Spermatogenesis and Oogenesis Pgs 984 985 Campbell Spermatogenesis

Spermatogenesis and Oogenesis Pgs. 984 -985 (Campbell)

Spermatogenesis • Production of sperm – Continuous and prolific – Each ejaculation contains ~100 -650 million sperm • Occurs in the testes – Seminiferous tubules

What happens is … • Spermatogonia (stem cells that give rise to sperm) are located at the periphery of each seminiferous tubule – Spermatogonia are diploid • Developing sperm move toward the central opening (lumen) of the tubule as they undergo meiosis and differentiation • 4 cells result – Develop into mature sperm – Haploid

Pg. 985 Campbell Page 985 Campbell

The structure of sperm Campbell

Oogenesis • The development of ova – Mature, unfertilized eggs cells – Happens in the ovary • Oogonia (stem cells that give rise to ova) – – Multiply and begin meiosis STOPS at prophase 1 At this phase, the cells are called primary oocytes Remain in this phase until the onset of puberty, when they are activated by hormones • Activated by LH and FSH

What happens next. . . • Beginning at puberty, FSH periodically stimulates a follicle to grow and induces its primary oocyte to complete meiosis 1 and start meiosis 2 • Meiosis then STOPS again – The secondary oocyte, released during ovulation, does not continue meiosis right away – Penetration of the egg cell by sperm triggers the completion of meiosis – Then meiosis is complete – LH stimulates the completion of meiosis

Campbell Growing follicle

Major difference #1 • 1. unevenness in the mitotic division/cytokinesis of oogenesis – Almost all the cytoplasm 1 daughter cell (secondary oocyte) – 3 polar bodies which degenerate – Spermatogenesis = four mature sperm

Major difference #2 The cells that produce sperm continue to divide by mitosis throughout life (males) Not the case for women *born with all the primary oocytes

Major difference #3 • Oogenesis has long resting periods • Sperm is produced in an uninterrupted sequence

Exit Slip • On the slip of paper, write a proper heading and title it Exit Slip 4/14/09 • Answer the following questions in complete sentences: – 1. When (during the menstrual cycle) does the production of the hormones FSH and LH peak? – 2. Arrange the following organs in the correct sequence for the travel of sperm: epididymis, testis, urethra, vas deferenes – 3. List one function/role for the following hormones: • Testosterone • Estrogen • FSH