Chapter 4.5: Gametogenesis

Question 1

What is known as the germ line?

Answer 1

embryonic germ cells

Question 2

Describe oogenesis

Answer 2

o The process, known as oogenesis begins when diploid germ cells in the ovary, called oogonia, multiply rapidly by mitosis and produce a large number of primary oocytes, when then undergo meiosis
o For each primary oocyte, meiosis I results in the formation of the two daughter cells that differ in size, so this division is asymmetric
 The larger of these cells, the secondary oocyte undergoes another asymmetrical division to produce a large haploid ovum and a small haploid second polar body
 The other small sister cell is known as the first polar body
o Most women release one primary oocyte per month

Question 3

Describe spermatogenesis

Answer 3

o The production of sperm, or spermatogenesis, begins in the male testes in germ cells known as spermatogonia
o Mitotic divisions of the spermatogonia produce many diploid cells, the primary spermatocytes
o Primary spermatocytes undergo a symmetrical meiosis I, producing two secondary spermatocytes, each of which undergoes a symmetrical meiosis II
o At the conclusion of meiosis, each original primary spermatocyte thus yields four equivalent haploid spermatids
o These spermatids then mature by developing a characteristic whiplike tail and by concentrating all their chromosomal material in a head, thereby becoming functional sperm

Question 4

Define gametogenesis

Answer 4

gamete formation

Question 5

What is the end product of oogenesis?

Answer 5

o The end product of egg formation in humans is a large, nutrient-rich ovum whose stored resources can sustain the early embryo