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| =Week 1 and 2=
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| == Introduction ==
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| Following fertilization the first week is a series of rapid cell divisions, still contained within the zona pellucida, and still floating and being propelled within the uterine tube towards the uterine body. At the end of the first week and within the second week the process of implantation and early differentiation of cells that will form the embryo and the placenta.
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| {|
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| | <wikiflv width="600" height="200" autostart="true" repeat="true">Week1_001.flv|File:Week1_001 icon.jpg</wikiflv>
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| | This animation shows the first week of human development following fertilization.
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| (More? [[Development Animation - Week 1]])
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| |}
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| :Lecture Archive: [[2010_Lecture_3|2010 Lecture]] | [[2009_Lecture_3|2009 Lecture]]
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| [[Image:Week1_summary.jpg|thumb|Week 1 Human Development Overview]]
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| [[File:Inner_cell_mass_cartoon.jpg|thumb|Inner cell mass]]
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| [[Development_Animation_-_Week_1|Movie - Week 1 Cell Cleavage]] | [[Carnegie stage 1]]
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| == Morula ==
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| [[Carnegie stage 2]]
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|
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| * about '''day 4''' is a solid ball of 16-20 cells with peripheral cells flattened against zona pellucida
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| * compaction occurs forming a cavity and leading to the next blastocyst stage
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| :'''Links:''' [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=hmg.figgrp.928 Figure 8.19. Changes in DNA methylation during mammalian development]
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| ==Blastocyst==
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| [[Carnegie stage 3]]
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| [[Image:CSt3.jpg|thumb|300px|Hatching Blastocyst]]
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| * about '''day 5''' have 2 identifiable cell types and a fluid-filled cavity (blastoceol)
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| ** '''trophoblast layer''' - peripheral flattened cells, forms the placenta and placental membranes
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| ** '''inner cell mass''' - embryoblast, mass of rounder cells located on one wall of the blastocoel, forms entire embryo
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| ===Blastula Cell Communication===
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| Two forms of cellular junctions [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=mboc4.figgrp.3927 Figure 21-69. The blastula]
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| * '''gap junctions''', allow electrically couple cells of epithelium surrounding a fluid-filled cavity
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| *''' tight junctions''', close to outer surface create a seal, isolates interior of embryo from external medium
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| '''Blastocyst Hatching''' - zona pellucida lost, ZP has sperm entry site, and entire ZP broken down by uterine secretions and possibly blastula secretions.
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| '''Uterine Glands''' - secretions required for blastocyst motility and nutrition
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| == Week 2 - Implantation ==
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| [[Development_Animation_-_Implantation|Movie - Implantation]]
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| The second week of human development is concerned with the process of implantation and the differentiation of the blastocyst into early embryonic and placental forming structures.
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| * implantation commences about '''day 6 to 7'''
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| * '''Adplantation''' - begins with initial adhesion to the uterine epithelium
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| ** blastocyst then slows in motility, "rolls" on surface, aligns with the inner cell mass closest to the epithelium and stops
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| * '''Implantation''' - migration of the blastocyst into the uterine epithelium, process complete by about '''day 9'''
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| * '''coagulation plug''' - left where the blastocyst has entered the uterine wall '''day 12'''
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| '''Normal Implantation Sites''' - in uterine wall superior, posterior, lateral
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| ===Endometrial Receptivity===
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| In humans, receptivity occurs 6 days after the post-ovulatory progesterone surge and lasts about 2 to 4 days. A similar "receptivity window" occurs following fertilization in other species: rat day 5 and mouse day 4.5. Many studies have looked into identifying markers for this receptivity period both to optimise and to block this process.
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| ===Abnormal Implantation===
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| [[Image:Tubal pregnancy.gif|thumb|Ectopic tubal pregnancy]]
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| Abnormal implantation sites or Ectopic Pregnancy occurs if implantation is in uterine tube or outside the uterus.
