Gametogenesis and Spermatogenesis Control
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This document summarizes male fertility and factors that impact sperm production and delivery. It discusses the roles of the hypothalamus, pituitary gland, testes and accessory sex organs in spermatogenesis and fertilization. It also outlines factors that can negatively influence sperm quality or quantity, such as varicoceles, infections, lifestyle, and occupational or environmental exposures. Evaluation of male fertility includes medical history, physical exam, semen analysis and additional tests as needed.
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Gametogenesis and Spermatogenesis Control
- 2. Anatomy
- 6. A - Seminiferous tubules contain germ cells & Sertoli cells B – Leydig cells produce testosterone in response to LH C – Tubal Lumen
- 15. The Sperm Head Head: EM, LS × 14 000 AC = acrosome; PM = plasma membrane From Wheater’s Functional Histology, 4 th ed., 2000. The head of a mature sperm, lengthwise, is approximately 1/20 the diameter of a mature ovum.
- 16. The Sperm Neck Neck (middle piece and principal piece): EM, LS × 17 000 Mi = mitrochondria; C = cytoplasm; F, Rn, Rb, & An = all parts of flagellum structure From Wheater’s Functional Histology, 4 th ed., 2000.
- 17. Sperm Tail
- 22. Infertility Primary infertility is the inability to conceive a pregnancy, after one year of unprotected intercourse. Secondary infertility describes couples who previously conceived at least once, but have achieved another pregnancy
- 23. Estrogen-like industrial chemicals in water
- 26. From: Netter, F.H., The CIBA Collection Varicocele Defects in spermatogenesis
- 27. 39% of infertile men have a varicocele Varicocele
- 33. CONSECUTIVE SEMEN DONOR CONCENTRATIONS OVER FOUR YEARS Sperm Count Variability
- 34. Sperm Morphology
- 35. Round Cell Stain
- 41. Sperm Chromatin Structure AssaySCSA SCSA/SDFA test is a good predictor, relative to other sperm measures, for the clinical diagnosis of male infertility
- 50. L-carnitine and Acetyl-L-carnitine Human Research Findings
- 52. L-carnitine and Acetyl-L-carnitine Human Research Findings
- 56. L-carnitine and Acetyl-L-carnitine Human Research Findings
- 60. ICSI I ntra- C ytoplasmic S perm I njection
Editor's Notes
- It is not a 50/50 chance as to choosing the correct oviduct for a sperm. Sperm have a tropism for ova of their species—they are attracted toward the ovum in the correct oviduct, making species-specific fertilization and fertilization in general more likely.
- Passage of sperm: Since sperm can only move 2 to 3 mm per minute using their own power, they must be helped along somehow. At the shortest, sperms can be found in the oviducts only 5 minutes after ejaculation. Other sperms can take 45 minutes. The Natural Family Planning method of attempting pregnancy relies on changes in mucus thickness for the timing of intercourse—the character of the mucus is a good indicator of the presence of a viable egg.
- For a test to be useful, it must have a threshold above and below which it will provide discriminatory and predictive capabilities, with little overlap between fertile and infertile men. Conventional semen parameters often do not meet these standards. Although widely used thresholds for normal semen measurements have been published by the World Health Organization (WHO), [World Health Organization. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction. Singapore: Press Concern, 1980; Idem. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction. 2nd ed. Cambridge, England: Cambridge University Press, 1987; Idem. WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 3rd ed. Cambridge, England: Cambridge University Press, 1992; Idem. WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 4th ed. Cambridge, England: Cambridge University Press, 1999.] the available norms for sperm concentration, motility, and morphology fail to meet rigorous clinical, technical, and statistical standards. In recognition of these limitations, the nomenclature in the most recent WHO manual (1999) for semen evaluation was changed from “normal” to “reference” values. Recent prospective studies of semen quality and fertility concluded that the current WHO reference values should be reconsidered.
- For a test to be useful, it must have a threshold above and below which it will provide discriminatory and predictive capabilities, with little overlap between fertile and infertile men. Conventional semen parameters often do not meet these standards. Although widely used thresholds for normal semen measurements have been published by the World Health Organization (WHO), [World Health Organization. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction. Singapore: Press Concern, 1980; Idem. WHO laboratory manual for the examination of human semen and semen-cervical mucus interaction. 2nd ed. Cambridge, England: Cambridge University Press, 1987; Idem. WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 3rd ed. Cambridge, England: Cambridge University Press, 1992; Idem. WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction. 4th ed. Cambridge, England: Cambridge University Press, 1999.] the available norms for sperm concentration, motility, and morphology fail to meet rigorous clinical, technical, and statistical standards. In recognition of these limitations, the nomenclature in the most recent WHO manual (1999) for semen evaluation was changed from “normal” to “reference” values. Recent prospective studies of semen quality and fertility concluded that the current WHO reference values should be reconsidered.
- Suggests that the coefficient of variation, repeatability and statistical soundness of measures of conventional semen parameters and sperm function tests are weak. Measures of DNA fragmentation independent of standard semen measures and clearly show that motile, morphologically normal sperm may have extensive DNA fragmentation. Spermatozoa with defective DNA can fertilize an oocyte, produce high quality early stage embryos and then, in relationship to extent of DNA damage, fail in producing a successful term pregnancy. The 23 chromosomes in the sperm head are made up of chromatin, which consists of DNA and proteins. DNA packing during the transition of histone to protomine complex at spermiogenesis (late spermatid stage) Apoptosis is a major regulatory mechanism during normal spermiogenesis. Findings suggest that there may be an abortive apoptotic process which extends until late stage of spermatogenesis resulting in fragmented DNA. 3. ROS cause peroxidative damage to the perm plasma membrane and attack DNA, inducing strand breaks and other oxidative-induced DNA damage
- Suggests that the coefficient of variation, repeatability and statistical soundness of measures of conventional semen parameters and sperm function tests are weak. Measures of DNA fragmentation independent of standard semen measures and clearly show that motile, morphologically normal sperm may have extensive DNA fragmentation. Spermatozoa with defective DNA can fertilize an oocyte, produce high quality early stage embryos and then, in relationship to extent of DNA damage, fail in producing a successful term pregnancy. The 23 chromosomes in the sperm head are made up of chromatin, which consists of DNA and proteins. DNA packing during the transition of histone to protomine complex at spermiogenesis (late spermatid stage) Apoptosis is a major regulatory mechanism during normal spermiogenesis. Findings suggest that there may be an abortive apoptotic process which extends until late stage of spermatogenesis resulting in fragmented DNA. 3. ROS cause peroxidative damage to the perm plasma membrane and attack DNA, inducing strand breaks and other oxidative-induced DNA damage