Human Embryology test #2 Doroski pt. 2

clinical definition of infertility

inability to achieve a pregnancy after 1 year of normal relations (nothing is done to avoid pregnancy)

Male causes of infertility

sperms problems and blockage of ducts

sperm problems

low sperm count

- counts have decreased since the 1930s

- likely due to increases in environmental estrogens

poor sperm movement

odd sperm shape

blockage of ducts (male)

may prevent sperm transport

may prevent addition of seminal fluid

Female causes of infertility

-hormonal disorders

-reproductive blockages

Hormonal disorders

low hormone levels

-prevent ovulation

-only create infertile cervical mucus

-prevent endometrial development

high levels of fertility suppressing hormones

reproductive blockages

-thick cervical mucus

-scarring in uterine tubes

seminal evaluation

testing of qualities of semen

used to evaluate number/shape/ movement of sperm

evaluate seminal fluid

ovulation induction

chemical used to stimulate ovulation

Intrauterine insemination (IUI)

introduction of semen into female's uterus,

success rate is double normal intercourse

rate of twins is similar to normal intercourse

Assisted reproductive technology (ART)

includes all fertility treatments in which both egg and sperm are handled, also known as artificial reproductive technologies

Invitro Fertilization (IVF)

artificial reproductive technology

steps:

-stimulation of oocyte production

-removal of multiple oocytes

-collection of sperm

-combining sperm and oocytes

-embryo preservation

-embryo transfer

stimulation of oocyte production

multiple oocytes are stimulated to develop

removal of multiple oocytes

-ovulation is suppressed

-oocytes are removed

collection of sperm

-usually occurs through masturbation

- sperm (and oocytes) can be stored and frozen for multiple years

-sperm are "washed" and capacitated

sperm washing

-seminal fluid is washed away (seminal fluid contains factors that prevent capacitation)

-washing decreases number of abnormal sperm

-may remove infectious agents

combining sperm and oocytes

sperm may be deposited in the general area of the oocytes; sperm don't need to move much; fertilization with abnormal sperm is more likely; journey to oocyte normally "weeds out" poor sperm; many oocytes are fertilized at one time

intracytoplasmic sperm injection (ICSI)

injection of sperm into oocyte

embryo preservation

-embryos develop until ~8-cell stage

-the "best" embryos are chosen for use

-"Excess" embryos are frozen in liquid nitrogen

-Frozen embryos are used for future IVF cycles

Preimplantation Genetic Diagnosis (PGD)

removal of blastomere for genetic testing

-removed cells are tested for favorable characteristics

-desired embryos are implanted

-other embryos are implanted or destroyed

embryo transfer

movement of embryos into uterine cavity

-if IVF is successful one embryo will implant in the uterus

surogacy

embryo transfer to a woman who did not contribute gametes

Gamete intrafallopian transfer (GIFT)

introduction of sperm and oocyte into fallopian tubes

Zygote intrafallopian transfer (ZIFT)

introduction of zygote into the uterine tube

-zygote is created using IVF

-zygote is transferred without testing to find the "best" zygote

ART success rates

-only as or less successful than treatments that are over 30 years old (ex. tubal factors, endometriosis, or polycystic ovaries)

-implantation (embryo transfer) is ≈ 35% successful

Why are multiple embryos often created and transferred in IVF?

Multiple embryos are often created and transferred due to low success rates. Multiple embryos increases chances of success (but also leads to greater multiples).

ART risks and complications

-increases chance of multiples

-can cause ovarian hyperstimulation syndrome (OHSS)

-increases preeclampsia (high blood pressure in pregnancy)

-increases risk of birth defects

-increases risk of ectopic pregnancy

-does not reveal the reason for infertility

-does not technically treat infertility