Nature and Scope Flashcards
first know embryologist; first known study of comparative developmental anatomy; identified the two major cell division patterns
Aristotle
animals are born from eggs= ___
live birth= ___
producing an egg that hatches inside the body=__
(oviparity)
viviparity
ovoviviparity
two major cell division patterns by which embryos are formed:
holoblasic pattern;
meroblastic pattern
type of cell division pattern in which the entire egg is divided into successively smaller cells, as it is in frogs and mammals
holoblastic pattern
type of cell division pattern as in chicks, wherein only part of the egg is destined to become the embryo, while the other portion—the yolk—serves as nutrition for the embryo)
meroblastic pattern
he concluded that all animals—even mammals—originate from eggs
William Harvey
he was the first to see the blastoderm of the chick embryo; first to notice that “islands” of blood tissue form before the heart; suggested that the amniotic fluid might function as a “shock absorber”
William Harvey
he published the first microscopic account of chick development
Marcello Malpighi
he built a microscope; discovered sperms in human semen
Anton Van Leeuwenhoek
he saw the mammalian egg under microscope
Karl Ernst von Baer
they postulated that egg and sperm cells and thus equivalent
Matthias Jakob Schleiden and Theodor Schwann
discovered the fusion of sperm and egg nuclei during fertilization in sea urchins; provided a conceptual basis for genetic inheritance and settled the long-standing debate on the role of the egg and sperm in generation of new life
Oscar Hertwig
discovered and understand mitosis; founder of the science of cytogenetics; the nucleus always splits before the cell does; able to visualize the threadlike material (chromatin) as the cells divide
Walther Fleming
he accurately drew pronuclear fusion in mouse
Johannes Sobotta
the man behind Preformation versus Epigenesis
Thomas Hunt Morgan
the form of living things exists, in real terms, prior to their development instead of assembly from parts; generation of offspring occurs as a result of an unfolding and growth of preformed parts
Preformation
embryological theory according to which “organs […] are progressively formed from, or emerge from, an originally undifferentiated, homogenous [material]”
Epigenesis
believed in the relationship between inducer and competent tissues paralleled that of the genes and the cytoplasm
Conrad Hal Waddington
he said that, “Neither cytoplasm nor nucleus can be disregarded: in fact the most important subject to discuss is how they affect each other”
Conrad Hal Waddington
an evolutionary morphologist, argued that some directing substance or substances had to exist to cause the egg of one species to develop differently from that of another species even though the eggs look identical and are in the same environment
William Keith Brooks
this person’s observation linked heredity to development
William Keith Brooks
combined genetics and embryology
B. Ephrussi, G.W. Beadle
is the study of the process by which organisms grow and develop.
Developmental Biology
is the study of the organisms between the one-cell stage (zygote) and the end of the embryonic stage, which is not necessarily the beginning of free living.
Embryology
embryonic development involves (4)
cell division, cell growth, morphogenesis and cell differentiation.
