Endo/Repro Exam 2: Physiology- Pregnancy (Dr. Leavis)

after ovulation the oocyte still has attached granulosa cells, now called the ________

corona radiata

what causes the ovulated oocyte to enter the fallopian tube?

the beating of the cilia along the fimbriae

the highest probability of successful fertilization is within the first ___ hours

12

Lifetime of ovulated oocyte is about 24 hours but highest probability of successful fertilization is within the first 12 so that fertilization typically occurs in the outer third of the fallopian tube and the newly formed ___________ (fertilized oocyte) proceeds towards the uterus.

zygote

sperm approaches oocyte and releases its acrosomal enzymes, _______, to break through the corona radiata

acrosin

What digests the zona pellucida and penetrates the oocyte?

Hydrolytic enzymes (e.g. hyaluronidase)

What allows sperm to attach to receptors on the oocyte's plasma membrane?

acrosomal reaction

what triggers the cortical granular reaction?

sperm head entering the oocyte

the cortical granular reaction is a __________ dependent reaction that alters the surface glycoprotein in the zona pelucida to prevent entry of other sperm.

Ca++

the ______________ is a Ca++ dependent reaction that alters the surface glycoprotein in the zona pelucida to prevent entry of other sperm.

cortical granular reaction

Once inside the oocyte, the sperm head swells to become the _________, which fuses with oocyte to develop a diploid zygote containing a full complement of 46 chromosomes.

male pronuclus

T/F: The zygote will begin to divide even as it is transported down the fallopian tube toward the uterus.

True

when does the oocyte complete its second meiotic division?

once fertilized

type of twins produced when the zygote splits into two cells in the first division, each will grown into an individual:

monozygotic (identical) twins

type of twins produced when two follicles develop and are fertilized separately:

dizygotic or fraternal twins

The zygote takes how many days to reach the uterus?

3-4

the zygote takes 3-4 days to reach the uterus by which time it has repeatedly divided to reach the ___________ stage (~16 cells)

morula

by day 6 - the zygote will have become a ___________, containing an outer layer of trophoblastic cells and an inner cell mass.

blastocyst

movement down the fallopian tube occurs by (2)

- Beating of cilia

- Muscle contractions

(Cilia also secrete nutrient materials)

when implantation finally occurs, what will the zygote have become?

blastocyst

What has the following characteristics:

- Thin layer of cells that surround the blastocoel, a fluid filled cavity

- It will participate in implantation and will contribute the embryonic component of the placenta

- It will produce the hormone hCG and provide nutrition to the embryo

trophoblast

What cells become the fetus?

embryoblast

the developing blastocyst will float freely in the uterus for up to ______ days before implantation

3

Before implantation proper, the blastocyst secretes enzymes that degrade the zona pellucid, a process called what?

hatching

hatching is done by the blastocyst prior to implantation to degrade the _______

zona pellucid

implantation occurs in 3 steps:

- Apposition

- Adhesion

- Invasion

What step of implantation?

When the embryo approaches the site where it will implant, and both embryo and endometrium secrete a variety of cytokines that prepare for implantation

apposition

What step of implantation?

When the trophoblastic cells adhere to the endometrial surface via integrins, proteins that bind to sites on both membranes and link them together

adhesion

adhesion is when the trophoblastic cells adhere to the endometrial surface via ________ , proteins that bind to sites on both membranes and link them together

integrins

What step of implantation?

When the trophoblast cells rapidly proliferate and form the syncytiotrophoblast, a multinucleated mass of cells that invade the endometrium and extend finger-like projections into the uterine tissue which is degraded by lytic enzymes secreted by them.

invasion

By what days has the blastocyst penetrated the uterine wall and completely implanted?

8-12

a multinucleated mass of cells that invade the endometrium and extend finger-like projections into the uterine tissue which is degraded by lytic enzymes secreted by them:

syncytiotrophoblasts

During invasion, the other type of trophoblast cells are the inner ___________ which support the embryonic cells.

cytotrophoblasts

What cells produce hCG (human chorionic gonadotropin)?

syncytiotrophoblasts

What can be detected in the urine of a pregnant woman 6-12 days after ovulation?

hCG (human chorionic gonadotropin)

What binds to the LH receptors on the corpus luteum, allowing it to continue secretion of estrogen and progesterone needed to maintain the endometrial wall & preventing its regression?

hCG

By the end of the first trimester, what replaces hCG to produce necessary amounts of progesterone and estrogen to maintain pregnancy?

placenta

the placenta also secretes the hormone ________, which, along with prolactin, helps to prepare the breast for lactation

human placental lactogen

which pregnancy hormone predominates at the beginning of pregnancy to ensure relaxation of uterine smooth muscles?

progesterone

besides progesterone, the placenta will produce ___________ to ensure relaxation of uterine smooth muscles

relaxin

which pregnancy hormone increases the irritability of the uterine smooth muscle and the stretch that occurs with the growth of the fetus in late pregnancy initiates contractions that gradually grow in frequency and intensity?

estrogen

during parturition, stretching of the cervix induces release of __________ which, by increasing the intensity of uterine contractions, increases the cervical stretching

oxytocin