spermatogenesis and oogenesis
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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 …. - PowerPoint PPT PresentationTRANSCRIPT
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