Lesson 13 Definitions Flashcards
gamete
ova/sperm
sperm
formed in the testes, produces four viable cells of the same size, each propelled by a flagellum
fertilization
occurs in fallopian tube, consists of the penetration and fusion phases
corona radiata
supplies proteins to cell
zygote
fertilized egg cell with diploid number
cleavage
first cell division
blastocyst
fertilized egg after five or six days
gastrula
forms during first two weeks
embryo
zygote after first cell division
neural tube
the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord
neurulation
the folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube. The embryo at this stage is termed the neurula.
hox genes
genes that specify regions of the body plan of an embryo along the head-tail axis of animals. Hox proteins encode and specify the characteristics of ‘position’, ensuring that the correct structures form in the correct places of the body.
fetus
embryo after 8 weeks
yolk sac
food source until hatching (helps form umbilical cord in humans)
allantois
stores metabolic wastes of embryo
amnion
fluid filled sac that cushions embryo
chorion
fetal part of placenta. lines the inner surface of the shell, participates in gas exchange. (chorionic villi interact with placenta in mammals)
placenta
membrane that separates the mother’s blood from the baby’s blood
decidua basalis
mother’s part of placenta
umbilical cord
connects baby to placenta
ectoderm
skin, brain
mesoderm
muscle, blood
endoderm
inner organs