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| * sites - external surface of uterus, ovary, bowel, gastrointestinal tract, mesentry, peritoneal wall
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| * If not spontaneous then, embryo has to be removed surgically
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| '''Tubal pregnancy''' - 94% of ectopic pregnancies
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| * if uterine epithelium is damaged (scarring, pelvic inflammatory disease)
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| * if zona pellucida is lost too early, allows premature tubal implantation
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| * embryo may develop through early stages, can erode through the uterine horn and reattach within the peritoneal cavity
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| {|
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| | [[File:Tubal_pregnancy_historic.jpg|200px]]
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| | [[File:Abnormal_implantation_sites.jpg|200px]]
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| |}
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| :'''Links:''' [[Abnormal_Development_-_Ectopic_Implantation|Ectopic Pregnancy]] | [[Ultrasound_-_Ectopic_01|Movie - Ectopic pregnancy ultrasound]]
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| == Uterus ==
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| <gallery>
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| Image:Uterus proliferative phase.jpg|Uterus proliferative phase
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| Image:Uterine gland proliferative phase.jpg|Uterine gland proliferative phase
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| Image:Uterus secretory phase.jpg|Uterus secretory phase
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| Image:Uterine gland secretory phase.jpg|Uterine gland secretory phase
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| </gallery>
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|
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| * Endometrium - 3 layers in secretory phase of menstrual cycle: compact, spongy, basal
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| * Myometrium - muscular layer outside endometrium, contracts in parturition
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| * Perimetrium - tunica serosa of the uterus continuous with the peritoneal wall
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| ===Endometrial Layers===
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| * Compact - implantation occurs in this layer, dense stromal cells, uterine gland necks, capillaries of spiral arteries
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| * Spongy - swollen stromal cells, uterine gland bodies, spiral arteries
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| * Basal - not lost during menstruation or childbirth, own blood supply
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| ===Decidual Reaction===
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| * occurs initially at site of implantation and includes both cellular and matrix changes
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| * reaction spreads throughout entire uterus, not at cervix
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| * deposition of fibrinoid and glycogen and epithelial plaque formation (at anchoring villi)
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| * presence of decidual cells are indicative of pregnancy
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| Cervix - at mouth of uterus, secretes mucus (CMP), forms a plug/barrier, mechanical and antibacterial
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| Vascular - increased number of blood vessels
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| ===Decidua===
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| The endometrium becomes the decidua and forms 3 distinct anatomical regions (at approx 3 weeks)
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| * Decidua Basalis at implantation site
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| * Decidua Capsularis enclosing the conceptus
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| * Decidua Parietalis the remainder of uterus
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| ** Decidua Capsularis and Parietalis fuse eventually fuse and uterine cavity is lost by 12 weeks
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| === Uterus Abnormalities ===
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| '''Endometriosis''' endometrial tissue located in other regions of the uterus or other tissues. This misplaced tissue develops into growths or lesions which respond to the menstrual cycle hormonal changes in the same way that the tissue of the uterine lining does; each month the tissue builds up, breaks down, and sheds. [http://embryology.med.unsw.edu.au/wwwhuman/mcycle/Mcycle.htm#Endometriosis Endometriosis]
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| == Bilaminar Embryo ==
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| [[Development_Animation_-_Chorionic_Cavity|Movie - Week 2 Bilaminar Embryo]]
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| [[Image:Pregnancy test.gif|thumb|Pregnancy Test Kit]][[Image:Ovary_corpus_luteum.jpg|thumb|Ovary corpus luteum]]
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| * about '''day 8 to 9'''
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| The outer trophoblast and inner embryoblast layers now both differentiate to form two distinct cellular layers. The trophoblast layer forms the syncitotrophoblast and cytotrophoblast layers. The embryoblast (inner cell mass) forms the epiblast and hypoblast layers. This early stage of embryo development is referred to as the bilaminar embryo.
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| ===Syncitiotrophoblasts===
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| * secrete proteolytic enzymes, enzymes break down extracellular matrix around cells
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| * Allow passage of blastocyst into endometrial wall, totally surround the blastocyst
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| * generate spaces that fill with maternal blood- lacunae
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| * secrete Human Chorionic Gonadotropin (hCG), hormone, maintains decidua and Corpus Luteum, basis of pregnancy diagnostic test, present in urine is diagnostic of pregnancy
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| ** Later in development placenta will secrete hCG
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| '''MH''' - more information in lecture 4 and laboratory.
