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Questions and Answers
What is the purpose of spermatogonia in the seminiferous tubule?
What is the ploidy of primary spermatocytes?
What is the result of meiosis I in spermatogenesis?
How many chromosomes are present in each secondary spermatocyte?
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What occurs in meiosis II in spermatogenesis?
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What hormone do hypothalamic neurosecretory cells increase their secretion of at puberty?
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What is the final stage of spermatogenesis?
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What is the principal androgen synthesized from cholesterol in the testes?
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What is the result of spermiogenesis?
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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?
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What is the role of inhibin in the testes?
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What is the effect of FSH on spermatogenesis?
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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?
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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?
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What is the role of androgens in male sexual behavior?
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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?
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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?
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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?
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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?
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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?
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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?
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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.
