Sexual

Reproduction

Overview: Sexual reproduction Overview: Sexual reproduction allows for greater genetic allows for greater genetic

diversity in the hopes that at diversity in the hopes that at least some offspring will least some offspring will

survive in a changing survive in a changing environment.environment.

Girlie Parts & Jobs

Ovaries: Produce & release mature eggs.

Fallopian Tubes: carries egg to uterus, fertilization occurs here.

Uterus: Site of embryo development.

Vagina: Birth canal and site of sperm deposit.

Female Naughty Bits1.

2a.2b.

Or…oviduct 3.

4.

5.

Same Bits, different view!

See why pregnant women always have to pee?

Boy Parts & JobsTestes: Produce Sperm

Scrotum: Outer pocket of skin to keep testes cooler for ideal conditions for sperm development.

Epididymis: A collection area for sperm.

Vas Deferens: Carries sperm to the urethra (and picks up other secretions from the seminal vesicles to create semen).

Semen: a mix of sperm and nutrient containing fluid.

Male Naughty Bits

1. Testes2. Epididymis

3. Scrotum

Penis

4. Urethra

5.

Vas deferens6. 7. Seminal Vesicle

External FertilizationSperm released into environment (usually

water). Eggs released into (watery) environment.

Fertilization occurs in environment.

# of sperm released?

# of eggs released?

Ex) invertebrates, insects, fish, amphibians.

Why?

Internal Fertilization

Sperm released inside female body (vagina).

Eggs released into fallopian tubes.

Fertilization occurs in oviduct (aka?).

# of sperm released?

# of eggs released?

Ex) Reptiles, bird, mammals (humans!)

Why?

TONS!TONS!

TONS!One (or few)

Internal Fertilization:

● occurs in the upper portion of the ●a fertilized egg is called

oviductzygote

● cell division of a zygote by begins in the . 6-10 days later, the embryo implants in the ____________, where it will develop until birth.

cleavage mitos

isoviduct uterus

Fraternal: 2 eggs and 2 sperm

Identical: 1 egg + 1 sperm

In vitro: test tube fertilization

Internal V. External Development

External DevelopmentShell

Embryo

Air Sac

Yolk* (good for dipping your toast!)

Albumin (egg white)

Allantois* (for gas exchange)

* Both of these are filled with blood vessels running to and from the embryo.

ChorionAmnion

Menstrual Cycle (females only!)

FSH: Stimulates the follicle (in ovary) to produce an ovum.LH: Causes ovulation (release of ovum from

ovary)Estrogen:

Prepares the uterine lining for the embryo.

Progesterone:

Maintains the uterine lining for implantation of embryo.

ovaryfollicle

ovum

oviduct

uterus

cervix

vagina sperm

Embryonic Development

:

1. Cleavage: repeating mitosis forms a hollow ball of cells, no increase in size, just in cell number!

2. Blastula: A hollow ball of cells approximately the same size as the zygote (fertilized egg)

3. Gastrulation: One side of the blastula indents.

4. Differentiation: see next slide!

Differentiation: which cells become which structures?

Ectoderm:Ectoderm: The outer part of the gastrula becomes the nervous system and epidermis of the skin.

Mesoderm:Mesoderm: The middle of the gastrula becomes the muscles, skeleton, circulatory system, excretory system and reproductive system.

Endoderm: The inner layer becomes the lining of the digestive tract, respiratory tract and the liver and pancreas.

What’s What?

linkYouTube - Amphioxus embryonic development

(lancelet) – primitive chordate

Cool Frog Eggs!

6 weeks 12 weeks 18 weeks

24 weeks

Gestation: time fetus develops in the uterus (40 weeks for humans)

36 weeks28 weeks

Internal Development

Cervix

Placenta1.

Umbilical Cord2.

Amniotic Sac3.

Amniotic Fluid4. 5.

6. Fetus

7. Uterine Wall

Oops! Same as # ?

8.Fallopian Tube (aka?)

Bovine OvaryImmature follicles

Mature follicle

Luteal scars

Follicular cyst

Bovine Reproductive Tract:

Left ovary

Left Uterine horn

What 2 organs are below the uterus?

Cervix and vagina are out of the picture!

Pregnant horn at early gestation

Mind your own

beeswax!

Bovine Reproductive Tract

Other really weird organisms!

And now you know about the birds and the bees………