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| ===Human Chorionic Gonadotropin===
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| * levels peak at 8 to 10 weeks of pregnancy, then decline and are lower for rest of pregnancy
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| :0-1 week: 0-50 mIU/ml
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| :1-2 weeks: 40-300 mIU/ml
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| :3-4 weeks: 500-6,000 mIU/ml
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| :1-2 months: 5,000-200,000 mIU/ml
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| :2-3 months: 10,000-100,000 mIU/ml
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| :2nd trimester: 3,000-50,000 mIU/ml
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| :3rd trimester: 1,000-50,000 mIU/ml
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| Non-pregnant females: <5.0 mIU/ml
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| Postmenopausal females: <9.5 mIU/ml
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| == Twinning ==
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| Twinning can be due to two separate fertilization events (dizygotic twins) or as an abnormality of a single fertilization (monozygotic twins) event during the early weeks of development.
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| ===Dizygotic Twinning===
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| Dizygotic twins (fraternal, non-identical) arise from separate [[F#fertilization|fertilization]] events involving two separate [[O#oocyte|oocyte]] (egg, ova) and [[S#spermatozoa|spermatozoa]] (sperm).
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| * In '''dizygotic twinning''' the genetic material is different and implantation and placentation is also different.
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| ===Monoygotic Twinning===
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| * In '''monozygotic twinning''' the genetic material is initially identical and degree of twinning will depend upon the timing (early to late) from separate fetal membranes and placenta to conjoined twins.
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| ** morula stage (diamniotic dichorionic), early blastocyst (diamniotic monochorionic), late blastocyst to bilaminar (monoamniotic monochorionic), bilaminar to trilaminar embryo (conjoined)
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| * Monozygotic twins are a unique research resource for comparing environmental effects on development and health.
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| * Congenital abnormality statistics for twins is generally increased in various conditions.
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| Monoygotic twins (identical) produced from a single [[F#fertilization|fertilization]] event (one fertilised egg and a single spermatazoa, form a single zygote), these twins therefore share the same genetic makeup. Occurs in approximately 3-5 per 1000 pregnancies, more commonly with aged mothers. The later the twinning event, the less common are initially separate placental membranes and finally resulting in conjoined twins.
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| {| class="prettytable" 100%
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| | width=10% | '''Week'''
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| | colspan="7" | Week 1
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| | colspan="7" | Week 2
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|
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| |-bgcolor="lightsteelblue"
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| | '''Day'''
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| | width=5% | 0
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| | width=5% | 1
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| | width=5% | 2
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| | width=5% | 3
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| | width=5% | 4
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| | width=5% | 5
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| | width=5% | 6
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| | width=5% | 7
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| | width=5% | 8
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| | width=5% | 9
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| | width=5% | 10
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| | width=5% | 11
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| | width=5% | 12
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| | width=5% | 13
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| | width=5% | 14
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| | ==2016== |
| | {| class="wikitable mw-collapsible mw-collapsed" |
| | ! ECHO360 Recording |
| |- | | |- |
| | '''Cell Number'''
| | | [[File:ECHO360_icon.gif|right|link=https://lectures.unsw.edu.au/ess/portal/section/5157_00900]] |
| | 1
| | [https://lectures.unsw.edu.au/ess/portal/section/8aefd634-898b-4cdd-bbd5-c6052c39b759 2015 Lecture 3] |
| | 1
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| | 2
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| | 16
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| | 32
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| | 128
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| | bilaminar
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| |-
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| | '''Event'''
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| | Ovulation
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| | fertilization
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| | First cell division
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| | Morula
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| | Early blastocyst
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| | Late blastocyst
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| Hatching
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| | Implantation starts
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| | X inactivation
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| |-
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| | [[File:Follicle 001 icon.jpg|50px]] | |
| | [[File:Early_zygote.jpg|50px]] | |
| | [[File:Human embryo day 2.jpg|50px]]
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| | [[File:Human embryo day 3.jpg|50px]]
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| | [[File:Human embryo day 5.jpg|50px]]
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| | [[File:CSt3.jpg|50px]]
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| | [[File:Week2_001 icon.jpg|50px]]
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| |-bgcolor="lightsteelblue"
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| | '''Monoygotic'''
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| '''Twin Type'''
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| | colspan="3" | Diamniotic
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| Dichorionic
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| | colspan="3" | Diamniotic
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| Monochorionic
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| | colspan="3" | Monoamniotic
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| Monochorionic
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| | colspan="5" | Conjoined
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| |-
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| | Links only work with currently enrolled UNSW students. |
| |} | | |} |
| | ==Archive== |
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| Table based upon recent Twinning Review.<ref><pubmed>12957099</pubmed></ref>
| | * 2014 [[Media:ANAT2341 Lecture 3 - 2014 Week 1 and 2 Development.pdf|2014 Lecture 3 PDF]] |
| | | * 2013 - A PDF of the lecture powerpoint show can be found here: [[File:ANAT2341_Lecture_2_-_Beverdam_-_Week_1_and_2.pdf]] Lecture Date: 6 August 2013 Lecture Time: 16:00 Venue: Biomedical Theatre E Speaker: Annemiek Beverdam |
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| :Links: [[Abnormal_Development_-_Twinning| Twinning]] | [http://www.twins.org.au/index.php?page=31 Australian Twin Registry]
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| ==Week 1 Human Development Overview==
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| [[Image:Week1_summary.jpg|400|Week 1 Human Development Overview]]
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| ===Genome Expression===
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| The following figure is from a recent study<ref name="PMID20890283"><pubmed>20890283</pubmed>| [http://www.nature.com/nbt/journal/vaop/ncurrent/full/nbt.1686.html Nat Biotechnol.]</ref> using video and genetic analysis of ''in vitro'' human development during week 1 following fertilization.
