Basic Embryology - Final Exam Flashcards
gestation
period from fertilization to parturition
parturition
childbirth
conceptus
all the stages of development and products of fertilization
Biological divisions of conceptus
- ovarian cycle begins
(2) weeks - ovulation/fertilization
(8) weeks - embryonic stage
(30) weeks - fetal stage/parturition
fertilization
sperm and egg coming together
occurs in uterine tube (lateral 3rd of it)
sperm viable longer than eggs
zygote
the single celled result of the fusion of sperm and egg via fertilization
morula
a solid ball (16+ blastomeres) of cells (blastomeres) by the 3rd day of the embryonic stage
____ and ___ ____ move the morula through the uterine tube into the uterine cavity by day 4
peristalsis and ciliary action
when does the morula become a blastocyst
by the 5th day
blastocyst
hollow ball of cells composed of: embryoblast, trophoblast, and blastocoel
embryoblast
inner cell mass, becomes embryo
trophoblast
out layer, becomes placenta and extra membranes
blastocoel
fluid filled cavity of the blastocyst
implantation
begins around the 6th day
- blastocyst attaches and embeds into uterine wall
- trophoblast secretes enzymes that digest endometrium
- after about a week, the endometrium completely covers conceptus
bilayer embryonic disc
differentiation
epiblast will become amnion
hypoblast will become yolk sac
gastrulation forms 3 primary germ layers, what are they
ectoderm - from epiblast; nervous tissue and epidermis
mesoderm - between the two layers; muscle, CT, blood
endoderm - from hypoblast; lining GI, respiratory and urinary organs
most organs are formed by the ___ week
8th
fetal stage
continued development of the organs
by end of 7th month there is enough surfactant in lungs to enhance survival
function of the embryonic membrane
protect/nourish the embryo
considered accessory organs
what are the embryonic membranes
- amnion
- chorion
- placenta and umbilical cord
amnion
“bag of waters”
thin, transparent sac that surrounds embryo w/amniotic fluid
amniotic fluid absorbs shock and provides support
chorion
outermost membrane
derived from trophoblast
becomes placenta
placenta
"flat cake" combo of fetal and maternal tissue chorionic villi grow into endometrium decidua is modified endometrium function: exchange of nutrients/waste by diffusion
placental sinus
endometrial capillaries and intervillous spaces
decidua
“falling off”
placentation takes __ months to complete
3 months
umbilical cord
transports blood to/from placenta/fetus
2 arteries, 1 vein, CT
striae
stretch marks
uterus increases in size due to (2)
hyperplasia and hypertrophy
results of the increase in uterus size
overall compression in bladder, IVC, GI tract, thoracic cavity
puerperium
post-delivery recovery; 6 weeks
uterus undergoes involution - reduction back to normal size
obstetrics
“midwife”
branch of medicine dealing w/maternal aid
mammary glands
modified sweat glands surrounded by adipose and CT within superficial fascia
levels of organization of the mammary gland
- mammary gland - secretory portion
- lobe
- lobule
- alveolus - secretory unit
alveolus
little pit
areola
surrounds the nipples; rough area due to modified sebaceous glands
suspensory ligaments
run between lobes from deep fascia to dermis for support
path of milk flow
- alveolus
- lactiferous duct (1/lobe)
- lactiferous sinus
- opens to the surface at nipple
suckling
stimulates contraction of myoepithelial cells within alveolus
“oranges in a mesh bag”
