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Embryology 1-4 wks
Stack #22819
| Question | Answer |
|---|---|
| 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
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