Body Plan 01: First Two Weeks of Development Flashcards
Sperm
The male reproductive gamete
Vagina
The entry point of sperm in the female reproductive tract
Cervix
The location in the female reproductive tract where sperm are stored
Oocyte
The female reproductive gamete
What surrounds the oocyte?
The Zona Pelucida and the Cumulus Oophorus
Zona Pelucida
A layer of cross-linked glycroproteins surrounding the oocyte that sperm must penetrate
Where in the uterine tube does fertilization usually occur?
The Ampulla of the uterine tube
Ampulla
The section of the uterine tube where fertilization occurs. It is also the most common site of ectopic pregnancies
Ovary
The location in the female reproductive system where the oocyte (in a follice) grows and matures before ovulation
What path do sperm take to reach the oocyte?
Vagina -> cervix -> uterine cavity -> uterine tube (intramural -> isthmus -> ampulla)
What reproductive complications can arise from scarring of the fallopian tube? Where can these scars originate from?
Scarring of the fallopian tube can restrict the motility of sperm and prevent fertilization. These scars can originate from sexually transmitted diseases
Cumulus oophorus
A layer of cells that surrounds the oocyte. Most of it is shed once the oocyte is fertilized
Corona radiata
A layer of cells that immediately surrounds the zona pelucida. It is the innermost layer of the cumulus oophorus and is not shed with the rest of the cumulus oophorus
Peritoneal cavity
The cavity that the uterus is located in; the cavity where the oocyte is ejected into in ovulation
Fimbriae
The finger like projections at the end of the fallopian tube; they guide the oocyte inside the tube
Infundiblum
The farthest section of the uterine tube. It is next to the ampulla. Fimbriae project from it
Intramural part of the fallopian tube
The uterine part of the fallopian tube
Isthmus
The segment of the uterine tube directly between the intramural and ampulla
Which stage of meiotic division is the oocyte arrested in after ovulation?
Metaphase II
Follice Stimulating Hormone
One of the pituitary cycle hormones. It is secreted by the pituitary gland and is one of the primers for ovulation
Luteinizing Hormone
One of the pituitary cycle hormones. It is secreted by the pituitary gland. An upshoot in LH levels promotes ovulation
Which stage of meiotic division is the oocyte arrested in before ovulation?
Prophase I
Ovulation
The rupture of the follicle and the ejection of the oocyte into the peritoneal cavity
How is the oocyte transported in the fallopian tube?
Peristaltic activity and ciliar transport
Peristaltic activity
The rapid, synchronized contraction of relaxation of muscles down a tube that helps to move the contents of the tube
Estrogen
One of the ovarian cycle hormones. It is secreted by the follice to signal to the endometrium to prepare for a potential implantation. It is then secreted by the corpus luteum to maintain the endometrium lining
Progesterone
One of the ovarian cycle hormones. It is secreted by the corpus luteum to maintain the endometrium lining
Human Chorionic Gonadotropin
[hCG] a hormone secreted by the human embryo to maintain the corpus luteum. It is the hormone tested for in pregnancy tests
Fertilization
The fusion of the cell membranes of the oocyte and the sperm
Zygote
The cell once the two pronuceli have fused
What two roles do the zona pelucida play?
1) protects the oocyte from polyspermy
2) protects the oocyte from implanting in the fallopian tube
When does the oocyte finish its meiotic division?
Once a sperm has penetrated the zona pelucida and docks with the oocyte membrane
Cleavage
Rapid mytotic activity of the zygote that is not accompanied by cell growth
Early Pregnancy Factor
A hormone secreted by the trophoblast of the embryo. It is an immunosuppressant intending to keep the zygote safe from the mother’s immune system
Blastogenesis
Another word for cleavage (Rapid mytotic activity of the zygote that is not accompanied by cell growth)
Blastomeres
The cells that are formed as a result of cleavage
Morula
A ball of cells of the embryo; the direct result of blastogenesis
Ectopic Pregnancy
The implantation of the embryo anywhere besides the endometrium of the uterine wall. It is a medical emergency
Blastocyst
A morula with a fluid-filled cavity inside (blastocyst cavity)
Blastocyst cavity
The cavity that forms in a new blastocyst
How does the blastocyst cavity form?
