L2: Clinical Correlates & Cleavage

Question 1

Contraceptives: Barrier Method

Answer 1

condoms containing spermicides
female condom lining vagina

Question 2

Contraceptives: Hormonal Method

Answer 2

estrogen and/or progestin – inhibits ovulating by preventing release of FSH & LH, changing the lining of uterus & thickening cervical mucus = difficult for sperm to enter uterus

Question 3

Contraceptives: Intrauterine Device (IUD)

Answer 3

Hormonal: releases progestin = thicker cervical mucus = less active sperm

Copper: release copper to uterus = prevents fertilization or inhibits fertilized egg from attaching to uterine wall, prevents sperm from entering uterine tubes

Question 4

Contraceptives: Emergency Contraceptive Pill (ECP)

Answer 4

prevents pregnancy if taken 120hrs aft sex; high dose of progestin

Question 5

Contraceptives: Sterilization

Answer 5

Vasectomy (cut them balls)
Tubal Ligation (tie them tubes)

Question 6

Cleavage (or Segmentation)

Answer 6

once zygote has reached 2 cell stage, it undergoes mitotic divisions = inc numbers of cells

cells that become smaller c each cleavage division are known as blastomeres

aft 3rd cleavage, blastomeres maximize their contact c e/o, forming a compact ball of cells held together by tight junctions (process of compaction)

compaction segregates inner cells which communicate extensively by gap junctions, from outer cells

Question 7

Day 1 of Cleavage

Answer 7

fertilized one-celled zygote will go through 2 cell stage

Question 8

Day 2 of Cleavage

Answer 8

4 cell stage

Question 9

Day 3 of Cleavage

Answer 9

12 cell stage

Question 10

Day 4 of Cleavage

Answer 10

16 cell stage

Question 11

Morula Formation

Answer 11

Day 4 aft fertilization

continuous division till they form a 16-cell morula (mulberry)

Question 12

Blastocyst Formation

Answer 12

fluid begins to penetrate through the ZP into the intercellular spaces of inner cell mass

single cavity, blastocele forms, so embryo is now called blastocyst

cells of inner cell mass (now called embryoblast) are at one pole

those of outer cell mass (trophoblast) flatten and form the epithelial wall of the blastocyst

Question 13

Day 6 of Cleavage

Answer 13

blastocyst hatches from the pellucid zone, wanders from ampulla through fallopian tube into the uterine cavity, where it embeds itself in the endometrium

fertilized oocyte/embryo is transported via the movement of cilia of tubal epithelium & the contractions of its muscular layer

Question 14

trophoblast attaches to _____

Answer 14

fundus of uterine wall

Question 15

integrin receptors for ____ promote _____, while those for ______ stimulate _____

Answer 15

laminin, attachment; fibronectin, migration

Question 16

molecules also interact along signal transduction pathways to regulate ____ so implantation is result of ___ & ____

Answer 16

trophoblast differentiation; mutual trophoblastic & endometrial action

Question 17

by the end of 1st week of development, human zygote has passed through the ___ & blastocyst stages & has begun ____ in the ____

Answer 17

morula; implantation; uterine mucosa

Question 18

Implantation

Answer 18

process of blastocyst embedding into endometrial lining of uterus (Week 2)

Question 19

at this stage of prenatal development (implantation), the conceptus is called

Answer 19

blastocyst

Question 20

it is by this adhesion that the embryo receives ___ & ___ from the mother to be able to grow

Answer 20

oxygen & nutrients

Question 21

Day 8 of Cleavage

Answer 21

blastocyst is partially embedded in endometrial stroma

in the area over embryoblast, the trophoblast has differentiated into two layers: cytotrophoblast & syncytiotrophoblast

Question 22

cytotrophoblast

Answer 22

inner layer of mononucleated cells (darker green)

Question 23

syncytiotrophoblast

Answer 23

outer multinucleated zone without distinct cell boundaries (lighter green)

digests endometrial cells to firmly secure blastocyst into uterine wall

Question 24

trophoblast secretes ___

Answer 24

hCG or human chorionic gonadotropin hormone

Question 25

hCG/ human chorionic gonadotropin hormone

Answer 25

directs corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses

creates an environment suitable for developing embryo

accumulates in maternal blood stream and excreted in urine