Human Embryology Test 2 - Doroski

implantation

embedding of embryo in the uterine lining, embryo completely sinks in, uterine cells cover embryo, placenta develops

placenta

exchange organ between maternal and fetal circulation

components of placenta

chorion, decidua

chorion

fetal part of placenta

components of chorion

forms from trophoblast, chorionic villi

chorionic villi

extensions of chorion, where exchanges occur between fetal and maternal blood

decidua

maternal part of placenta

components of decidua

forms from the endometrium, decidual reaction

decidual reaction

endometrial changes due to implantation, provides and area safe from mother's immune system

function of placenta (O2 & nutrient exchange)

travels from maternal blood to fetal blood, umbilical cord receives O2 & nutrients

function of placenta (CO2 & waste exchange)

travels from fetal blood to maternal blood, umbilical cord is emptied of wastes/CO2

antibody

protective proteins made by immune system

antibody exchange (placenta)

maternal antibodies cross placenta, protect fetus

what is a problem with the placenta being a (very permeable) exchange organ?

alcohol causes fetal alcohol syndrome, can cause crack/cocaine addictions,
some infectious agents could cross and harm embryo/fetus

human chorionic gonadotropin (HCG)

hormone produced by developing placenta (detected in pregnancy tests)

what is the embryo doing at the point when it is detected in pregnancy tests?

implanting itself in uterine wall

when do medical dictionaries say pregnancy and conception begin?

most common: pregnancy begins at fertilization, conception occurs at fertilization, less common: implantation in womb

ectopic pregnancy

an implantation in an abnormal area (most common in uterine tubes)

issues with ectopic pregnancy

growth of embryo can cause uterine tube to burst (resulting blood loss can be fatal)

basic cause of ectopic pregnancy

slowed transport, ZP normally prevents attachment, premature hatching promotes implantation

causes of slowed transport

cilia problems, sexually transmitted diseases, endometriosis

cilia problems (slowed transport)

hatching may occur before transport is complete, smoking slows cilia, increased age can lower number of cilia

sexually transmitted diseases (slowed transport)

gonorrhea & chlamydia, can scar uterine tubes, creates obstacles in uterine tubes

endometriosis (slowed transport)

endometrium-like tissue in abnormal areas, can promote uterine tube scarring, provides abnormal areas of easy implantation

ectopic pregnancy treatments

expectant management, salpingectomy, salpingostomy, methotrexate, embryo transfer

expectant management

close observation with interventions only when symptoms manifest

salpingectomy

removal of uterine tube containing embryo

principle of double effect

if doing something morally good has a morally bad side effect, it's ethically permissible so long as the bad effect was unintended

salpingostomy

removal of embryo, leaving uterine tube intact

methotrexate

a drug that prevents cell division and growth

embryo transfer

transfer of embryo to womb (successfully completed in 1915 & 1980)

regulative development

ability to produce normal structures if cells are removed/added

blastomere isolation (regulative development)

single blastomeres can form normal embryos, up to 4-cell stage

regulation decreases as...

development progresses

does fetal surgery result in scars?

no, fetal children and young children heal faster and more completely than adults

chimera

an organism with a mixture of cells from two individuals

what is an example of a chimera?

adding a blastomere to a blastocyst; blastomere integrates with the host blastocyst

tetraparental embryo

embryo with 4 genetic parents

tetraparental embryo (scenarios)

blastomeres of 2 early embryos are mixed, a single embryo forms, a normal organism can occur

fetal microchimerism

the presence of fetal cells in mother's body; found in multiple organs, may protect from diseases

fertility/menstrual cycle

the cycle of physiological preparations for a possible pregnancy

fertility cycle functions

produces oocytes, conserves energy, protects from pathogens

fertility cycle effects

short-term partner preferences change throughout cycle (long-term preferences do not change), fluctuations in attraction to partner, stronger preferences for symmetrical male scents mid-cycle

what is the average cycle length?

28 days (most aren't 28 days though)

preovulatory phase

menstruation to ovulation (can be variable); ovulation cannot be predicted based off menstruation

postovulatory phase

ovulation and menstruation (relatively constant); menstruation can be predicted based of ovulation

standard fertility phases

menstrual phase, proliferative phase, secretory phase

menstrual phase

bleeding occurs (indicates day 1 of cycle), surface layer of endometrium is lost, deep layer remains

menarche

the onset of menstruation

menopause

cessation of menstruation

what causes menopause?

lack of follicles, estrogen decreases

proliferative phase

follicle stimulating hormone (FSH) peaks shortly before ovulation (stimulates follicle development), estrogen levels rise, luteinizing hormone (LH) surge occurs

what happens when estrogen levels rise during the proliferative phase?

estrogen is produced by cells of the mature follicle, increases sensitivity to progesterone, thickens endometrium (aid implantation), promotes cili growth in uterine tube, creates cervical mucus (E mucus)