Na/K pumps create an osmotic pressure that sucks fluid inside the embryo
Hatching
The disintegration of the zona pelucida and corona raidata surrounding the blastocyst as it prepares for implantation
What are the two layers of the blastocyst?
Embryoblast and trophoblast
Blastocyst embryoblast
Also known as the inner cell mass of the blastocyst; forms the eventual embryo
Blastocyst tophoblast
Cells on the outside of the blastocyst that will contribute to the placenta
Embryonic pole
The end of the embryo that contains the inner cell mass
Bilaminar disk
The eventual shape of the inner cell mass in the blastocyst as it implants. Its two layers are epiblast and hypoblast
Bilaminar disk epiblast
The upper layer of the bilaminar disk that contributes to the fetus
Bilaminar disk hypoblast
The lower layer of the bilaminar disk that does not contribute to the fetus
Where does the blastocyst implant?
The endometrium of the uterine wall
When does implantation occur relative to fertilization and LNMP?
7 days/21 days
After implantation, what two layers do the blastocyst trophoblast differentiate into?
Cytotrophoblast and syncytiotrophoblast
Cytotrophoblast
The inner layer of the differentiated trophoblast after implantation. It drives the syncytiotrophoblast
Syncytiotrophoblast
The outer later of the differentiated trophoblast after implantation. It is a syncytium that produces hCG
Syncytium
A cell that is a fusion of many cells, resulting in many nucelii. Syncytiotrophoblast is a syncytium
What are the requirements for implantation?
Receptive endometrium, functional blastocyst, precise coordination between blastocyst and endometrium
What are the three stages of implantation?
Apposition, Adhesion, Penetration
Apposition
The first stage of implantation; the blastocyst is in contact with the endometrium
Adhesion
The second stage of implantation; the blastocyst is anchored to the basal lamina and ECM
Penetration
The third stage of implantation; the blastocyst penetrates and burrows under the endometrium basal lamina
What cell lines are responsible for early placenta formation (immediately after implantation)
Cytotrophoblast and syncytiotrophoblast; syncytiotrophoblast invades uterine stroma
Amniotic cavity
The cavity that is formed and surrounded by the epiblast after implantation
Yolk Sac
The cavity that is formed by the hypoblast lining the blastocyst cavity. The outer layer is lined by cytotrophoblast
Extraembryonic Reticulum
A layer of Extracellular Matrix secreted by the two linings of the yolk sac (hypoblast and cytotrophoblast) and separates the two linings. It creates room for extraembryonic mesoblasts
Extraembryonic mesoblasts
Cells that have budded off the epiblast and migrated to the extraembryonic reticulum. They form the extraembryonic mesoderm
Extraembryonic mesoderm
The differentiated layer between the hypoblast and cytotrophoblast linings of the yolk sac caused by the migrations of extraembryonic mesoblasts. These cells are no longer migratory
Lacunae
Small cavities inside a layer of cells
Chorionic cavity
A cavity formed by the joining of lacunae in the extraembryonic mesoderm
Extraembryonic coelom
Another name for the chorionic cavity
Extraembryonic splanchnic mesoderm
The layer of extraembryonic mesoderm that lines the border between the chorionic cavity and the yolk sac. “Splanchnic” relates to gut tube
Extraembryonic somatic mesoderm
The layer of extraembryonic mesoderm that lines the borders of the amnion and cytotrophoblast. “Somatic” relates to body/skin
Chorion
The somatic layer consisting of extraembryonic mesoderm, the cytotrophoblast, and the syncytiotrophoblast
Heuser Membrane
Divides the hypoblast from extraembryonic mesoblast. It’s also known as the extracoelemic membrane