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Questions and Answers
What is the purpose of spermatogonia in the seminiferous tubule?
What is the purpose of spermatogonia in the seminiferous tubule?
What is the ploidy of primary spermatocytes?
What is the ploidy of primary spermatocytes?
What is the result of meiosis I in spermatogenesis?
What is the result of meiosis I in spermatogenesis?
How many chromosomes are present in each secondary spermatocyte?
How many chromosomes are present in each secondary spermatocyte?
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What occurs in meiosis II in spermatogenesis?
What occurs in meiosis II in spermatogenesis?
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What hormone do hypothalamic neurosecretory cells increase their secretion of at puberty?
What hormone do hypothalamic neurosecretory cells increase their secretion of at puberty?
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What is the final stage of spermatogenesis?
What is the final stage of spermatogenesis?
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What is the principal androgen synthesized from cholesterol in the testes?
What is the principal androgen synthesized from cholesterol in the testes?
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What is the result of spermiogenesis?
What is the result of spermiogenesis?
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What pushes sperm along their way in the seminiferous tubule?
What pushes sperm along their way in the seminiferous tubule?
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What is the effect of testosterone on LH secretion by anterior pituitary gonadotrophs?
What is the effect of testosterone on LH secretion by anterior pituitary gonadotrophs?
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What is the role of inhibin in the testes?
What is the role of inhibin in the testes?
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What is the effect of FSH on spermatogenesis?
What is the effect of FSH on spermatogenesis?
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What is the role of androgen receptors in target cells?
What is the role of androgen receptors in target cells?
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What stimulates the male pattern of development of reproductive system ducts and the descent of the testes before birth?
What stimulates the male pattern of development of reproductive system ducts and the descent of the testes before birth?
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Where are Leydig cells located in the testes?
Where are Leydig cells located in the testes?
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What is the primary function of dihydrotestosterone in the development of male sexual characteristics?
What is the primary function of dihydrotestosterone in the development of male sexual characteristics?
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What is the role of androgens in male sexual behavior?
What is the role of androgens in male sexual behavior?
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What is the main source of androgens in females?
What is the main source of androgens in females?
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What is the effect of increased testosterone concentration in the blood on the release of GnRH?
What is the effect of increased testosterone concentration in the blood on the release of GnRH?
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What is the result of less stimulation by LH on the Leydig cells in the testes?
What is the result of less stimulation by LH on the Leydig cells in the testes?
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What is the role of androgens in the body?
What is the role of androgens in the body?
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What is the process called when a male gamete unites with a female gamete?
What is the process called when a male gamete unites with a female gamete?
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What is the role of the Sertoli cells in the seminiferous tubules?
What is the role of the Sertoli cells in the seminiferous tubules?
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How many days does spermatogenesis take in humans?
How many days does spermatogenesis take in humans?
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What is the function of the duct system in the male reproductive system?
What is the function of the duct system in the male reproductive system?
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What is the number of chromosomes in the spermatogonia?
What is the number of chromosomes in the spermatogonia?
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What is the term for the process by which organisms produce offspring by making germ cells called gametes?
What is the term for the process by which organisms produce offspring by making germ cells called gametes?
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What are the types of cells found in the seminiferous tubules?
What are the types of cells found in the seminiferous tubules?
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What is the function of the testes in the male reproductive system?
What is the function of the testes in the male reproductive system?
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Study Notes
Sexual Reproduction
- Sexual reproduction is the process by which organisms produce offspring by making germ cells called gametes.
- The male gamete (sperm cell) unites with the female gamete (secondary oocyte) in an event called fertilization.
- The resulting cell contains one set of chromosomes from each parent.
The Reproductive Systems
- The male and female reproductive organs work together to produce offspring.
- The organs of the male reproductive system include:
- Testes (male gonads)
- System of ducts (including epididymis, ductus deferens, ejaculatory ducts, and urethra)
- Accessory sex glands (seminal vesicles, prostate, and bulbourethral glands)
- Several supporting structures, including the scrotum and the penis
Spermatogenesis
- Spermatogenesis is the process by which the seminiferous tubules of the testes produce sperm.
- In humans, spermatogenesis takes 65-75 days.
- Spermatogenesis begins with spermatogonia, which contain the diploid (2n) number of chromosomes.
- Spermatogonia undergo mitosis, and then differentiate into primary spermatocytes.
- Primary spermatocytes undergo meiosis I, resulting in two cells with 23 chromosomes (haploid number).
- Each secondary spermatocyte then undergoes meiosis II, resulting in four haploid cells called spermatids.
- The final stage of spermatogenesis is spermiogenesis, where haploid spermatids develop into sperm.
Hormonal Control of the Testes
- Hypothalamic neurosecretory cells increase their secretion of gonadotropin-releasing hormone (GnRH) at puberty.
- GnRH stimulates gonadotrophs in the anterior pituitary to increase their secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
- LH stimulates Leydig cells to secrete testosterone, which is the principal androgen.
- Testosterone suppresses secretion of LH by anterior pituitary gonadotrophs and GnRH by hypothalamic neurosecretory cells.
- FSH acts indirectly to stimulate spermatogenesis, and synergistically with testosterone to stimulate secretion of androgen-binding protein (ABP) by Sertoli cells.
- Sertoli cells release inhibin, which inhibits FSH secretion by the anterior pituitary.
Testosterone
- Testosterone is synthesized from cholesterol in the testes and is the principal androgen.
- Testosterone stimulates the male pattern of development of reproductive system ducts and the descent of the testes before birth.
- Testosterone and dihydrotestosterone bring about development and enlargement of the male sex organs and the development of masculine secondary sexual characteristics at puberty.
- Androgens contribute to male sexual behavior, spermatogenesis, and sex drive (libido) in both males and females.
- Androgens are anabolic hormones, stimulating protein synthesis.
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Description
This quiz covers the basics of sexual reproduction, including the process of fertilization and the resulting cell. It's based on Lecture 5 by Biologist Mohammed Sarim AL.Fatli.