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| [[File:Model human blastocyst development.jpg|600px]]
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| * EGA - embryonic genome activation | |
| * ESSP - embryonic stage–specific pattern, four unique embryonic stage–specific patterns (1-4)
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| :'''Links:''' [[:File:Model human blastocyst development.jpg|Figure with legend]] | [[Quicktime_Movie_-_Blastocyst_Development|Blastocyst Quicktime Movie]] | [[Movie_-_Blastocyst_Development|Blastocyst Flash Movie]]
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| ==Images==
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| <gallery>
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| File:Stage1_size_with_ruler.jpg|Stage1_size_with_ruler
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| File:Human-oocyte_to_blastocyst.jpg|Human-oocyte to blastocyst
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| File:Human embryo day 2.jpg|Human embryo day 2
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| File:Human embryo day 3.jpg|Human embryo day 3
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| File:Human embryo day 5.jpg|Human embryo day 5
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| File:Human_carnegie_stage_3_label.jpg|Human carnegie stage 3
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| </gallery>
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| ==Movies==
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| {| border='0px'
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| | {| class="wikitable" |
| | ! ECHO360 Recording |
| |- | | |- |
| | [[File:Follicle 001 icon.jpg|90px|link=Development_Animation_-_Ovulation]] | | | [[File:ECHO360_icon.gif|right|link=https://lectures.unsw.edu.au/ess/portal/section/691ba9a0-7c35-4ad2-8fd0-846db7771557]] |
| | [[File:Fertilization 002 icon.jpg|90px|link=Development_Animation_-_Fertilization]]
| | [[Lecture_-_Fertilization|Lecture 3]] - [https://lectures.unsw.edu.au/ess/echo/presentation/ac5dccd1-f9dc-413f-ad5b-a6eadf45f9b8 Rich Media Playback] | [https://lectures.unsw.edu.au/ess/echo/presentation/ac5dccd1-f9dc-413f-ad5b-a6eadf45f9b8/media.m4v Vodcast Playback] | [https://lectures.unsw.edu.au/ess/echo/presentation/ac5dccd1-f9dc-413f-ad5b-a6eadf45f9b8/media.mp3 Podcast Playback] |
| | [[File:Pronuclear_fusion 001 icon.jpg|90px|link=Development_Animation_-_Pronuclear_Fusion]]
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| | [[File:Week1 001 icon.jpg|90px|link=Development_Animation_-_Week_1]] | |
| |-
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| | [[Development_Animation_-_Ovulation|Ovulation]]
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| | [[Development_Animation_-_Fertilization|Fertilization]] | |
| | [[Development_Animation_-_Pronuclear_Fusion|Pronuclear Fusion]]
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| | [[Development_Animation_-_Week_1|Week 1]]
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| |-
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| |}
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| {|
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| | width= 200px | [[File:Human-blastocyst-day-3-6-icon.jpg|120px|link=Quicktime_Movie_-_Blastocyst_Development]]
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| | width= 200px | [[File:Human_blastocyst_day_5-6.jpg|120px|link=Quicktime_Movie_-_Blastocyst_Contractions]]
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| | width= 200px | [[File:Human blastocyst hatching movie icon.jpg|120px|link=Quicktime_Movie - Blastocyst Hatching]]
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| |-bgcolor="FAF5FF"
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| | [[Quicktime_Movie_-_Blastocyst_Development|Blastocyst Development]]
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| Early development day 3 to 6
| | Links only work with currently enrolled UNSW students. |
| | [[Quicktime_Movie_-_Blastocyst_Contractions|Blastocyst Contractions]]
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| (day 5 to 6)
| | * [http://lectopia.telt.unsw.edu.au/lectopia/lectopia.lasso?ut=153&id=140230 2012 Lecture 3 - Week 1 and 2 Development] |
| | [[Quicktime_Movie_-_Blastocyst_Hatching|Blastocyst Hatching]]
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| (day 5 to 6)
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| |} | | |} |
|
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| == Glossary Links ==
