human embryo genesis

8/6/2019 Human Embryo Genesis

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PRE-EMBRYONIC DEVELOPMENT



HUMAN DEVELOPMENT IN THE WOMB

1.1.BILAMINAR GERMBILAMINAR GERMDISC (2DISC (2ndnd Week of Week of Development)Development)

2.2.TRILAMINAR GERMTRILAMINAR GERM

DISC (3DISC (3rdrd Week of Week of Development)Development)

3.3.EMBRYONICEMBRYONICPERIOD (3PERIOD (3rdrd to 8to 8thth

Week of Week of Development)Development)

4.4.FETAL PERIOD (3FETAL PERIOD (3rdrd

Month to Birth)Month to Birth)



Gastrulation takes place in the 2nd week after

fertilization. The primitive streak can be seen on the surface of

the embryo, and the 3 germ layers (ectoderm,mesoderm, and endoderm) are differentiated.



3rd week: neurulation occurs, appearance of the 1st somites,

which give rise to the muscles, vertebrae, and CT.Spontaneous abortions due to major chromosomalabnormalities usually occur at this time.

4th week: organogenesis begins. Embryo is about 2 mm long. 5th week: Head enlarges; eyes, ears and nose become

prominent.



The fetus has grown to about 3 inches (8cm) long; weight approximately1 ounce (25 grams). Bone is beginning to replace cartilage and the ribs

are appearing; nose and chin are well defined; movements can bemeasured. The child will begin to suck its thumb, open and close its

mouth. The external genitalia are almost defined.



Fetal movement canbe felt by the mother.

Fetus is in fetal

position. Eyelids are fully open. Fetus sizehas increased to ~12

inches and ~3pounds.

The 2nd & 3rd

trimesters arecharacterized byrapid growth and

development required for theviability of thebaby after its

birth.



DEVELOPMENTAL EVENTS OF THE FETAL PERIOD



Anatomical Changes The female reproductive organs and breasts become increasingly vascular and

engorged with blood. The uterus enlarges dramatically, causing a shift in the woman·s center of gravity

and an accentuated lumbar curvature (lordosis). Placental production of the hormone relaxin causes pelvic ligaments and the pubic

symphysis to soften and relax. There is a normal weight gain of around 28 pounds, due to growth of the fetus,

maternal reproductive organs, and breasts, and increased blood volume.

THE PREGNANT MOTHER



DELIVERY

True labor is characterized by uterine contractionthat occur every 15-20 minutes and last for at least 40 seconds

There are 3 stages:1st : Effacement occurs in which the cervical canal

slowly disappears and the babies head acts as awedge to cause cervical dilation

2nd: Uterine contractions every 1-2 minutes lasting for ~1 minute each; an incision is made to theopening to help the baby as its head reaches theexterior; once the baby is born the umbilical cordis cut and tied

3rd: The afterbirth is delivered usually about 15minutes after the birth of the baby



Rising levels of placental estrogens,progesterone, and lactogen stimulatethe hypothalamus to produceprolactin-releasing hormone (PRH),which promotes secretion of prolactinby the anterior pituitary.

Colostrum, a high-protein, low-fat product is initially secreted by themammary glands, but after two tothree days, true milk is produced.

Nipple stimulation during nursingsends neural signals to the

hypothalamus, resulting in productionof PRH and a burst of prolactin that stimulates milk production for thenext feeding.

Oxytocin causes the let-down reflex,resulting in the release of milk fromthe alveoli of the mammary glands inboth breasts.

Advantages of breast milk are: betterabsorption and more efficient metabolism of many components;antibodies and other chemicals that protect the infant; a natural laxativeeffect that helps to prevent physiological jaundice; andencouragement of the natural

intestinal fauna.



The chance of twin sharing of amnion andchorion depends upon when the splitting of

the blastomeres occurred.



