Stages of Early animal development

Question 1

metazoan developmental stages… review

Answer 1

• gametogenesis
• fertilization
• embryonic period (cleavage, gastrulation, organogenesis)
• fetal period
• growth
• later development

Question 2

Gametogenesis

Answer 2

• formation of gametes
• spermatogenesis
• oogenesis

Question 3

four phases of gametogenesis:

Answer 3

• extraembryonic origin of germ cells… migration to gonads
• mitosis to increase number of germ cells
• meiosis to reduce chromosome number
• structural and functional maturation

Question 4

Gametogenesis phase 1

Answer 4

• germ cells form, migrate to gonads

Question 5

Gametogenesis phase 2 and 3

Answer 5

• mitosis to increase germ cells
• meiosis to reduce chromosome number
• SPERMATOGENESIS
• OOGENESIS

Question 6

draw oogenesis diagram, and note the timing of oogenesis

Answer 6

–

Question 7

True or false: in females, meiosis not complete until fertilization

Answer 7

true

Question 8

Gametogenesis phase 4

Answer 8

• structural and functional maturation

Question 9

fertilization accomplishes:

Answer 9

• fusion of gametes to form diploid
• egg/metabolic activation and initiation of development

Question 10

steps of fertilization

Answer 10

• sperm penetrate follicle cell layer
• attaches to zona pellucida
• acrosomal reaction… degrades pellucida
• fusion of sperm + egg membranes… (membrane depolarize… fast block to polyspermy… Ca2+ wave sweeps across cell
• cortical reaction (zona reaction)…. prevention of polyspermy (slow block)
• metabolic activation of egg
• completely of egg meiosis, formation of pronuclei (M+F) and restoration of mitotic cell cycle
• pronuclei fuse

Question 11

zona pellucida

Answer 11

• mass of glycoprotein
• enzymes in acrosome released, digests matrix

Question 12

slow block

Answer 12

• enzymes related to acrosomal vesicle fuse to membrane, release contents

Question 13

cleavage

Answer 13

• rapid cell division, little or no cell growth between divisions

Question 14

cleavage pattern

Answer 14

• different species have different cleavage factors
• deuterostomes: cleavage produces ball of cells with fluid or yolk filled cavity
• completing cleavage = cells have diff identities, symmetry is broken

Question 15

blastomeres

Answer 15

• cells that make up blastula
• a cell produced during cleavage of a fertilized egg

Question 16

blastocoel

Answer 16

• the fluid-filled cavity of a blastula.

Question 17

morula

Answer 17

• a solid ball of cells from which the blastula is formed

Question 18

blastula

Answer 18

• embryo at the early stage of development when it is a hollow ball of cells.

Question 19

blastocyte

Answer 19

• ball of differentiated cells
• end of cleavage, embryo implants in uterine wall

Question 20

What are the relationships that connect cleavage pattern with early life strategy

Answer 20

• food source (transition to free living larva, yolk, placental attachment)
• rate of cell division
• level of maternal genome control

Question 21

maternal control

Answer 21

• cellular processes carried out by transcripts/proteins present in egg prior to fertilization
• allows for rapid cell division

Question 22

differences in cleavage patterns depend on?

Answer 22

• yolk content

Question 23

cleavage pattern determines

Answer 23

• size of blastomeres and configuration (asymmetrical, symmetrical)
• where and how cytoplasmic components are segregated into different blastomeres

Question 24

how does the breaking of symmetry work?

Answer 24

• rotation of cell cortex, shift in pigment
• exposed nonpigmented cytoplasm
• identifies where gastrulation begins

Question 25

rotational cleavage and compaction

Answer 25

• rotational cleavage: involves a normal first division , giving rise to two daughter cells. one of the daughter cells divides , whilst the other divides equatorially. (four daughter cells)

compaction: very compacted cells, cells on outside are different from cells on inside

Question 26

components of blastocyte

Answer 26

• inner cell mass (embryonic stem cells)
• trophoblasts (outer cells): structural component of placenta

Question 27

changes in embryo as it moves through cleavage?

Answer 27

• increases in diameter, volume, surface area

Question 28

Gastrulation

Answer 28

• extensive rearrangement of cells
• integrated cell and tissue movement
• blastula transforms: 3 layer embryo w primitive gut
• gastrula
• process may look different in species

Question 29

gastrula:

Answer 29

• gastrulation stage embryo

Question 30

gastrulation results in:

Answer 30

• formation of 3 germ layers
• form primitive gut (archenteron) (blastopore)
• tube within a tube body plan
• elongated rostrocaudal axis

Question 31

germ layers

Answer 31

• ectoderm
• mesoderm
• endoderm

Question 32

epithelial cells

Answer 32

• strong interactions with other cells (adhesion) and ECM, stationary, polar

Question 33

mesenchymal cells:

Answer 33

• weak/ no interaction with other cells, mobile, no cell polarity

Question 34

ectoderm examples

Answer 34

• outer surface (epidermal cells of skin)
• central nervous system (neuron of brain)
• neural crest (pigment cell - melanocyte)

Question 35

meso derm examples

Answer 35

• dorsal… notochord
• paraxial… bone tissue
• intermediate… tubule of the kidney
• lateral… red blood cells…
• head… facial muscle

Question 36

endoderm examples

Answer 36

• digestive tube… stomach cell
• pharynx… thyroid cell
• respiratory tube…lung cell

Question 37

germ cells

Answer 37

• sperm, egg

Question 38

ectoderm definition

Answer 38

• outermost layer of gastrula
• nervous and sensory systems, epidermis

Question 39

mesoderm

Answer 39

• partly fills space between ectoderm and endoderm
• skeletal, muscle, circulatory systems
• excretory and reproductive system
• dermis, inner layer of skin
• notochord

Question 40

endoderm

Answer 40

• lines archenteron
• epithelial lining of the digestive tract and associated organs (liver, pancreas)
• epithelial lining of respiratory system (lungs)
• thyroid and urinary bladder

Question 41

chicken gastrulation

Answer 41

• lateral folding to give tube within a tube body plan

Question 42

organogenesis

Answer 42

• last stage of embryonic period
• organs of animal body form the 3 embryonic layers

Question 43

organogenesis involves:

Answer 43

• cell differentiation
• morphogenesis

Question 44

cell differentiation

Answer 44

• cells interact with each other and acquire different identities

Question 45

morphogenesis

Answer 45

• segments form and develop specific characteristics
• organized spatial patterns of differentiated cells emerge
• formation of tissues and organs

Question 46

mesodermal structures

Answer 46

• notochord : embryonic backbone… induces signals
• somites

Question 47

ectodermal structures

Answer 47

• neurulation: neural tube..
• from ectoderm, neurulation produces:
• epidermis (eye lens, anterior pituitary)
• neural tube: central nervous system (brain, spinal cord), retina
• neural crest (peripheral nervous system, facial cartilage