Plant and Animal Development - Exercise 10 - PowerPoint Presentation

Slide1

Plant and Animal Development - Exercise 10

Objectives

Identify Starfish Development using the models and microscope slides.

Understand when sperm penetrates the egg, it creates a membrane barrier.

-Understand purpose

of umbilical

cord and placenta in mammals.

-Know primary germ layers.Slide2

Pages 1 - 4 is skipped unless your instructor

wants you to know this stuff, you have to

do this on your own. You will learn more

about this in BI108, if you take the class.Slide3

All multicultural, sexually reproducing animals utilize gametes to transmit genetic information to their offspring.

The contribution to the offspring is limited to their nuclear contends - I.e., a haploid set of chromosomes. Egg cells are typically much larger than sperm cells. They, too, contribute a haploid set of chromosomes to the offspring; however, they may also provide nutrients (for energy and growth)

, in the form of yolk, to sustain the development of the offspring to the point that it can obtain its own food.

There are several different types of eggs with respect to the amount and distribution of yolk

.Slide4

Those organisms that live independently will usually pass through one or more immature larval stages before reaching their final mature form

. The more yolk that an egg possess, the more time the embryo has to develop tissues and organs that will enable it to live indecently. Organisms that develop on land must be protected from desiccation (drying out) by remaining in mother’s body or have a protective barrier. Also, there must be enough yolk to support a considerable amount of development, as occurs in bird and reptile eggs, for example.Slide5

The fusion of the haploid sperm nucleus with the haploid egg nucleus at fertilization produces a diploid

zygote

,

which is the beginning of new organism.

The first stage of development is

cleavage

,

during which the cells rapidly dividing by mitotic cell division without increase their mass

.

Each of the cells is called a

blastomere

. The embryo, therefore, increases its cell number, but it does not grow in overall size.

As cleavage progresses, the

blastomeres

tend to become peripherally located, leaving a space or cavity (the

blastocoel

)

in the center of the embryo. Cleavage ends with the formation of a hollow ball of cells called a

blastula

. Slide6

The next process is called

morphogenesis

.

During this, the shape and body form of the organism will be produced and the embryo will begin to grow an enlarge.

Some cells will migrate to other locations in the embryo. This movement of embryonic cells is referred to as

morphogenesis movements

. The movements coupled with the continued multiplication of cells will produce three layers of cells.

The three specialized cell layers are called the

primary germ layers

.Slide7

Ectoderm

: Outermost layer. It gives rise to the

skin

and associated structure and the

nervous system

.

Mesoderm

: Middle layer. It gives ruse to muscle, bone, tendons, blood, and other

connective tissues

. The

kidney, gonads and the heart

.

Endoderm

: Inner layer. It gives rise to the lining of the organs of the

digestive system

, the

lining of the lungs, liver, cell of the pancreas

and produce digestive enzymes.Slide8

Morphogenesis is initiated by the inward migration of a group of cells towards the interior of the embryo into the

blastocoel

.

The particular morphogenesis movement is referred to as an

invagination

,

and during this time the embryo is called a

gastrula

.

The

invagination

(aka

gastrulation

)

creates an opening to the outside of the embryo which is called the

blastopore

. As

gastrulation

progresses, the inward moving cells from an internal cavity called the

archenteron

,

which is continuous with the

blastopore

.

Once the primary germ layers have formed,

differentiation

of these cells into mature tissues begin to occur.Slide9

Starfish Development ModelsSlide10
Slide11

Cleavage

Early cleavage stage embryos (2,4, and 8 cell stages)

Early cleavage stage embryos (2,4, and 8 cell stages)Slide12
Slide13

CleavageSlide14
Slide15
Slide16
Slide17

GastrulaSlide18

Development in placental mammals

Nearly unique to most mammals in the animal kingdom is the protection and nourishment of the embryo (fetus) within the uterus of the mother by assistance of a complex organ called the placenta.

There is no active, feeding larval stage in mammals, because the mother and the placenta provide food for embryonic growth through the umbilical cord.

Embryos are attached to the umbilical cord with the placenta.Slide19

Various mammals in their placenta.

