Starter1. Describe the function of each of

the following parts.

a) Testisb) Vas deferensc) Epididymisd) Seminal vesicle

Starter Testis: sperm production / testosterone

production.

Vas deferens: carry sperm from testis / epididymis to urethra / penis.

Epididymis: sperm mature here/sperm stored here.

Seminal vesicle: add sugar to sperm.

Starter The

diagram shows a section through an ovary.

1. Name and describe the process that has occurred at A.

Starter The

diagram shows a section through an ovary.

2. Name the hormone the corpus luteum produces.

3. Describe the function of this hormone.

Starter4. Explain why the testes need to

be outside the body to make healthy sperm.

5. Explain why a man must have a high sperm count if his partner is to become pregnant.

Implantation

Embryo Developme

nt

Embryo Development After fertilization the zygote

begins to divide by mitosis, first into 2 cells, then 4, then 8, etc.

Eventually a solid ballof cells, called a morula, is formed.

Embryo Development By the time the ball of cells

reaches the uterus it has developed a fluid filled cavity and is called a blastula.

Embryo Development

Blastocyst

Developing oocyte surrounded by follicle.

Released ovum with polar body.

Fusion of the sperm and ovum nucleus.

Mitotic division of the zygote.

Implantation Implantation is the

event where the blastocyst becomes buried in the lining of uterus.

The blastocyst develops villi to increase the surface area for food absorption.

Implantation Eventually these villi become

concentrated in one area (early placenta).

The Placenta The placenta

is a temporary organ that develops partly from the mother and partly from the embryo.

The Placenta The placenta has two

main functions:

1. It facilitates the transfer of substances (nutrients and wastes) between the mother and the embryo.

The Placenta Early on the corpus luteum keeps

producing oestrogen and progesterone.

2. Eventually the corpus luteum dies and it is the placenta that takes over production of these hormones that are essential in maintaining pregnancy.

The Placenta The blood of the mother and

embryo come close but never mix.

a) Mixing of blood could allow for the transfer of pathogens.

b) The mother and baby could have different blood types.

FoetalBlood

MaternalBlood

Villi Wall Capillary Wall

UreaGlucose

Amino Acids

Carbon DioxideOxygen

The Placenta The embryo is very delicate and requires

protection from potential impact.

The amnion is a membranous sac which surrounds and protects the embryo.

Within the amnion is about 1 litre of amniotic fluid that acts to cushion the embryo and allow it to move freely in the uterus.

Placenta