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………