Embryology

Question 1

embryology

Answer 1

the study of the development of a unicellular zygote into a complete multicelluar organism

Question 2

Fertilization of vertebrates

Answer 2

an egg can be fertilized within 12-24 hours following ovulation. Occurs in the fallopian tube

Question 3

faternal twins

Answer 3

if more than one egg is fertilized

Question 4

Cleavage

Answer 4

early embryonic development is characterized by a series of rapid miotic divisions known as cleavage. results in progressively smaller cells with an increasing ratio of nuclear to cytoplasmic material.

Question 5

indeterminate cleavage

Answer 5

is one that results in cells that maintain the ability to develop into a complete organism.

Question 6

Identical twins

Answer 6

are the result of an indeterminate cleavage.

Question 7

determinate cleavage

Answer 7

results in cells whose future differentiation pathways are determined at an early developmental stage.

Question 8

differentiation

Answer 8

is the specialization of cells that occurs during development

Question 9

morula

Answer 9

a solid ball of embryonic cells

Question 10

Blastulation

Answer 10

begins when the morula develops a fluid filled cavity called the blastocoel. which by the fourth day becomes a hollow sphere of cells call the blastula.

Question 11

Gastrulation

Answer 11

once the blastula is implanted in the uterus cell migrations transform the single cell layer of the blastula into a three layerd strucutre called gastrula

Question 12

Gastrula

Answer 12

composed of three primary germ layers that are responsible for the differential development of the tissues, organs and systems of the body at later stages of growth. ectoderm, endoderm and mesoderm

Question 13

Ectoderm

Answer 13

itegument (including the epidermis,hair , nails, and epithelium of the nose, mouth, and anal canal), the lens of the eye, the retina and the nervous system

Question 14

Endoderm

Answer 14

epithelial linings of the digestive and respiratory tracts and parts of the liver, pancreas, thyroid and bladder lining

Question 15

Mesoderm

Answer 15

musculoskeletal system, circulatory system, excretory system, gonads, connective tissues throughout the body and portions of the respiratory organs.

Question 16

External development

Answer 16

the early development of many animals occurs outside of the mothers body, on land or in the water.

Question 17

Egg shells

Answer 17

provide protection for the developing embryo outside the mothers body. Consisting of chorion, allantois, amnion and yolk sac

Question 18

Chorion of egg shells

Answer 18

lines the inside of the shell, it is the moist membrane that permits gas exchange

Question 19

Allantois of egg shells

Answer 19

saclike structure that is involved in respiration and excretion and it contains numerous blood vessels to transport O2, CO2, water, salt and nitrogenous wastes

Question 20

Amnion of egg shells

Answer 20

this membrane encloses the amniotic fluid which keeps the embryo safe from shock

Question 21

Yolk sac

Answer 21

encloses the yolk. Blood vessels in the yolk sac transfer food to the developing embryo

Question 22

Nonplacental internal development

Answer 22

marsupials and some tropical fish develop in the mother without a placenta. Without a placenta exchange of food and oxygen between the young and the mother is limited.

Question 23

Placental internal development

Answer 23

the growing fetus receives oxygen directly from its mother through a specialized circulatory system. which also supplies nutrients and removes waste. key component is the placenta and the umbilical cord

Question 24

The placenta and the umbilical cord are out growths of _

Answer 24

four extra-embryonic membranes formed during development: the amnion, chorion, allantois and yolk sac

Question 25

The amnion in humans

Answer 25

is a thin tough membrane containing a watery fluid called amniotic fluid. Amniotic fluid acts as a shock absorber of external pressure and localized pressure from uterine contractions

Question 26

the chorion in humans

Answer 26

the placenta formation begins with the chorion, a membrane that completely surrounds the amnion

Question 27

allantois of the human

Answer 27

develops as an out-pocketing of the gut. blood vessels of the allantoic wall enlarge and become the umbilical vessels, which connect the fetus to the developing placenta

Question 28

yolk sac of humans

Answer 28

the site of early development of the blood vessels becomes associated with the umbilical vessels

Question 29

labor

Answer 29

a series of strong uterine contractions. three distinct stages. first stage the cervix thins and dilates and the amniotic sac ruptures releasing fluids. second stage is characterized by rapid contractions resulting in birth. third is followed by expelling of the placenta and umbilical cord

Question 30

embryo parts of seed formation

Answer 30

epicotyl, cotyledons, hypocotyl, endosperm, and seed coat

Question 31

epicotyl

Answer 31

this is the precursor of the upper stem and leaves

Question 32

cotyledons

Answer 32

these are the seed leaves. Dicots have two seed leaves while monocots have only one.

Question 33

hypocotyl

Answer 33

this develops into the lower stem and root

Question 34

endosperm

Answer 34

the endosperm grows and feeds the embryo. In dicots the cotyledon absorbs the endosperm

Question 35

seed coat

Answer 35

develops from the outer covering of the ovule. the embryo and its seed coat together comprise the seed

Question 36

Seed dispersal

Answer 36

the fruit is formed from the ovary walls and other parts of the plant is the means of seed dispersal. it enables to the seed to be carried more frequently and effectivley

Question 37

meristem cells

Answer 37

these tissues undergo active cell reproduction. gradually the cells elongate and differentiate into cell types characteristic of the species

Question 38

apical meristem

Answer 38

found in the tips of roots and stems. growth and length only occurs at these points

Question 39

lateral meristem

Answer 39

the lateral meristem or cambium is located between the xylem and pholem. this tissue permits growth in the diameter and can differentiate into xylem and pholem cells. predominant in woody dicots

Question 40

Embryonic development stages

Answer 40

1) fertilization 2) cleavage 3. Morula 4. Blastula 5. Gastrula 6. Extra embryonic development 7. Organogenesis

Question 41

Notochord

Answer 41

Cells of dorsal surface of mesoderm germ layer, form this stiff Rod that provides support

Question 42

Neural tube

Answer 42

In Ectoderm layer above the notochord, a layer of cells forms the neural plate the plate indents forming a neural grove which becomes a neural tube (encasing CNS) and neural crest creating teeth bones and more

Question 43

Blastocyst

Answer 43

Consists if two parts- outer ring trophoblast and inner cell mass called embryonic disc

Question 44

Trophoblast

Answer 44

Outer ring the embeds into the endometrium, and produces HCG, then becomes the chorion

Question 45

Embryonic disc

Answer 45

Inner cell mass that clusters at one pole and flattens into embryonic disk. A primaries streak occurs, gastrulation follow and then extraembryonic membranes form (except chorion)