-What’s the thing cord that attaches the placenta to the animal for nutrients?Slide20

The

Umbilical cord…Slide21

Chicken Embryonic StagesSlide22

Sperm

Identify: Sperm head & flagellumSlide23

Starfish embryos, various stages Fig 110a - Rust

Early Starfish Development

Females and males shed their gametes into water where fertilization occurs. These

slides contain a mixture of all of the various embryonic stages in whole mounts.Slide24

Single Egg cell – Unfertilized egg

Before sperm penetration of the egg occurs, the nucleus and a single nucleolus are clearly visible in the unfertilized egg cell.

Label: nucleus, nucleolus, nuclear membrane, cytoplasmSlide25

Zygote

Fertilized egg:

Once the sperm penetrate the egg, the egg cell (which was actually a secondary

oocyte

) completes meiosis. The nucleus will no longer be visible. A

fertilization membrane

is formed,

which prevents any other sperm cells from entering the egg.

Label: Fertilization membraneSlide26

Two Cell Stage Fig. 110C - RUST

When a sperm has

gotten into the egg,

the egg will create a

membrane barrier to

prevent other sperm

from entering.Slide27

Cleavage

Early cleavage stage embryo

(2,4, and 8 cell stages)Slide28

Early Blastula Figure 110g - RUSTSlide29

Late Blastula Figure 110h - RUSTSlide30

Cleavage Figures 110i – 110k - RUST

Label:

Blastopore

&

BlastocoelSlide31

Gastrula Figure 110l - RUST

Label:

Blastocoel

, archenteron,

blastopore

, ectoderm, endoderm, & mesoderm..

Late gastrulaSlide32

Larva of Starfish Figure 110m - RUST

Label mouth, esophagus, stomach, intestine, and anusSlide33

ChickSlide34

Page 10 – Lab Book - Questions

1. What stage of development is characterized by an increase in the number of cells but no overall increase in the mass of the embryo?

2. Which of the starfish stages that you drew marks the beginning of morphogenesis?Slide35

Page 10 – Lab Book - Questions

1. What stage of development is characterized by an increase in the number of cells but no overall increase in the mass of the embryo?

Cleavage

2. Which of the starfish stages that you drew marks the beginning of morphogenesis?

GastrulaSlide36

Page 11 – Lab Book - Questions

Yolk in animal eggs is used for food energy for

growth of the embryo until the embryo hatches or

becomes a large larva. The starfish egg has almost no

yolk and develops into a larva with a complete digestive

tract fort eight hours after fertilization. A frog egg has a

moderate amount of yolk and develops into a larva

(tadpole) 10 days after fertilization. A bird egg has a very

large amount of yolk and doesn’t hatch for three weeks.

Does there seen to be any connection between the

amount of yolk present in a starfish egg and the rate at

which the larval stage and its digestive system develops in

the starfish embryo? Explain.Slide37

Page 11 – Lab Book - Questions

Yolk in animal eggs is used for food energy for growth of the

embryo until the embryo hatches or becomes a large larva. The

starfish egg has almost no yolk and develops into a larva with a

complete digestive tract fort eight hours after fertilization. A frog egg

has a moderate amount of yolk and develops into a larva (tadpole) 10

days after fertilization. A bird egg has a very large amount of yolk

and doesn’t hatch for three weeks. Does there seen to be any

connection between the amount of yolk present in a starfish egg and

the rate at which the larval stage and its digestive system develops in

the starfish embryo? Explain.

The more yolk, the longer it takes

to develop into a larva and your digestive system isn’t fully

developed.Slide38

Page 12 – Lab Book - Questions

7. Name several functions of the placenta.

9. Compare how the sperm is transported to the egg in a flowering plant and how the sperm travels to the egg of a starfish. Slide39

Page 12 – Lab Book - Questions

7. Name several functions of the placenta.

Provides protection, nutrients (food & oxygen). It

helps to remove carbon dioxide and wastes from

fetus.

9. Compare how the sperm is transported to the egg in a flowering plant and how the sperm travels to the egg of a starfish.

In starfish the sperm is just thrown to the water and it swims towards the egg to fertilize it.