Developmental Biology Flashcards
(43 cards)
The study of the development of a unicellular zygote into a complete, multicellular organism
embryology
In mammals, an egg can be fertilized within ____ hours after ____. Fertilization occurs in the lateral, widest portion of the ____ where sperm traveling from the vagina encounter an egg.
12-24, fertilization, oviduct
Early embryonic development is characterized by a series of rapid ___ ___ known as ___. These divisions lead to an increase in __ __ without a corresponding growth in ___ ____. Thus cleavage results in progressively ___ cells with an increasing ____ of nuclei to cytoplasm. Cleavage also increases the _____ ratio, thereby improving gas and ___ exchange
mitotic divisions, cleavage, cell number, cell protoplasm, smaller, ratio, surface-area-to-volume, nutrient
The first complete cleavage of a zygote occurs approximately ____ hours after fertilization. The second cleavage occurs after ___ hours, and the third cleavage after approximately ___ hours, at which point the ____ reaches the ____.
32, 60, 72, 8-celled, uterus
As cell division continues, a solid ball of embryonic cells known as the ___ is formed. ____ begins when this ball develops a fluid-filled cavity called the ___, which by the fourth day becomes a hollow sphere of cells called the ____. This is the stage of the embryo that ____ in the uterus.
morula, blastulation, blastocoel, blastula, implants
Emergency contraception works partially by inhibiting the ____ of the ___ in the uterus, which is why it is most effective if taken within _____ hours of the time of potential fertilization
implantation, blastula, 72
In an ___ pregnancy, the embryo implants outside the uterus, for example in the __ ___. An embryo typically cannot be __ for long outside of the uterus, and will __ ___ and ___ may occur. Ectopic pregnancies can be ___ if not caught in time and managed appropriately
ectopic, fallopian tube, maintained, abort spontaneously, hemorrhaging, fatal
After week two, the embryo is fully implanted in the uterus and __ ___ transform the single layer cell layer of the blastula into a ____ structure called a ____. ___ primary ___ layers give rise to specific structures
cell migrations, 3-layered, gastrula, 3, germ
Layer that forms the integumentary system including the epidermis, hair, eye, and nervous system
ectoderm
layer that forms the epithelial linings of the digestive and respiratory tracts, and parts of the liver, pancreas, thyroid and bladder lining
endoderm
layer that forms the musculoskeletal system, circulatory system, gonads, connective tissue, and potions of the digestive and respiratory organs
mesoderm
By the end of gastrulation, regions of the germ layers begin to develop into a rudimentary __ ____. This process is known as ___ and start before week ___. A rod of ____ cells called the ____ develops along the _____ ___ of the embryo just under the ____ layer of the ectoderm. This rod of cells causes the overlaying ectoderm to ____ ___ and form a ___ along the dorsal surface of the embryo.
nervous system, neurulation, 3, mesodermal, notochord, longitudinal axis, dorsal, bend inward, groove
The dorsal ectoderm folds on either side of the ___. These __ ___ grow upwards and finally ___, forming a closed ___ ___. This gives rise to the ___ and __ __. Once the neural tube is formed, it detaches from the __ ____.
groove, neural folds, fuse, neural tube, brain, spinal cord, surface ectoderm
The cells at the tip of each neural fold are called the ___ ___ ___. These cells ___ ___ and give rise to many components of the PNS, including the __ __, __ __, __ __ and __ __.
neural crest cells, migrate laterally, sensory ganglia, autonomic ganglia, adrenal medulla, schwann cells
Sometimes during development, the neural tube does not ___ __, resulting in a condition called ____ ____. The incidence of this can be decreased dramatically if the mother takes __ ___ supplements during pregnancy
close properly, spina bifida, folic acid
During ____, the body organs begin to form. In this process, the cells interact, ___, change -_ __, proliferate and ___.
organogenesis, differentiate, physical shape, migrate
During ___, the organs increase in size, which is a continual process from __ through ____ to ___
growth, infancy, childhood, adulthood
When eggs develop in women and sperm develop in men, which permits reproduction to occur
gametogenesis
The growing fetus receives ___ directly from its mother through a specialized ___ __. This system also supplies ____ and removes ___ ___ and __ ___ as well. The two components of this system are the ___ and the __ __ which both develop in the first few weeks after fertilization
oxygen, circulatory system, nutrients, carbon dioxide, metabolic wastes, placenta, umbilical cord
The placenta and umbilical cord are outgrowths of the four ___ ___ formed during development: the ___, ___, ____, and __ __.
extra-embryonic membranes, amnion, chorion, allantois, yolk sac
The amnion is a thin, tough membrane containing the watery fluid called __ ____. This acts as a __ __ of __ __ during gestation and __ ___ from uterine contractions during labor
amniotic fluid, shock absorber, external pressure, localized pressure
Placenta formation begins with the ___, a membrane that completely surrounds the ____. This structure assists with the transfer of ___ from the mother to the fetus
chorion, amnion, nutrients
A third membrane called the ___, develops as an outpocketing of the ____. Blood vessels of the ___ ___ enlarge and become the __ __ which will connect the fetus to the developing placenta. The __ ___, site of early development of blood vessels, becomes associated with the __ __.
allantois, gut, allantoic wall, umbilical vessels, yolk sac, umbilical walls
Human gestation is approximately ___ ___ long and can be subdivided into ____ ___.
nine months, three trimesters
