First Week of Development

Question 1

Where does fertilization occur?

Answer 1

the ampulla of the uterine tube

Question 2

When can a sperm fertilize an egg?

Answer 2

only after undergoing capacitation and acrosome reaction

Question 3

Capacitation

Answer 3

period of conditioning that takes place in female reproductive tract lasting 7 hours

Question 4

Acrosome reaction

Answer 4

induced by zona proteins after the sperm binds to the zona pellucida, this process releases enzymes that allow the sperm to penetrate the zona pellucida

Question 5

How many phases does fertilization have?

Answer 5

6 phases

Question 6

Phase 1 of fertilization

Answer 6

passage of sperm through the corona radiate of the oocyte

Question 7

Phase 2 of fertilization

Answer 7

penetration of the zona pellucida, the release of acrosomal enzymes allows the sperm to penetrate the zona pellucida and come in contact with the plasma membrane of the oocyte

Question 8

Phase 3 of fertilization

Answer 8

fusion of the plasma cell membranes of the oocyte and sperm, sperm head and tail enter the oocyte

Question 9

Phase 4 of fertilization

Answer 9

completion of the second meiotic division of the oocyte- forms the female pronucleus and the second polar body

Question 10

Phase 5 of fertilization

Answer 10

formation of the male pronucleus- the tail degenerates and the nucleus of the sperm enlarges, DNA replication occurs

Question 11

Phase 6 of fertilization

Answer 11

breakdown of the pronuclear membranes and restoration of diploid number of chromosomes

Question 12

Cleavage

Answer 12

division of the zygote begins approx. 30 hours after fertilization

Question 13

What are the cells that become smaller during mitotic division of the zygote called?

Answer 13

balstomeres

Question 14

Morula

Answer 14

the 16 to 32 cell stage

Question 15

Blastocyst formation

Answer 15

around day 4 the morula enters the uterus, uterine fluid penetrates through the zona pellucida to the intercelluar space of the inner cell mass, the fluid filled space is called the blastocystic cavity

Question 16

Blastomeres are seperated into two parts

Answer 16

Inner cell mass is the embroblast that gives rise to the embryo proper, and the outer cell mass or tropoblast that forms the placenta

Question 17

When does implantation occur?

Answer 17

6 days after fertilization