describes the origin and the development of an organism from the fertilized egg to its mature form
ontogenesis
describes the process by which cells acquire a “type”
Cell Differentiation
involves structural and functional divergence of cells as they become specialized during a multicellular organism’s development, dependent on the control of gene expression
Cell Differentiation
two major types of cells:
pluripotent
totipotent
cell that is able to differentiate into many cell types
Pluripotent
cell that is able to differentiate into all cell types
Totipotent
2 examples of totipotent cells and 2 examples of pluripotent cells
Totipotent- zygote and early embryonic cells (mammals)
pluripotent- stem cell, meristematic cells
process by which an unspecialized cell becomes specialized into one of the many cells that make up the body, such as heart, liver or muscle cell
differentiation
Three basic categories of cells that make up the mammalian body
- Germ (Sex) Cells
- Somatic (Body) Cells
- Stem Cells
majority of these cells are diploid (2n) or have two copies of each chromosome
somatic cells
these cells includes most of the cells that make up the human body, such as skin and muscle cells
somatic cells
are any line of cells that give rise to gametes- eggs and spermand are continuous through the generations
Germ line cells
these cells have the ability to divide for indefinite period and to give rise to specialized cells
Stem cells
Morphogenesis came from the Greek morphe “___” and genesis “___”
shape; creation
concerned with the shapes of tissues, organs and entire organisms and the positions of the various specialized cell types
Morphogenesis
it involves an attempt to understand the process that control the organized spatial distribution of cells that arises during the embryonic development of an organism which give rise to the characteristic form of tissues, organs and overall body anatomy
Morphogenesis
Three (3) several important molecules that are important during morphogenesis:
Morphogens
Transcription Factor Proteins
Molecules that control Cell Adhesion
soluble molecules that can diffuse and carry signals that control cell differentiation decisions in a concentration-dependent fashion; they typically act through binding to specific protein receptors
Morphogens
these molecules determine the fate of cells by interacting with DNA; these can be coded for by master regulatory genes and either activate or deactivate the transcription other genes and in turn, these secondary gene products can regulate the expression of still other genes in a regulatory cascade
Transcription Factor Proteins
is the process individual development from a single cell, an egg cell, or a zygote, to an adult organism
Ontogeny
begins when a sperm fertilizes an egg and creates a single cell that
has the potential to form an entire organism
Development
stages of development between fertilization and hatching (or birth) are collectively called ___
embryogenesis.
stages of development (7)
fertilization,
cleavage,
gastrulation,
organogenesis,
hatching (or birth),
metamorphosis,
gametogenesis
involves the fusion of the mature sex cells
Fertilization
(collection of genes that helps instruct the embryo to develop in a manner very similar to its parents
genome
series of mitotic divisions that immediately follow fertilization
Cleavage
In cleavage, enormous volume of zygote cytoplasm is divided into numerous smaller cells called ___
blastomeres
by the end of cleavage, the blastomeres have usually formed a sphere, known as a ___
blastula
after the rate of mitotic division slows down, blastomeres undergo dramatic movements & change their positions relative to one another; this series of extensive cell rearrangements is called ____
gastrulation
embryo is said to be in the ___ stage
gastrula
as a result of gastrulation, the embryo contains ___ that will interact to generate the organs of the body
three germ layers (endoderm, ectoderm, and mesoderm)
once the germ layers are established, the cells interact with one another and rearrange themselves to produce tissues and organs
organogenesis
certain cells will undergo long migrations from their place of origin to their final location
Organogenesis
organism needs to undergo metamorphosis to become a
sexually mature adult
the young organism is called a
larva
in some species, the ___ is the one that lasts the longest, and is used for feeding or dispersal
larval stage
the ___ is a brief stage whose sole purpose is to reproduce
adult
gametes and their precursor cells are collectively called ___
germ cells
germ cells eventually migrate to the __, where they differentiate into ___
gonads; gametes
the process of the fetus passing from the uterus into the outside world
Birth
the act of conceiving or becoming pregnant; synonymous with fertilization
Conception
means “growing within” and refers to the “human offspring in the first eight weeks following fertilization”
Embryo
the first 8 weeks of human development starting with fertilization; characterized by the formation of most major body systems
Embryonic Period
process that starts with the sperm entering the egg or oocyte, and ends with the joining of the female and male DNA within the single cell zygote
Fertilization
the time from the end of eight weeks through the end of pregnancy; during this time the body grows larger and its systems begin to function
Fetal Period
means “unborn offspring” and refers to human offspring from 8 weeks after fertilization until birth
Fetus
the period of time around birth, from week 28 of pregnancy until 7 days after birth
Perinatal Period
period of time following birth
Postnatal
the condition of a female from the time of fertilization of her oocyte until birth, normally lasting 38 weeks for humans (or 40 weeks if measured from a woman’s last menstrual period
Pregnancy
human development occurring between fertilization and birth
Prenatal Development
the period of time from fertilization until birth
Prenatal Period
Three month periods used to divide pregnancy into three stages of approximately equal length
Trimesters
the single-cell embryo that results from the joining of the sperm and oocyte; means “yoked or joined together”
Zygote
