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