Assisted Reproductive Technologies (ART)
Assisted Reproductive Technologies (ART)
* Artificial Inseminations
* In vitro fertilization (IVF)
* Embryo transfers
* “Cloning”
Some Common Reasons for ART
* Infertility
o Male
o Female
* Absence of one or the other partner
o Lesbian, gay, transgendered parent
o Death of spouse
* Genetic Engineering
o Hereditary disorders
o Sex selection
Artificial Insemination
* Method other than intercourse to facilitate fertilization
* Introduction of semen or washed sperm into the vagina, the uterus or the Fallopian tubes
* Can be from legally recognized partner (husband) = AIH, or from another donor = AID
* Fresh or frozen semen samples (e.g., Select Sires, Inc.)
Long History of AI
* Agricultural uses
o 14th Century breeding of Arabian horses
o 1780 Spallanzani used sperm in dog breeding
o By 1940 many breeders Coops
* Human experience
o John Hunter (1780s) patient with hypospadias
o Marion Sims (mid 1800s) one success out of 55 tries
o By 1941 over 10,000 births in the US by AI
o By 1955 over 50,000
o Now, approx 1 percent of all births in US
The Famous Turkey Baster
Sorting sperm according to sex
* Sperm are sexually dimorphic: half have an X-chromosome, half have a Y-chromosome
* The X-chromosome is much bigger, so “female determining” sperm have more DNA, and are (hypothetically) slightly heavier
* Try to physically separate sperm based on size or DNA content
* Mark either the X or Y chromosome in some way and sort on the basis of the marking.
More than one X chromosome: Sex chromatin (
Flow sorting of marked sperm
IVF: In vitro fertilization
* Surgically remove “ripe” egg from follicle in ovary
* Obtain sperm sample
* Mix egg and sperm in glass (in vitro) dish
* Allow fertilized egg to develop for several days (in nutrient solution at body temp)
* Put embryo(s) (blastocyst) into “prepared” uterus (or Fallopian tube)
* Variation: sperm and egg are put into Fallopian tube
Fertilized egg or “zygote” [note the two nuclei, egg and sperm]
Direct injection of sperm into egg
3 day old human embryo
Embryo Transfers
* One kind of ART
* First Step: IVF
* Transfer Embryo into Recipient
* Combinations of:
o Egg Donor
o Sperm Donor
o Recipient
Outcomes of ART Pregnancies
One-third of ART deliveries are multiple births
Multiple Embryo Transfer
Success rate goes down with age
Births depend on age of eggs not mom
Three Thawed Embryos
Bring on the Clones
Clones in Context
* A clone is any organism whose genetic information is identical to that of a "mother organism" from which it was created.
* A clone is an exact replica of all or part of a macromolecule (e.g. DNA).
* A clone is a computer system based on another company's system and designed to be compatible with it.
* A clone is a butch or masculine gay man, a term mostly associated with the 70s and 80s. The "clone uniform" is mustache, jeans, and white t-shirt. E.g., a “Chelsea Clone” etc….
Reproductive vs Non-reproductive Cloning
Gestational Cloning
* New technology: becoming widely used in animal reproduction
* Allows unlimited reproduction of genetically identical individuals (clones)
* Potential for a sort of “genetic immortality”
* Many possible “good” and “bad” applications
* Societal vs Individual Rights: very unclear
Clones in Context
* Any group of cells that descends from a single cell….
o Includes such groups of cells as freckles, colonies of mold on bread, antibody producing lymphocytes, tumor cells…
* Any organism grown up from a single cell…
o Includes some plants, identical twins, some animals such as “Dolly” the Sheep…
Assisted Reproductive Technologies (ART).ppt
0 comments:
Post a Comment