Introduction Part 2

Question 1

Three major approaches to studying embryology:

Answer 1

Anatomical approaches
Experimental approaches
Genetic approaches

Question 2

4 Anatomical approach:

1._____ Study of how anatomy changes during development of different organisms
2._____ Study of how changes in development may cause evolutionary change
3.____ The study of birth defects
4.____ Seeks to describe developmental phenomena in terms of equations

Answer 2

Comparative embryology

Evolutionary embryology

Teratology

Mathematical modeling of development

Question 3

___________- observed different ways animals are born:

____ Eggs hatch outside the mother
____ Growth in placenta live brith
____ Eggs hatch inside the mother

Answer 3

ARISTOTLE:
Oviparity (chicken)
Viviparity (live birth)
Ovoviviparity (shark)

Question 4

ANATOMICAL APPROACH

An application of _____________:

_____ identified the two major cell division patterns by which embryos are formed:
1. _____
The entire egg is divided into smaller cells like in frogs and mammals
2. _____
Part of the egg becomes the embryo and the other serves as nutrition like reptiles and birds

Answer 4

Comparative Embryology

ARISTOTLE

1. Holoblastic pattern of cleavage
2. Meroblastic pattern of cleavage

Question 5

EVOLUTIONARY EMBRYOLOGY:

______:

_____ Share a close evolutionary relative with similar structure, like a human and seal limb.

____ Similar purpose but not necessarily same structure. Like a butterfly and a bird both flying. Or like a Shark(fish) and dolphin (mammal)

Answer 5

Embryonic homologies

Homologous

Analogous

Question 6

TERATOLOGY:

ex: ______

• Caused by a dominant mutation in a ___ on the long arm of the chromosome.
• Causes the proliferation and migration of neural crest cells, germ cell precursors, and blood cell precursors

Answer 6

Piebaldism

gene (KIT)

Question 7

TERATOLOGY:

_____
- Abnormalities caused by exogenous agents
- Agents responsible for it are called ____

Answer 7

Disruptions

Teratogen

Question 8

study of how environmental agents disrupt normal development

Answer 8

teratology

Question 9

TERATOLOGY:

ex: _____

• Hypnotic agent widely used in Europe
• Caused 7000 infants to be born with ____ or ____
• Limb abnormalities

Answer 9

Thalidomide

Thalidomide syndrome or Phocomelia

Question 10

TERATOLOGY

• _____ and ____ made observations for Thalidomide
• ____ Documented the period of susceptibility which is ___ - ___ days postconception and ____-_____ days past menstruation
• ____ Grammy nominated german singer with Phocomelia

Answer 10

McBride and Lenz

Nowack; 20-36 days and 34-50 days

Thomas Quasthoff

Question 11

HISTORICAL BACKGROUNDS:

_____ in 5th century bc

• He tried to explain development in terms of the principles of heat, wetness, and solidification
• Believed embryo began development by extracting moisture and breath from mother.
• Condensations and fires responsible for the development of bones, belly, and circulation in the embryo and fetus.
• Supported the view that human fetus gained nourishment by sucking blood

Answer 11

Hippocrates

Question 12

HISTORICAL BACKGROUNDS:

_____
Established “Embryology” as an independent field

Figured out the functions of ____ and the ____

Defined ____ and ____

Answer 12

Aristotle

Placenta and the Umbilical cord

Epigenesis and Preformation

Question 13

HISTORICAL BACKGROUNDS:

_____
Concluded that all animals originate from eggs (even mammals)

First to see the ___ (layer of cells that develop on the surface of the yolk which gives rise to the disk where the embryo develops) of the chick embryo

___________: Motto on the frontpiece of his On the Generation of Living Creatures

Answer 13

William Harvey (1651)

Blastoderm

Ex ovo omnia! ( all from eggs)

Question 14

HISTORICAL BACKGROUNDS:

_____ (1672)

Drew first micrograph of developing chick embryos and published the first microscopic account of chick development

Identified the neural groove (precursor of the neural tube), the muscle-forming somites, and the first circulation of the arteries and veins – to and from the yolk.

Ignited debate within preformationist vs epigenesist

Answer 14

Marcello Malphigi (1672)

Question 15

How debate between epigenesis and preformation

1._____
The body is already patterned in miniature, within the early embryo

2._____
The structures of the body arise de novo (from scratch) at each generation during embryogenesis

Embryo develops progressively from an undifferentiated egg cell

Answer 15

Preformationism

Epigenesis

Question 16

Preformation or Epigenesis?

• no evolution
• all creations are created at the same time
• Adam contained all human within him
• _____________, 1694
• No external force needed for embryonic development
• fertilization had never been observed
• no cell theory (1600s) to provide lower limit to the size of organisms

Answer 16

Preformation
- Homunculus Hartsoeker

Question 17

DESCRIPTIVE EMBRYOLOGY

______
The first embryologist
Visualized epigenesis of embryonic germ layer

He also discovered _____

Answer 17

Christian Pander

Tissue Interactions (Induction)

Question 18

Embryonic germ layer (3)

______: epidermis, forms the brain nervous system
______: digestive system, lungs
______: muscle, bone, connective tissue, heart, kidney, gonad

Answer 18

Ectoderm: outer layer
Endoderm: inner layer
Mesoderm: middle layer

Question 19

DESCRIPTIVE EMBRYOLOGY:

_____
- the first embryologist
- Observed the development of frogs, salamanders, fish, turtles, birds, and mammals

Discovered ____ in fishes it forms ____ in humans it forms ____, ____, and ____

Answer 19

Heinrich Rathke

Pharyngeal arches
- fish: Gill Apparatus
- human: Jaw, Ears, Vertebrate Skull

Question 20

DESCRIPTIVE EMBRYOLOGY:

____
Found by Heinrich Rathke for the development of the pituitary gland

Answer 20

Rathke’s pouch

Question 21

DESCRIPTIVE EMBRYOLOGY

_____
“Father” of developmental biology

Expanded Pander’s studies on chick embryos

Idnetifies ________ - rod of dorsal - most mesoderm tissue. It divides embryo in right and left sides and instruct ectoderm above it to differentiate into nerve tissue.

discovered Mammalian egg

And differences among different vertebrate embryos

Answer 21

Karl Ernst Von Baer
- notochord

Question 22

Principles of Karl Ernst von Baer:

_____
Example: vertebrates appear very similar shortly after gastrulation
_____
Example: All vertebrates initially have the same kind of skin
_____
Example: human embryo does not turn into a lizard
_____
Embryo of a human is similar to embryos of lower animals

Answer 22

Principles of Karl Ernst von Baer (summarized):

1. GENERAL FEATURES of a large group of animals appear EARLIER IN DEVELOPMENT than the specialized features.
2. LESS GENERAL CHARACTERS develop FROM THE MORE GENERAL, until the most specialized appear
3. EMBRYO of a given species, instead of passing through the adult stages of lower animals, DEPARTS more and more FROM LOWER ANIMALS
4. The EARLY EMBRYO of a higher animal is NEVER LIKE A FULLY FORMED LOWER ANIMAL, but only like its early embryo

Question 23

All vertebrate embryos have (4)

Answer 23

Pharyngeal arches

Notochord

Spinal cord

Primitive kidneys