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GIGU - Week 5/6 (STILL QUARANTINE) > 36- Fertilization & Implantation > Flashcards

36- Fertilization & Implantation Flashcards

1
Q

This occurs at about day 15-16 of the menstrual cycle. It allows for recombination of genetic material and is the initiation of events that begin embryonic development.

A

Fertilization

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2
Q

Both sperm and oocyte must travel to the _________ of the oviduct for fertilization to occur.

A

Ampulla

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3
Q

A surge in _______ leads to follicular rupture, and the ovum and surrounding corona radiata are ejected into the peritoneum. Oocyte is swept into oviduct by ________.

A

LH

Fimbriae

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4
Q

About 300 million sperm enter the vagina near the uterus, and about 200 million reach the ampulla of the oviduct (many barriers to overcome). __________ contractions as a result of increased estrogen near ovulation period help to move sperm through the cervix/uterus.

A

Myometrium

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5
Q

Incapacitated sperm bind actively to the epithelial cells of the oviductal ________. They become unbound when they are capacitated.

A

Isthmus

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6
Q

Sperm binding to the oviductal isthmus slows the _________ process, extends the sperm lifespan (several days), and increases the probability the sperm will be in the oviduct when the egg is ovulated.

A

Capacitation

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7
Q

The __________ of sperm is associated with sperm capacitation and chemical signals from the oocyte. It involves a change in flagella motion from wave-like to whip-like. It is necessary for the sperm to detach from the epithelium of the oviduct and increases mobility. Helps propel sperm through outer layers of egg to reach plasma membrane.

A

Hyperactivation

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8
Q

In sperm capacitation, the plasma membrane of epididymal spermatozoa contains a complement of surface molecules (proteins and carbohydrates). These surface molecules in epididymal sperm become coated with _______ ______ ______ that mask portions of the membrane molecules.

A

Seminal Plasma Proteins

***This is during ejaculation!

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9
Q

When sperm are exposed to the female tract environment, these seminal plasma coatings, along with some of the surface molecules, are removed thus exposing portions of the molecules that can bind to the _______ _______ of the oocyte. This process is called _________.

A

Zona Pellucida

Capacitation

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10
Q

Fertilization is a multi-step process whereby multiple sperm bind the ________ _______, but only one sperm fertilizes the egg.

A

Corona Radiata

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11
Q

For fertilization, 3 barriers must be breached which are…

A
    • Corona Radiata (expanded cumulus)
    • Zona Pellucida
    • Plasma membrane of oocyte
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12
Q

To begin fertilization, the sperm cell weaves past follicular cells and binds to the Zona Pellucida. A rise in ________ inside the sperm cell triggers the exocytosis of the ________, which contains hydrolytic enzymes.

A

Calcium

Acrosome

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13
Q

Hydrolytic enzymes contained in the acrosomal cap are released. These enzymes locally dissolve the _______ _______. The whip-like action of the tail pushes the sperm head toward the oocyte membrane.

A

Zona Pellucida

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14
Q

With the head of the sperm now lying sideways (on oocyte membrane), _________ on the oocyte surround the sperm. The two membranes fuse. The content of the sperm cell enter the oocyte, and the sperm cell membrane remains behind.

A

Microvilli

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15
Q

A rise in calcium inside the oocyte triggers the ________ _______, in which there is exocytosis of granules that previously lay immediately beneath the plasma membrane. The enzymes released lead to changes in the Zona Pellucia proteins, causing the Zona Pellucida to harden, preventing the entry of other sperm cells.

A

Cortical Reaction

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16
Q

The rise in calcium inside the oocyte induces the completion of the oocytes second meiotic division and the formation of the second ________ ________, which usually lies next to the first one.

A

Polar Body

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17
Q

The head of the sperm enlarges to become the male ________. The male and female _________ then fuse. This initiates the first embryonic cleavage and begins development.

A

Pronucleus

Pronuclei

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18
Q

Cumulus cell matrix (corona radiata) matrix is predominantly hyaluronic acid. Sperm digest this via membrane bound __________.

A

Hyaluronidase

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19
Q

Zona Pellucida is comprised of what glycoproteins?

A

ZP1
ZP2
ZP3
ZP4

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20
Q

Sperm contains ______ receptors (available after capacitation). Binding of these receptors to the _______ on Zona Pellucida triggers acrosome reaction.

A

ZP3

ZP3

21
Q

The ________ ________ occurs when the inner sperm plasma membrane fuses with the outer acrosomal membrane to release contents of the acrosomal vesicle. The enzymes in the acrosomal vesicle digest the Zona Pellucida. Sperm can enter the holes created in the Zona Pellucida.

A

Acrosome Reaction

22
Q

Sperm reaches the plasma membrane of the oocyte. Sperm possesses a protein called ________ that binds to its receptor on the oocyte. The entire sperm then enters the egg during fusion, and sperm DNA instantly de-condenses. A membrane called _________ forms around the DNA.

A

Izumo

Pronucleus

23
Q

Briefly describe week 1 of embryonic development.

A

Embryo undergoes cleavage, which means there is cell division without growth.