ASSISTED REPRODUCTIVETECHNOLOGY (IVF/ICSI)

Volunteer female is given heavydoses of gonadotropic hormonesto cause ripening of ovarian

follicles which are aspirated frombody cavity.

FSH and LH added to 3-4explanted follicles cause in vitrooocyte maturation; eggs are then

fertilized, and re-introduced intoa receptive uterus.

Donor eggs, sperm and embryosmaybe kept frozen indefinitely.

Possibilities exist for genemanipulation before implantation

(designer babies?)



Obtaining eggs by aspiration, assisted bylaparoscopic or ultrasound visualization techniques



Storing gametes by freezing in liquid nitrogen Performing in-vitro fertilization (IVF) and culture of

embryos: adding concentrated capacitated sperms to eggs Microinjection into perivitelline space, or direct injection

into oocyte; embryos are then allowed to develop to 2-8 cellstages in culture; preserving the embryos withcryoprotectants at ²1000C; transferring the embryo to themother via catheter introduction into cervix

Other techniques used: (GIFT), the transfer of gametesdirectly into the fallopian tube; and ZIFT, the transfer of zygotes into the fallopian tube.



1.THE PERFECT EMBRYO EMPORIUM: Our motto is "We test

every one of our embryos for all 433 currently known geneticdiseases. With us, YOU KNOW WHAT YOU'RE GETTING!"

2."Are you a healthy young woman who wants to make $5,000 for that new car, new outfit or to pay off your college loans? If your heredity qualifies you, your eggs or embryo may be

worth BIG BUCKS! Give us a call at "Embryos 'R Us" at 555-BABY. Special offer: $50,000 for an egg from a tall femalewith a 1400 or better CSAT score.

3.Well dressed smiling woman ordering an embryo: "I'll take awhite, male embryo. Put it on my Credit card please. Deliver it

to the 'Happy Mom' Implantation Clinic next Monday at 9 AM.4.Are your genes too great to DIE? Does the world need morepeople like YOU? Is there just not enough of you to goaround? Give us a call at CLONE WORLD, at 800-EGO-TRIP.We'll take care of it all; the cloning and surrogates. Ask about our discount deal on 5 or more "fantastic me" clones.



5.For those of you whose genes are just TOO FANTASTIC forthe world to lose? Visit CLONE WORLD!

6."Are you and your husband too busy to have a baby? Are your

jobs too demanding and too important to give you time off tobecome the great Mom & Pop you know you can be? If so, visit us at SURROGATE RENT-A-WOMB INC; we guarantee a 1st

class womb for your little angel. Our wombs are all betweenthe optimal bearing years of 20 to 25." Our motto: "You

Provide the EMBRYO and We Provide the Womb Worthy of your Little Prince or Princess". We also test your ownembryos for genetic defects before implantation to insure that you have the HEALTHY child every person deserves. Inquiretoday about our "Defect-Free Embryo Plan".

7."ANNOUNCING OUR FALL SALE OF DISCOUNT EMBRYOSAND EGGS. WE'RE CLEARING OUR INVENTORY TO GETREADY FOR THE NEW MODELS. 50% PERCENT OFF WHITEFEMALE EMBRYOS; MANY OTHER BARGAINS. We needspace for the new summer line of Leonardo DiCaprio embryos(with this one we're going to "sink" the competition)."



TERATOGENIC SUSCEPTIBILITY OF HUMAN EMBRYO



http://ublib.buffalo.edu/libraries/projects/cases/genetics/genetic _selection.pdf .

http://simbryo.stanford.edu/previewearly.html

http://www.bioscience.org/atlases/fert/fetus.htm

http://embryology.med.unsw.edu.au/Movies/Movies.htm

http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000138&ptid=17

C:\Users\ofelia\Documents\YouTube Downloader\MedicalAnimation% Birth of Baby (Vaginal Childbirth).avi

C:\Users\ofelia\Documents\YouTube Downloader\3D animationof how IVF works.avi