Embryology - Fertilization To Birth And Beyond

Front 1

what are the statistics for reproductive risks?

Back 1

1000 live births per 1350 conceptuses

350 conceptuses either fail to implant of abort spontaneously

30/1000 newborns have distinct anatomical alterations

100/1000 have defects later in life

Front 2

define etiology

Back 2

cause

Front 3

what kind of birth defect is Sirenomelia?

Back 3

mermaid syndrome, multifactorial, maybe apoptosis didn't happen correctly

Front 4

stats of Etiology of birth defects. go!

Back 4

46% known etiology
6% chromosomal eg. down syndrome
8% single gene eg. dwarfism
7% environmental
25% multifactorial eg. spinal bifida

54% unknown etiology

Front 5

what are some examples of environmental etiology?

Back 5

maternal disease (ex: diabetes, 3%)
infections (ex: rubella, 2%)
mecahnical (ex: radiation, 1%)
drugs/chemicals (ex: alcohol, 1%)

Front 6

what is teratology?

Back 6

the science that seeks to understand causes of birth defects aka congenital deformation

Hint 6

a Teratogen is anything that causes a birth defect

Front 7

during which time period is the embryo particularly sensitive to teratogens and why?

Back 7

embryonic period (from conception to 8 weeks). includes organogensis so it can result in malformation of some or all organ systems

Front 8

when does formation and migration of parental primordial germ cells occur?

Back 8

pregenesis

Front 9

in which phase of human development does gametogenesis occur?

Back 9

pregenesis

Front 10

what is teratoma?

Back 10

when germ cells are lodged in extragonadal sites. they may contain hair and skin cells

Front 11

most common trisomy before birth is number _____, after birth is ____, ____, ____

Back 11

16

21 (down syndrome), 18, and 13

Front 12

what is sticky cumulus corona radiata?

Back 12

second human egg shell

Front 13

sperm much undergo what process in the female reproductive tract?

Back 13

capacitation

Front 14

what is capacitation triggered by?

Back 14

bicarbonate in vaginal secretions

Front 15

what 3 barriers do sperm need to penetrate to enter an egg?

Back 15

corona radiata (loosely connected graulosa cells embedded in a sticky mass of hyaluronic acid), zona pellucida, egg plasma membrane

Front 16

what does the sperm need to penetrate the corona radiata?

Back 16

hyaluronidase activity to breakdown the sticky mass of hyaluronic acid

Front 17

what is the zona pellucida composed of?

Back 17

glycoproteins

Front 18

where is the acrosomal vesicle located on sperm?

Back 18

head

Front 19

in what reaction does a receptor on the zona pellucida bind an adhesion molecule on sperm cell?

Back 19

acrosome reaction

Front 20

how does the sperm breakdown the zona pellucida?

Back 20

binding of zona pellucida and sperm cell causes an influx of Ca++ into sperm and exocytosis of enzymes from acrosomal cap that breakdown the zona pellucida

Front 21

what is the 3rd step of the acrosome reaction?

Back 21

exposed proteins on the sperm head can interact with the egg plasma membrane to produce fusion. the sperm pronucleus is added to the egg cytoplasm

Front 22

what is the cortical reaction?

Back 22

the first sperm to penetrate the plasma membrane causes an increase in intracelluar calcium in the ovum. CORTICAL GRANULES respond by releasing their contents into the space outside of the egg. enzymes rapidly alter egg membrane and zona pellucia to prevent polyspermy

Front 23

once fertilized, the cell/egg is now ________ and termed a ________

Back 23

diploid, zygote

Front 24

during compaction, what kind of junctions are found between the outer cells, and which ones are found between the inner cells?

Back 24

tight junctions - outer(cells flatten), gap junctions - inner

Front 25

When do you see the first sign of differention?

Back 25

compaction - outer cells will become placenta, inner cells will become fetus

Front 26

when does a zyogote become a morula?

Back 26

3-4 days after fertilization

Front 27

how many cells does a morula have?

Back 27

16-32

Front 28

what does a blostocyst consist of?

Back 28

inner cell mass(becomes embryo), blostocoel (fluid), trophoblast (cells on the lining of the cell)

Front 29

when does the embryo enter the uterus?

Back 29

3-4 days after fertilzation when it's a blastocyst, embryo is still encased within the zona pellucida (very tough and rigid egg shell)

Front 30

which part of the blastocyst releases enzymes to break down the zona pellucida during hatching?

Back 30

trophoblast

Front 31

what is the zona pellucida degraded by?

Back 31

uterine secretions

Front 32

when does hatching occur?

Back 32

5th or 6th day after fertilization

Front 33

what happens after hatching and which day does it occur?

Back 33

implantation during day 7

Front 34

what are the "week of 2s" that occur during week 2?

Back 34

trophoblast becomes cytotrophoblast and syncytiotrophoblast.

inner cell mass becomes epiblast (amnion) and hypoblast (yolk sac - stores primordial germ cells)

Front 35

what does the yolk sac contain?

Back 35

blood cell precursors, primordial germ cells, and components of umbilicus

Front 36

what is chorion and what is it formed by?

Back 36

outermost sac of placenta, allows exchange between fetal and maternal circulation. comes from cytotrophoblast

Front 37

when does blastogenesis occur?

Back 37

week 3

Front 38

what occurs during blastogensis?

Back 38

formation of the TRILAMINAR embryo

beginning of gastrulation: formation of primitive node/pit, - streak, neural groove and neural plate, of notochord

formation of paraxial, intermediate and lateral plate mesoderm, of somitomeres and somites

Front 39

what cells do the 3 germ layers come from?

Back 39

epiblast cells

Front 40

what part of the body forms from the endoderm?

Back 40

epithelium of GI tract, epithelium of respiratory tract, E of bladder/urethra, liver, gallbladder, pancreas, thymus, thyroid, parathyroid

Front 41

what part of the body forms from the mesoderm?

Back 41

heart, muscles, dermis, connective tissue (bone, cartilage, blood), E of kidneys, E of gonads, E of vessels, adrenal cortex(on to of kidney, produces hormones), mesotheium, internal reproductive organs

Front 42

what part of the body forms from the ectoderm?

Back 42

epidermis, skin, nail, hair, sweat glands, mammary glands, nervous tissue, sense organs, pituitary gland, adrenal medulla(center of the adrenal gland, cells in here synthesize and secrete epinephrine and norepinephrine), lens of the eye, salivary glands, enamel of teeth, E of mouth, E of anus

Front 43

what happens during week 4?

Back 43

neuralation - formation of notochord and nervous system

Front 44

which germ layer is the notochord formed from?

Back 44

mesoderm, hence, chordamesoderm

Front 45

when does the notochordal process occur?

Back 45

day 18-20

Front 46

neural plate in the ectoderm fold to become neural tube during which week?

Back 46

4

Front 47

name the 3 types of mesoderm

Back 47

somites, intermediate mesoderm, lateral mesoderm

Front 48

what are somites?

Back 48

blocks of paraxial mesoderm that flank the neural tube in segments. forms body and limb muscles, cartilage in vertebrae and ribs, cranial bones, and the dermis

Front 49

what does the intermediate mesoderm form?

Back 49

urinary and parts of the genital system

Front 50

what are the lateral plate mesoderm associated with?

Back 50

endoderm inside (splanchnic/visceral)

ectoderm outside (somatic)

Front 51

what are the 2 types of movements of cells during development?

Back 51

chemoattraction (ex: netrins) and chemorepulsion (ex: semaphorins)