What is this?

Homunculus A sperm cell with a tiny human in it 1678 – Leeuwenhoeck – each sperm contained a tiny preformed animal only needed nourishment of the female’s womb to grow

Fertilization http://www.youtube.com/watch?v=6CBBzw6xUJE http://www.youtube.com/watch?v=YYqnqr8X-Nw&feature=related http://www.youtube.com/watch?v=09kLIsNfaO8&NR=1 https://www.youtube.com/watch?v=_5OvgQW6FG4

– the union of sperm and egg nuclei Fertilization membrane nuclei egg cytoplasm A Fertilized Egg Fertilization – the union of sperm and egg nuclei

Zygote (fertilized egg)

Cleavage http://www.youtube.com/watch?v=w_ydqBzVe9g Sand dollar cleavage http://www.youtube.com/watch?v=GO5YN_t1fqw Xenopus cleavage - awesome

embryo 2 cells

Embryo 4 cells

Cleavage In a fertilized egg, the series of cell divisions that occur without growth Continues until the cells of the embryo are reduced to the size of the cells of the adult organism

Twins Identical Fraternal 2 different eggs fertilized by 2 different sperm 1 egg fertilized by one sperm; embryo splits into two embryos

Siamese Twins http://www.youtube.com/watch?v=BcC_qaqRTBA&feature=related http://www.youtube.com/watch?v=K57IcN9DWXo

Siamese twins

Cleavage to Implantation http://www.youtube.com/watch?v=raDDvuSfbhY

16 cell embryo

morula Solid ball of cells

Morula

Hollow center filled with fluid blastula Hollow center filled with fluid

trophoblast Inner cell mass

Blastocyst

When does pregnancy begin? pregnancy begins with implantation implantation - the fastening of the embryo to the endometrium (wall of the uterus)

trophoblast (outer layer of cells of blastula) develops into the chorion - secretes HCG human chorionic gonadotropin

Sperm penetrates egg Sperm gets to egg zygote Fertilization sperm membrane egg 8 cells 16 cells 2 cells 4 cells solid ball of cells (morula)

solid ball of cells (morula) hollow ball of cells (blastula)

http://www.luc.edu/depts/biology/dev/urchgast.htm

Gastrulation http://www.youtube.com/watch?v=8v6cXkzlEQA&feature=related

D gastrula gastrula solid ball of cells (morula) Hollow (blastula) ectoderm gastrulation endoderm mesoderm tadpole

gastrula gastrulation ectoderm endoderm mesoderm

Stage of embryonic development in which the germ layers are formed Gastrula Stage of embryonic development in which the germ layers are formed Germ layers give rise to all the tissues and organs of animals

Differentiation the series of changes that transforms unspecialized embryonic cells into specialized cells, tissues, and organs that make up the adult organism

What is differentiation? The process in which unspecialized cells become specialized cells

If every cell in the body has the entire genome in its nucleus (in other words each cell has all the same genes), then what makes cells become specialized?

Differential gene expression Some Genes are expressed only in certain cells. ex. gene for pepsin is only active in certain stomach cells

What is gene expression? When a gene is activated and is making the polypeptide it codes for.

Germ Layers Endoderm Mesoderm Ectoderm lining of digestive tract and respiratory system, liver, pancreas, urinary bladder dermis musculoskeletal system circulatory system reproductive organs, excretory system epidermis nervous system

The process in which sperm and egg nuclei fuse ___________________. 2. The structure which prevents more than one sperm from entering the egg_________________________. 3. The cell divisions (without growth) which the fertilized egg goes through ___________________. 4. The kind of cell division (nuclear division) occurring throughout the development of the embryo is ______________. fertilization Fertilization membrane cleavage mitosis

5. The ectoderm, mesoderm, and endoderm are called ___________________. 6. The ectoderm, mesoderm, and endoderm give rise to all the structures in the fully developed animal. The specialization of cells during this process of development is called____________________. 7. During cleavage, the number of cells _______________________. 8. During cleavage, the size of cells _______________________. Germ layers differentiation increases decreases

A tiny fish, the embryo is formed The three-layered stage develops to form organs Stages having 2 and then 3 layers of cells develop A hollow ball, made of a single layer of cells, develop The 4, 8, 16, 32, 64, and 128 cell stages develop The fertilized egg divides into 2 cells

Place these events in the right order Implantation Differentiation Fertilization Formation of organs Ovulation Gastrulation Cleavage Formation of placenta

Ovulation Fertilization Cleavage Implantation Formation of placenta Gastrulation Differentiation Formation of organs

Sperm + egg Fertilization Zygote Cleavage 2 celled 4 celled etc. More cleavage Morula More cleavage Blastula (blastocyst) Hatches Implantation Gastrulation and cleavage Gastrula (germ layers)

http://www.luc.edu/depts/biology/dev/urchgast.htm

ectoderm mesoderm endoderm Gastrula

Embryo to fetus http://www.youtube.com/watch?v=HBBNu_dAGhs&feature=related

Each cell in a human embryo has the same genetic material (DNA), yet some cells become heart cells, other cells become brain cells, and others will develop into kidney cells (etc…) How do the many different kinds of cells in the body develop if they have the same DNA?

