Lecture 21: Making eggs and sperm

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Questions and Answers

What triggers ovulation?

Peak in follicle-stimulating hormone (FSH)

Peak in luteinising hormone (LH) (correct)

Peak in progesterone levels

Peak in oestrogen levels

What are the two main hormones secreted by the corpus luteum?

GnRH and FSH

Testosterone and inhibin

Progesterone and a small amount of oestrogen (correct)

Oestrogen and inhibin

What happens to GnRH secretion during puberty in males?

It remains the same

It increases (correct)

It decreases

It stops

What is the result of hypothalamus maturation in males?

Reduced sensitivity to testosterone and inhibin Signup and view all the answers

What is the age range for the onset of puberty in females?

11-13 years old Signup and view all the answers

What is the effect of oestrogen and progesterone on GnRH and LH/FSH secretion before puberty in females?

Inhibits GnRH and LH/FSH secretion Signup and view all the answers

What happens to the reproductive organs during puberty in both males and females?

They increase in size Signup and view all the answers

What is the outcome of maturation of the hypothalamus in females?

Increased GnRH secretion Signup and view all the answers

What is the purpose of mitosis?

To proliferate somatic cells Signup and view all the answers

What is the main difference between mitosis and meiosis?

All of the above Signup and view all the answers

Where does fertilization normally occur?

In the uterine tube Signup and view all the answers

What is the function of the epididymis?

To mature sperm Signup and view all the answers

What is the primary function of the seminal vesicles?

To provide nutrients to sperm Signup and view all the answers

What is the function of the prostate gland?

To provide energy to sperm Signup and view all the answers

What is the function of the bulbourethral glands?

To lubricate the urethra Signup and view all the answers

What is the approximate length of the vas deferens?

45cm Signup and view all the answers

What is the composition of semen?

60% seminal vesicles, 30% prostate, 5% testes, 5% bulbourethral glands Signup and view all the answers

What is the role of Sertoli cells in the seminiferous tubules?

To nourish developing germ cells Signup and view all the answers

What is the final stage of spermatogenesis?

Differentiation of sperm cells Signup and view all the answers

Where do oocytes pause during meiosis?

Prophase I Signup and view all the answers

How many oocytes are present at birth?

400 000 Signup and view all the answers

What is the structure that surrounds the oocyte in a primary follicle?

Granulosa cells Signup and view all the answers

What is the fate of the majority of oocytes in the ovaries?

They undergo atresia Signup and view all the answers

What is the purpose of the epididymis in the male reproductive system?

To store and mature sperm cells Signup and view all the answers

What is the term for the process by which sperm cells are formed?

Spermatogenesis Signup and view all the answers

Study Notes

Cell Division

Mitosis: 4 stages, occurs in somatic cells, produces 2 diploid daughter cells, chromosome number remains the same, purpose is cellular proliferation
Meiosis: 8 stages, occurs in germ/sex cells, produces 4 haploid daughter cells, chromosome number is halved in each daughter cell, purpose is sexual proliferation

Female Reproductive System

Ovaries open into the peritoneal cavity
Fimbriae direct ovum into the uterine tube/fallopian tube/oviduct
Successful fertilization normally occurs in the first third of the uterine tube
Vagina: channel connecting to the cervix

Male Reproductive System

Testis and scrotum: contains epididymis for maturation
Vas deferens or ductus deferens: approximately 45cm long, has peristaltic movement, contains blood vessels and nerves
Urethra: channel connecting to the penis
Seminal vesicles: produce prostaglandin, stimulate motility of sperm, fructose, clotting agents
Prostate gland: produces citric acid, proteolytic enzymes
Bulbourethral (Cowper's) glands: produce mucous, alkaline fluid

Spermatogenesis

Seminiferous tubules in testes: contain germ cells, develop into spermatocytes, nourished by Sertoli cells
Spermatogonia: develop into primary spermatocytes (2n), then secondary spermatocytes (n), then spermatids (n)
Spermatid differentiation: forms head, acrosome, midpiece, and flagellum
Released into the lumen of seminiferous tubules to the epididymis for further maturation

Oogenesis

Ovaries: suspended by ligaments, contain oogonia (5 million before birth, 400,000 at birth, 300,000 at puberty)
Ovarian follicle: contains oocyte, blood vessels, lymphatic vessels, nerves
Primordial follicle: primary oocyte pauses at Prophase I
Primary follicle: layers of granulosa cells, zona pellucida
Secondary follicle: at puberty, only 400 develop fully
Ovulation: triggered by peak in luteinising hormone (LH), completes Meiosis I and pauses during early Meiosis II

Hormones in Males and Females

Before puberty: low GnRH, low LH and FSH secretion
Puberty: hypothalamus maturation, increased GnRH, LH, and FSH secretion, development of secondary characteristics

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