes of the vertebrae give rise to ribs
Somatic motor neurons reside in ___________ ventral columns
Which dietary component is recommended in order to reduce the risk of neural tube defects? folic acid
The ventral columns of the spinal cord are induced by sonic hedgehog (SSH) from the floor plate to for what type of neuron? somatic motor nneuron
What is formed by cells of the dermatome? connectie tissue
What hormone is produced by cells in the pituitary gland? fsh
What is the early embryo cell layer that is the source of the cells that form the embryo proper, but not the extraembryonic tissues such as the yolk sac? epiblast
Put the following into order: a.formation of sex cords b.PGC’s differentiate in endodermal layer c.Genital ridges appear d.PGC’s migrate via dorsal mesentery to the dorsal body wall B D A C
Put these in order of occurance: a.Spermatogonia B b.Secondary spermatocyte c.Acrosome reaction d.Spermatid e.Spermatogonia A f.Primary spermatocyte g.Spermatozoa h.Spermatogonal stem cells i.Capatation H, e, a, f, b, d, g, I, c, Spermatogonal stem cells; Spermatogonia A; Spermatogonia B; Primary spermatocyte; Secondary spermatocyte; Spermatid; Spermatozoa; Capitation; Acrosome reaction;
Put in order of occurance a.oogonia b.primary oocyte c.ovarian follicle d.development of primordial follicles e.secondary follicle f.secondary ooctye g.Meiosis I resume h.Pre ovulatory follicle i.Meiosis II j.Primary follicle Ovarian follicle; Oogonia; Primary oocyte; Development of primordial follicles; Primary follicle; Secondary follicle; Pre ovulatory follicle; Meiosis I resumes; Secondary oocyte; Meiosis II;
Put in order: a)epiblast cells displace hypoblast creating definitive endoderm. b)Primitive streak migrates bt epiblast and hypoblast c)Third germ layer formed d)Prechordal plate developed e)Epiblast cells next to Prim Streak proliferate Epiblast cells proliferate; Primitive Streak migrates; Epiblast displace hypoblast; Third germ layer forms Prechordal plate;
Created by: tpingel