Review: Trace the path of sperm from where it is produced to where it fertilizes the egg. List all the structures it travels through to get to the egg.

Testes Epididymis Vas Deferens Urethra (penis) Vagina Cervix Uterus Oviduct

Fetal membranes (extraembryonic membranes) amnion yolk sac allantois chorion

http://www.youtube.com/watch?v=LKvez9duEHQ http://www.youtube.com/watch?v=tof5b1Qs_OE&feature=related

amniotic fluid chorion allantois Chicken embryo airspace shell yolk sac albumin yolk

amnion thin, tough, membranous sac that encloses the embryo or fetus of a mammal, bird, or reptile. It is filled with amniotic fluid in which the embryo is suspended

Yolk sac birds – stores yolk (food) humans - blood cell formation has no yolk

Allantois - forms primitive urinary. bladder; becomes blood Allantois - forms primitive urinary bladder; becomes blood vessels on embryonic side of placenta; allantoic stalk becomes part of umbilical cord (yolk sac and allantois become the umbilical cord)

chorion – membrane surrounding embryo and other extra-embryonic membranes; chorionic villi - projections of chorion containing blood vessels; project into maternal pools of blood chorionic villi and uterine lining become the placenta

chorion

              

Who has a larger egg cell, an elephant or a chicken?

           Animal Internal Fertilization External Fertilization Internal Development External Development Amphibians Reptiles Birds Mammals nonplacentals placentals           

3 11 6 9 5 1 2 8 4 7 10

How could a man become pregnant?

http://health.howstuffworks.com/adam-200109.htm placenta http://www.youtube.com/watch?v=gHnFoWEVs7o http://health.howstuffworks.com/adam-200109.htm placenta

Placenta Fetus Uterus Umbilical Cord Amniotic Fluid Amniotic Sac (Amnion)

Umbilical Vein Umbilical Artery Placenta Chorionic Villus Fetal Capillary

placenta A temporary organ (gland) forming from the chorion and the endometrium from mother What are the functions of the placenta?

1. source of nourishment for embryo Functions of the Placenta 1. source of nourishment for embryo 2. respiratory surface for embryo 3. excretory organ of embryo 4. attaches embryo/fetus to wall of uterus 5. secretes chorionic gonadotropin, progesterone, estrogen - regulation of pregnancy

The blood of the embryo/fetus and the mother do not mix! (embryonic and maternal circulatory systems are not connected ) How do substances get for the mom’s blood to the fetus and vice versa?

Substances diffusing through the placenta From mom to embryo/fetus Oxygen Nutrients Antibodies From embryo/fetus to mom Wastes Human Chorionic Gonadotropin

Dangerous substances can pass through the placenta Viruses (e.g. measles, AIDS) Drugs (e.g. nicotine, prescription drugs) Alcohol

development http://www.youtube.com/watch?v=UgT5rUQ9EmQ&feature=related

3 weeks

4 weeks

5 weeks

6 weeks http://health.howstuffworks.com/adam-200127.htm Amniotic fluid

6 weeks

3 months

Development – series of events that give rise to a Development – series of events that give rise to a fully grown organism Mass – the amount of matter in an object Premature – a baby born before it is fully developed Fetus – the developing baby after the second month of pregnancy; has all the organs and organ systems formed Embryo - A multicellular organism in an early stage of development

Place these in the correct order: Ovulation Stage Menstruation Corpus Luteum Stage Follicle Stage

Stages of the Menstrual Cycle Follicle Stage Ovulation Corpus Luteum Stage Menstruation

What is happening to the 2 chromosomes in the middle?

Crossing Over

oviduct cleavage of embryo fertilization implantation egg moves down oviduct uterus ovulation Sperm deposited in vagina

https://www.youtube.com/watch?v=L3z_aJn-WOM&NR=1&feature=fvwp Week 7 http://www.youtube.com/user/cellmedicine?v=gCVlvq7euek&feature=pyv&ad=7945556449&kw=ms%20cure Stem cell therapy for MS