Developmental Biology Flashcards
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
During the first weeks, the major ___ begin to develop. The heart begins to beat at approximately ___ days, and soon afterward, the __, ___, __ and ___ start to form. By five weeks, the embryo is __ mm in length, and by six it has grown to ___ mm. The ____ skeleton begins to turn into ____ by the seventh week. By the end of 8 weeks, most of the organs have formed, the ___ is fairly developed, and the embryo is referred to as a ___. At the end of the third month the fetus is about ___ cm long.
organs, 22, eyes, gonads, limbs, liver, 10, 15, cartilaginous, bone, brain, fetus, 9
During the second trimester, the fetus does a lot of ___. It begins to __ __ in the amniotic fluid, its face appears ___, and its __ and __ elongate. By the end of the sixth month, the fetus is ___ cm long
growing, move around, human, fingers, toes, 30-60
The seventh and eighth months are characterized by continued __ ___ and further ___ __. During the ninth month, ____ are transported by highly selective active transport from the mother to the fetus. The __ ___ slows and the fetus becomes less active as it has ___ ___ to move about
rapid growth, brain development, antibodies, growth rate, less room
Childbirth in the first stage, the cervix thins and ____, and the amniotic sac ____, releasing its fluids. In the second stage, __ ____ result in the birth of the baby. The __ ___ is cut after. During the final stage, the uterus contracts, expelling the ___ and the __ __.
dilates, ruptures, rapid contractions, umbilical cord, placenta, umbilical cord
The embryo develops into an adult through the process of maturation, which involves __ __, ___ and ___. The last is complete when all organs reach __ __
cell division, growth, differentiation, adult from
Errors during fetal development
congenital disorders
chemical and biological agents that cause congenital disorders
teratogens
When a mother passes on an infection directly to the offspring during development or during birth
vertical transmission
Other environmental factors that can lead to birth defects include poor ____, ___ and __ __ or restraint
nutrition, radiation, physical trauma
In plant embryology, the zygote divides mitotically to form the embryo which consists of ___ parts
5
the precursor of the upper stem and leaves
epicotyl
seed leaves, dicots have two seed leaves, while monocots only have one
cotyledons
the lower stem and root
hypocotyl
feeds the embryo; in dicots, the cotyledon absorbs it
endosperm
develops from the outer covering of the ovule; the embryo and its seed coat together comprise the seed
seed coat
The ___, which is most seeds develop, is formed from the _____ walls, the base of the ___ and other consolidated flower ____ components. The fruit serves as a means of effective ___ ___ by ___ water, or animals. The seed is released from the ___ and will ___ under proper conditions of temperature, moisture and oxygen
fruit, ovary, flower, pistil, seed dispersal, air, ovary, germinate
Growth in higher plants is restricted to the ____ cells called ___ cells. These tissues undergo active cell reproduction, and gradually ___ and differentiate into cell types characteristic of the species
embryonic, meristem, elongate
Meristem found in the tips of roots and stems; growth in length occurs only at these points
apical meristem
Meristem located between the xylem and phloem which permits the growth in diameter and can differentiate into new xylem and phloem cells.
lateral meritstem / cambium
