Embryogenesis and Development Flashcards
joining of sperm and ovum
fertilization
site fertilization usually occurs in the fallopian tube
ampulla
uses acrosomal enzymes to penetrate the corona radiata and zona pellucida
sperm
established by sperm when it contacts oocyte’s plasma membrane, then injects its pronucleus
acrosomal apparatus
when sperm first penetrates it causes release of calcium ions preventing additional sperm from fertilizing the egg and increasing the metabolic rate of the resulting diploid zygote
cortical reaction
result from fertilization of two eggs by two different sperm
fraternal (dizygotic) twins
result from splitting of a zygote in two
identical (monozygotic) twins
refers to early divisions of cell in embryo, result in more smaller cells, but no change in volume
cleavage
what zygote becomes after first cleavage because it is no longer unicellular
embryo
cleavage that results in cells capable of becoming any cell in organism
indeterminate cleavage
cleavage that results in cells committed to differentiating into a specific cell type
determinate cleavage
solid mass of cells seen in early development
morula
has fluid filled center called blastocoel with two different structures: trophoblast (becomes placental structures) and inner cell mass (becomes the developing organism); implants in endometrial lining and forms the placenta
blastula (blastocyst)
contains chorionic villi which penetrate endometrium and create interface between maternal and fetal blood
chorion
supports embryo before placenta is established
yolk sac
involved in early fluid exchange between embryo and yolk sac
allantois
lies just inside chorion, produces amniotic fluid
amnion
connects developing organism to placenta
umbilical cord
archenteron is formed with a blastopore at the end, as archenteron grows through blastocoel it contacts opposite side establishing three primary germ layers
gastrulation
becomes epidermis, hair, nails, and epithelia of nose, mouth, and anal canal, as well as nervous system and lens of eye
ectoderm
becomes much of musculoskeletal, circulatory, and excretory systems, also gives rise to gonads and muscular and connective tissue layers of digestive and respiratory systems, as well as adrenal cortex
mesoderm
becomes much of epithelial lining of respiratory and digestive tracts and parts of pancreas, thyroid, bladder, and distal urinary tracts
endoderm
development of nervous system, begins after formation of germ layers
neuralation
induces group of overlying ectodermal cells to form neural folds surrounding neural groove
notochord
forms when neural folds fuse, becomes CNS
neural tube
contained in tip of each neural fold, becomes PNS
neural crest cells
substances that interfere with development
teratogens
occurs as a result of determination and differentiation
cell specialization
commitment to specific cell lineage, may be accomplished by uneven segregation of cellular material during mitosis or with morphogens (promote development down a specific line), cells must have competency to respond to a specific morphagen
determination
changes a cell undergoes due to selective transcription to take on characteristics appropriate to its cell line
differentiation
cells capable of developing into various cell types, classified by potency
stem cells
able to differentiate into all cell types, including three germ layers and placental structures
totipotent cells
able to differentiate into all three germ layers and their derivatives
pluripotent cells
able to differentiate only into a specific subset of cell types
multipotent cells
occurs through number of different signaling methods
cellular communication
signaling method of cellular communication that releases factors to promote differentiation of a component responder
inducer
signaling method of cellular communication where signals act on the same cell that released the signal
autocrine
signaling method of cellular communication where signals act on local cells
paracrine
signaling method of cellular communication where signals act through direct stimulation of adjacent cells
juxtacrine
signaling method of cellular communication where signals act on distant tissues after traveling through the blood system
endocrine
peptides that promote differentiation and mitosis in certain tissues
growth factors
term for when two tissues both induce further differentiation in each other
reciprocal induction
programmed cell death via formation of apoptotic blebs, can be used for sculpting certain anatomical structures
apoptosis
ability of an organism to regrow certain parts of body
regenerative capacity
result of multiple molecular and metabolic processes, including shortening of telomeres during cell division
senscence
site of nutrient, gas, and waste exchange; serves endocrine functions, secreting estrogen, progesterone, and human chorionic gonadotropin (hCG)
plancenta
serves as immune protection against many pathogens, antibodies are transferred from mother to child
placental barrier
allow oxygen and carbon dioxide to be passively exchanged
concentration gradients
has higher affinity for oxygen than adult hemoglobin (HbA), affinity assists in transfer and retention of oxygen into fetal circulatory system
fetal hemoglobin (HbF)
carry deoxygenated blood from the fetus to the placenta
umbilical arteries
carries oxygenated blood from placenta back to the fetus
umbilical vein
differs from adult version by having three shunts
fetal circulatory system
fetal circulatory system:
connects right atrium to left atrium, bypassing lungs
foramen ovale
fetal circulatory system:
connects pulmonary artery to aorta, bypassing lungs
ductus arteriosis
fetal circulatory system:
connects umbilical vein to inferior vena cava, bypassing liver
ductus venosus
when organogenesis occurs during pregnancy (development of heart, eyes, gonads, limbs, liver, brain)
first trimester
when tremendous growth occurs, movement begins, face becomes distinctly human, and digits elongate during pregnancy
second trimester
when rapid growth and brain development continue and transfer of antibodies to fetus during pregnancy
third trimester
cervix thins out, amniotic sac ruptures; uterine contractions (coordinated by prostaglandins and oxytocin) result in birth of fetus; placenta and umbilical cord are expelled
birth
