Chapter 28: Pregnancy and Development Flashcards
Where does fertilization occur?
in the Fallopian tubes
From fertilization through week 8, the developing offspring is called _________________
an embryo
From week 9 through birth, the developing offspring is called _________________
a fetus
Before fertilization can occur, sperm must reach the _________________
the ovulated secondary oocyte
What is a fertilized egg called?
a zygote
When does a zygote form?
When the DNA of sperm and egg fuse
An oocyte is fertilizable for up to _________________ and most sperm are viable within the female reproductive tract for _________________
24 hours, one or two days
Sperm must survive the hostile environment of the vagina and become _________________ before fertilzation can occur
capacitated (aka activated)
Hundreds of sperm must release their _________________ to break down the egg’s _________________ and _________________
acrosomal enzymes, corona radiata and zona pellucida
After the sperm goes inside the oocyte and a cortical reaction occurs and prevents
polyspermy (more sperm from entering)
What attracts the sperm to the egg?
positive chemotasxis
After sperm penetration, the secondary oocyte completes _________________
meiosis II
What is cleavage?
a period of rapid mitotic divisions of the zygote without growing in size.
When does cleavage occur?
After the zygote is formed
What does cleavage result in?
a morula
What is a morula?
A ball of cells (the same size as the zygote) called
By day 3-4 of fertilization the morula travels down the falllopian tube and becomes a A ball of cells (the same size as the zygote) called
blastocyst
What is a blastocyst?
a fluid filled hollow sphere. OUter cells are called trophoblast cells and on one side inside there is a mass called “inner cell mass”
What do trophoblast cells form?
eventually becomes the placenta
What 4 things do the inner cell mass form?
1) embryo
2) Amnion
3) Yolk Sac
4) Allantois
Define amnion
bag filled with fluid
what’s made in the yolk sac?
the first red blood cells
What does the allantiois form?
the blood vessels of the umbilical cord (the allantois develops from the gut of the embryo)
Where does the blastocyst burry itself?
into the endrometrius
Once embedded, the blastocyst forms __________
the chorion
What is the chorion?
the outer layer of blastocyst that forms the placenta
How long does it take for the placenta to form?
3 months (1st trimester)
What does the chorion produce?
hCG hormone (human chorionic gonadotropin)
What does hCG do?
keeps the corpus luteum, which keeps estrogen and progesterone levels high)
What hormone do pregnancy tests test for?
hCG
Define blastula
ball of cells that undergoes gastrulation. The blastocyst is converted to a gastrula when the three primary germ layers form.
Define gastrulation
the developmental process that produces the 3 primary germ layers
What forms as a result of gastrulation?
the primitive digestive tract (a tube that goes through the gastula, eventually each end of the tube will be the mouth and the anus)
What are the three germ layers of a gastula? (from outermost layer to the innermost layer)
ectoderm, mesoderm, and endoderm
what does the ectoderm form?
nervous system, pituitary, adrenal medulla, epidermis of skin, eyes, nasal, oral, and anal epithelium
What does the mesoderm form?
muscles, bones, connective tissue, cardiovascular system, lymphatic and blood system, urogenital organs, and dermis of skin
What does the endoderm form?
GI tract and glands (liver, pancreas, gall bladder), urinary bladder, respiratory epithelium
What helps sperm recognize the egg?
bindin
Right before fertilization, the oocyte is still in __________
metaphase 2
What does the Wolffian Duct System make?
it makes male internal organs (epidiymis, seminal vesicles, prostate)
What does the Mullerian Duct System make?
it makes female internal organs (ovaries, uterus, fallopian tubes, vagina)
Which system do embryos have?
both the Wolffian and Mullerian Duct System
if __________ is present, mullerian develops; by default the external organs are __________
no y is present, female (labia, clitoris)
If __________ is present, testes develop, testes in fetus produce __________ and __________
y is present, testosterone and Mullerian inhibiting factor (MIF) (no Mullerian system)
Testosterone locally leads to __________
the Wolffian duct system to develop, which develops male internal organs
Testosterone systematically (in the whole body) leads to __________
the development of the penis (~7 weeks)
The same tissue that develops... the testes= penis= bulbourethral glands= scrotum=
the testes= ovaries
penis= clitoris
bulbourethral glands= vestibular glands (lubrication)
scrotum=labia
There are 2 processes that form sex organs; __________ and __________
one for internal organs and one for external organs
