Spermatogenesis and fertilisation

Question 1

Is phase 4 of spermatogenesis more or less rapid than oogenesis

Answer 1

More rapid

Question 2

Where does spermatogenesis begin?

Answer 2

Seminiferous tubules of testers after puberty

Question 3

What are type A spermatogonia?

Answer 3

mitotically active throughout reproductive life

Question 4

How are spermatogonia kept at edge of semiferous epithelium?

Answer 4

Interlocking sertoli cells connected by intercellular cytoplasmic bridges

Question 5

What are type B spermatogonia termed as when they enter meiosis

Answer 5

Primary spermatocytes

Question 6

How long do spermatocytes take to complete meiosis 1

Answer 6

24 days

Question 7

What happens during meiosis 1

Answer 7

spend this time making mRNA for later protein production

Question 8

What is the result of early translation into protein

Answer 8

Sterility

Question 9

What is produced from meiosis 1

Answer 9

Secondary spermatocytes

Question 10

What is produced from meiosis 2

Answer 10

Spermatids

Question 11

How are spermatids converted to spermatozoa

Answer 11

Spermiogenesis

Question 12

How does spermatid changes as it becomes spermatozoa

Answer 12

• Reduction in nuclear size
• Golgi apparatus condense
• Flagellum grows from centriole
• Cytoplasm streams away from nucleus
• Mitochondria in spiral arrangement around flagellum
• Head partitioned into domains

Question 13

What is the final step of sperm maturation

Answer 13

Capacitation

Question 14

Where does capacitation occur

Answer 14

Female genital tract (requires contact with secretions of the oviduct)

Question 15

What does LH stimulate

Answer 15

Testosterone production by Leydig cells

Question 16

What are the main targets of testosterones and FSH

Answer 16

Sertoli cells which secrete androgen binding fluids

Question 17

What do androgen binding fluids do

Answer 17

Binds to testosterone and carries to seminiferous tubule: stimulates spermatogenesis

Question 18

Where is sperm deposited?

Answer 18

Cervical ovarian sphincter

Question 19

What propels the sperm up the uterine canal?

Answer 19

Uterine cilia

Sperms propulsion

Question 20

Describe the steps of the acrosome reaction

Answer 20

• Sperm fuses with overlying plasma membrane
• Enzyme released allow passage through zona pellucida
• Finishes jounry between zp and oocyte (oolemma)
• Sperm becomes enveloped
• Fusion
• Large increase in intracellular cacium forms wave across the egg

Question 21

How does fusion occur

Answer 21

• Binds with egg receptors once acrosome reaction complete
• Cortical vesicle fuses with plasma membrane undergo exocytosis
• Releases contents into peri-vitelline spae
• Modified fertilisation detaches and rises
• Sperm pulled into egg by fertilisation cone
• Microtubules from the centrosome associated w male pronucleus
• Fuses with female pro nucleus

Question 22

How do mature egg and sperm finding each other

Answer 22

Chemotaxis

Question 23

How do cells with each other in a species specific way

Answer 23

In mammals there is a glycoprotein called ZP3 found in zona pellucida
Capacitated sperm are species specific in their binding to ZP3
Binding triggers changes in calcium and pH in sperm

Question 24

How is number of cell fusing restricted

Answer 24

Production of second messenger on sperm/ egg binding triggers blocking
Calcium wave triggers cortical release and activation of cell division

Question 25

What happens at 16-32

Answer 25

Polarisation of 2 cell populations

Outer cells form trophoblast precursors and inner cell are pluriblast (morula)

Question 26

What happens at 32-64 cell stage

Answer 26

This is blastocyst

Has to hatch off the hardened zona pellucida

Question 27

What attach itself to uterine wall

Answer 27

7-9 days post ovulation