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|
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| [[A|A]] | [[B|B]] | [[C|C]] | [[D|D]] | [[E|E]] | [[F|F]] | [[G|G]] | [[H|H]] | [[I|I]] | [[J|J]] | [[K|K]] | [[L|L]] | [[M|M]] | [[N|N]] | [[O|O]] | [[P|P]] | [[Q|Q]] | [[R|R]] | [[S|S]] | [[T|T]] | [[U|U]] | [[V|V]] | [[W|W]] | [[X|X]] | [[Y|Y]] | [[Z|Z]] | [[Numbers|Numbers]]
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|
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| == References ==
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| <references/>
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| ===Textbooks===
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| * '''The Developing Human: Clinically Oriented Embryology''' (8th Edition) by Keith L. Moore and T.V.N Persaud - Chapter 2
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| * '''Larsen’s Human Embryology''' by GC. Schoenwolf, SB. Bleyl, PR. Brauer and PH. Francis-West - Chapter 2
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|
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| ===Online Textbooks===
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| * '''Developmental Biology''' by Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000 [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=dbio.figgrp.2615 Figure 11.22. The cleavage of a single mouse embryo in vitro] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=dbio.figgrp.2618 Figure 11.25. Mouse blastocyst hatching from the zona pellucida] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=implantation&rid=dbio.figgrp.2612 Figure 11.20. Development of a human embryo from fertilization to implantation] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=blastocyst&rid=dbio.figgrp.2617 Figure 11.24. Implantation of the mammalian blastocyst into the uterus]
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| * '''Molecular Biology of the Cell''' 4th ed. Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter New York and London: Garland Science; c2002 - [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=mboc4.section.3738 Fertilization] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=mboc4.figgrp.3955 Figure 21-84. Scanning electron micrographs of the early mouse embryo] | [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=mboc4.figgrp.3927 Figure 21-69. The blastula]
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| * '''Molecular Cell Biology''' by Lodish, Harvey; Berk, Arnold; Zipursky, S. Lawrence; Matsudaira, Paul; Baltimore, David; Darnell, James E. New York: W. H. Freeman & Co.; c1999 Chapter 13. Regulation of the Eukaryotic Cell Cycle
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| * '''The Cell - A Molecular Approach''' by Cooper, Geoffrey M. Sunderland (MA): Sinauer Associates, Inc.; c2000 [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=cooper.figgrp.2492 Figure 14.37. Meiosis of vertebrate oocytes]
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| * '''HSTAT''' - [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=hstat6.section.1395#1396 In Vitro Fertilization As A Medical Treatment For Male or Female Infertility]
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| * '''Human Molecular Genetics 2''' Strachan, Tom and Read, Andrew P. New York and London: Garland Science; c1999 [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=morula&rid=hmg.figgrp.928 Figure 8.19. Changes in DNA methylation during mammalian development]
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| ===Search ===
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| * '''Bookshelf''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=blastocyst blastocyst] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=morula morula] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=implantation implantation] | [http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books&cmd=search&term=ectopic_pregnancy ectopic pregnancy]
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| * '''Pubmed''' [http://www.ncbi.nlm.nih.gov/sites/gquery?itool=toolbar&cmd=search&term=blastocyst blastocyst] | [http://www.ncbi.nlm.nih.gov/sites/gquery?itool=toolbar&cmd=search&term=implantation implantation] | [http://www.ncbi.nlm.nih.gov/sites/gquery?itool=toolbar&cmd=search&term=ectopic_pregnancy ectopic pregnancy] |
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| {{Template:2011ANAT2341}}
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