REPRODUCTION

ASEXUAL REPRODUCTION

Example: Binnary Fission

Budding

Mitosis

SEXUAL REPRODUCTION

Involves the fusion of two gamates

Sperm and eggs produced by same individual

and sometimes by different individuals.

Stages of Reproduction/development

1) Gamate Formation MEIOSIS

Gamates start out as(diploid) germ cell

Female one egg per Males produce 4 sperm

germ cell per germ cell

EGG(n) SPERM(n)

2.Fertilization

Result of copulation,se

mencontaining

sperms ejaculated

into vagina.

Then this sperm travel

through female’s vagina

through cervix and uterus to meet mature

egg.

Although male can

release 200-300 milionsperm,but

only one can penetrate the

egg.

After fertilization in

female’s fallopian tube,thenuclei of

sperm and egg form the

zygote.

3.Cleavage

• A cleavage furrow is formed as the egg divides into numerous smaller cell called blastomeres.

• Cleavage increases the number of cells but not the overall volume of the egg.

Early cleavage(2-16cells) late cleavage

( more than 16 cells)

4.Blastula

“hollow ball of cells”

Blastomeres surround a fluid-filled cavity called a blastocoel

5.Gastrulation

• Cellular organization, invagination

• Cells become arranged into different germ layers.

• A)Ectoderm outermost layer

• B)Mesoderm middle layer

• C)Endoderm innermost layer

• CELL DIFFERENTIATION

6.Morphogenesis

Embryos may develpo in several ways

A) Oviparous -young develop outside of

mother

- feed of egg yolk

- hatch from egg

~Amniotic eggs have fluid-filled sac to protect embyro

~Some eggs encased in hard outer shell

b)Ovoviviparous -egg contained inside female

-”hatch” from egg within uterus

c)Viviparous -young develop inside he mother

-nourished directly by mother’s tissue

(placenta)

-mammals