Embryo reaches 16 cell stage called Morula = Day 3
Early Blastocyst = Day 4
Implantation = Day 6-8

24
Q

During embryonic cleavage, the individual cells are called _________. Mitotic divisions maintain 2N (diploid) complement. Cells become smaller and are _________. Embryo reaches 16-cell ________ by day 3.

A

Blastomeres
Totipotent
Morula

25
Q

The outer cells of the morula increase cell-cell adhesion via desmosomes and tight junctions. These form the __________. Increases Na+ transport and osmosis to form a _________.

A

Trophoectoderm (Trophoblast)

Blastocele

26
Q

A later blastocyst has inner cells that become the _______ _______ _______. These will form the embryo proper and are pluripotent.

A

Inner Cell Mass

27
Q

Blastocyst (embryo) _________ from the Zona Pellucida prior to implantation must occur. Trophoblasts secrete proteases that digest the Zona Pellucida. Inability to do this can result in infertility, and if it occurs prematurely it can result in abnormal implantation.

A

Hatching

28
Q

T/F. The Blastocyst will begin synthesizing and secreting molecules that promote maintenance of pregnancy, promote implantation, and placental development. Also secrete _________ and _________ factors.

A

Immunosuppressive

Immunoregulatory

29
Q

This is secreted by trophoblasts and syncytiotrophoblasts. It’s measurable in blood at about 8 days post ovulation. Structure closely related to LH.

A

hCG (Human Chorionic Gonadotropin)

30
Q

hCG prevents involution of the _______ _______, which prevents menstruation and leads to increased secretion of progesterone and estrogen.

A

Corpus Luteum

31
Q

hCG has an autocrine growth factor, which stimulates _________ growth and development and _________ growth.

A

Trophoblast

Placental

32
Q

What are the stages of implantation?

A

Apposition
Attachment
Invasion

33
Q

This stage of implantation is the contact between the endometrium and trophoblasts. Typically in a crypt in endometrium. The inner cell mass rotates near the endometrial epithelium.

A

Apposition

34
Q

This stage of implantation occurs when trophoblast cells adhere to the luminal endometrial epithelium. There is interaction between surface proteins on trophoblasts and epithelial cells. This initiates changes in endometrial stroma (decidualization).

A

Attachment

35
Q

This occurs during the attachment stage of implantation. It is the initiation of changes in endometrial stroma, including increased vascular permeability, intracellular matrix composition, and stromal cell morphology.

A

Decidualization

36
Q

This stage of implantation is the degradation of endometrial epithelial cells and trophoblast fusion and formation of syncytiotrophoblasts (multinuclear, multicellular syncytium). Syncytiotrophoblast protrudes through basement membrane and reaches endometrial stroma.

A

Invasion

37
Q

Syncytiotrophoblasts have adhesive, invasive, and endocrine functions. They express adhesive surface proteins, ________ and ________. They initially bind to the uterine surface epithelia, and as the embryo implants it binds to components of the uterine ECM.

A

Cadherins

Integrins

38
Q

Syncytiotrophoblast also breaks down ECM with the secretion of matrix ___________ and other hydrolytic enzymes.

A

Metalloproteases

39
Q

Syncytiotrophoblast secretes ________, which maintains viability of corpus luteum (progesterone secretion).

A

hCG

40
Q

The syncytiotrophoblast is highly steroidogenic at 10 weeks. It makes __________ at sufficient levels to maintain pregnancy independently of the corpus luteum.

A

Progesterone

41
Q

As implantation and placentation process, the syncytiotrophoblast functions in phagocytosis and bidirectional __________ transfer of gases, nutrients, and wastes.

A

Placental

42
Q

__________ is the response of maternal stromal cells to invasion and progesterone. Endometrial stroma is transformed into enlarged and glycogen-filled decidual cells.

A

Decidualization

43
Q

In decidualization, the endometrium is now called decidua and it is ready for the implantation of the embryo. The decidua forms an epithelial-like sheet with adhesive junctions that inhibits migration of the implanting embryo. Production of signals that prevents embryo from invading __________.

A

Myometrium

44
Q

An ________ ________ is the implantation somewhere other than the uterine fundus. Most common site is the oviduct (called a _______ _______). No decidualization occurs and invasion is not controlled and can rupture the tissues and cause hemorrhage.

A

Ectopic Implantation

Tubal Pregnancy

45
Q

Placentation occurs when spaces appear within ___________ at about day 9. These spaces are called lacunae, and they break maternal capillaries and are filled with endometrial secretions, maternal blood, and digested matrix for nutrient transfer.

A

Syncytiotrophoblasts

46
Q

In placentation, the proliferation of syncytiotrophoblasts and cytotrophoblasts form lacunae. This is _______ ______.

A

Primary Villi

47
Q

In placentation, mesenchyme cells from extraembryonic mesoderm invade villi (now called chorionic membrane). This is _________ ________.

A

Secondary Villi

48
Q

In placentation, eventually mesenchymal cells form fetal blood vessels de novo. This stage is ________ ________.

A

Tertiary Villi

GIGU - Week 5/6 (STILL QUARANTINE) (11 decks)

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