LH surge

peak in LH that causes ovulation, causes follicle to become corpus luteum

corpus luteum

follicle cells left in ovary after ovulation

secretory phase

ovulation occurs, progesterone rises

what happens when ovulation occurs during the secretory phase?

corpus luteum is created, corpus luteum produces estrogen & progesterone

what happens when progesterone rises during the secretory phase?

thickens cervical mucus (prevents pathogen & sperm penetration), promotes nutrient secretion in uterine tubes for possible conceptus

what does progesterone do?

prevents new follicle development (blocks FSH & LH), increases body temperature

is pregnancy a phase of the fertility cycle?

no, interrupts the fertility cycle and new hormonal patterns develop

HCG (human chorionic gonadotropin) during pregnancy

maintains corpus luteum (produces estrogen/progesterone. progesterone prevents menstruation)

estrogens during pregnancy

produced by placenta, rises throughout pregnancy, increases muscle tissue (needed to push baby out & allows uterus to grow as baby grows)

progesterone during pregnancy

produced by placenta, rises throughout pregnancy, prevents uterine contractions (prevents premature birth, helps maintain pregnancy)

infertility

the inability to achieve pregnancy after 1 year of normal relations (a couple with no pathology could be defined as infertile)

male causes of infertility

sperm problems, blockage of ducts

sperm problems

low sperm count, poor sperm movement, odd sperm shape

blockage of ducts

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 cervical mucus, prevent endometrial development), high levels of fertility suppressing hormones

reproductive blockages

thick cervical mucus, scarring in uterine tubes

why are most reproductive technologies against Church teachings?

separates the unitive and procreative, treats children as a product, replaces the marital act as the proper place for reproduction

church teachings rule of thumbs

procedures that help conjugal union to achieve procreation is moral, procedures that add a 3rd party are immoral, procedures using a lab procedure to replace intercourse are immoral

reproductive technologies

seminal evaluations, ovulation induction, intrauterine insemination (IUI)

seminal evaluations

testing of qualities of semen

ovulation induction

a chemical is used to stimulate ovulation

intrauterine insemination (IUI)

introduction of semen into female's uterus

seminal evaluation components

used to evaluate shape, number, and movement of sperm; evaluates seminal fluid; licit if semen is obtained through marital act (using perforated condom), illicit if semen is obtained through masturbation

ovulation induction components

can be licit, illicit if used to donate oocytes to another couple

IUI components (morality)

illicit if husband's sperm is not used or obtained through masturbation, morality is unclear if semen is licitly obtained

IUI components (effectiveness)

more effective when donor (not husband's is used), has been used to impregnate lesbians and single women, success rate is double to that of normal intercourse, rate of twins is similar to normal intercourse

IUI with ovulation induction

increases IUI success rate, increases rate of twins (more dangerous, seen as negative outcome)

ART

Artificial (Assisted) Reproductive Technology

in vitro fertilization (IVF)

test tube babies, intrinsically illicit

steps of IVF (6 steps)

stimulation of oocyte production, removal of multiple oocytes, collection of sperm, combining sperm and oocytes, embryo preservation, embryo transfer

1) stimulation of oocyte production

multiple oocytes are stimulated to develop

2.) removal of multiple oocytes

ovulation is suppressed and oocytes are removed

3.) collection of sperm

usually occurs through masturbation, sperm can be stored, frozen for years, sperm are washed and capacitated

why are sperm washed & capacitated?

seminal fluid is washed away (so it cannot prevent capacitation), washing decreases number of abnormal sperm, may remove infectious agents

4.) combining sperm and oocytes

sperm may be deposited. in general area of oocytes, ICSI, sperm do not need to move much, many oocytes are fertilized at one time

intracyoplasmic sperm injection (ICSI)

injection of sperm into an oocyte

sperm do not need to move much

fertilization with abnormal sperm is more likely because journey to oocyte normally weeds out poor sperm

5.) embryo preservation

embryos develop until about 8-cell stage, "best" embryos chosen for use, "excess" embryos frozen in liquid nitrogen (used for future IVF cycles), PSD

preimplantation genetic diagnosis (PSD)

removal of blastomere for genetic testing

components of PSD

sometimes used to evaluate embryos, increases embryo death risk

why is PSD used to evaluate embryos?

removed cells are tested for favorable characteristics, desired embryos are implanted, other embryos are frozen/destroyed

embryo transfer (def)

movement of embryos to the uterine cavity

6.) embryo transfer

one embryo will implant in uterus with successful IVF, surrogacy

surrogacy

embryo transfer to a woman who did not contribute gametes

gamete intrafallopian transfer (GIFT)

introduction of a sperm and oocyte into Fallopian tubes

zygote intrafallopian transfer (ZIFT)

introduction of a zygote to the fallopian tube