Reproductive Physiology

Question 1

What do the testis contain?

Answer 1

seminiferous tubules (sperm) and Leydig cells (testosterone)

Question 2

What is the role of the epididymis?

Answer 2

one within each scrotal sac

Sperm are stored in these and at ejaculation, sperm pass through the vas deferens (contractile) and are mixed with fluid from the seminal vesicles. The fluid then leaves the duct and passes into the urethra to mix with prostate secretions

Question 3

What regulates the male reproductive system?

Answer 3

Leydig cells – testosterone – LH stimulated

Sertoli cells – Inhibin – FSH stimulated

Question 4

What are the stages of spermatogenesis?

Answer 4

1. Germ cells - 44+XY (diploid)
   - Mitotic division
2. Primary spermatocyte - 44+XY (diploid)
   - 1st meiotic division.
3. Secondary spermatocyte - 22+X, 22+Y (haploid)
   - 2nd meiotic division.
4. Spermatids - 22+X, 22+Y (haploid).
5. Spermatozoa

Question 5

What are the organs in the female reproductive system?

Answer 5

• The ovary – produce the gametes and steroids (oestrogens and progesterone’s)
• The fallopian tubes – oviduct – sustains oocyte or conceptus
• Uterus – conceptus implants here

Question 6

What regulates the female reproductive system?

Answer 6

• Thecal cells – oestrogen and androgens – LH
• Granulosa cells – androgens -> oestradiol (produce progesterone in the second-half of the cycle) – FSH

Progestogens – maintain endometrium
Oestrogens – stimulate proliferation of the endometrium

Question 7

What are the stages of the menstrual cycle?

Answer 7

Endometrial – menstrual, repair and proliferative, secretory phases
Ovarian – follicular, luteal phase

Question 8

How does the menstrual cycle go from the proliferation phase to the secretory phase?

Answer 8

1. FSH & LH stimulate the follicular phase which results in oestradiol production -> stimulates the endometrial proliferation
2. Oestradiol (E2) production continues at a greater pace and –ve feedback switches to +ve and ovulation occurs
3. Corpus luteum produces progesterone and E2 and the endometrium enters the secretory phase

Question 9

What hormone dominates the follicular (proliferative) phase?

Answer 9

oestrogen

Question 10

What hormone dominates the luteal (secretory) phase?

Answer 10

progesterone

Question 11

When in the menstrual cycle does basal body temperature rise?

Answer 11

ovulation

Question 12

What happens to hormone levels during the menstrual cycle?

Answer 12

1. Gradual rise of oestradiol by developing follicle (FSH)
2. Follicles grow and –ve feedback on LH and FSH
3. Dominant follicle selected and produces lots of E2 -> –ve feedback switch to +ve feedback -> LH surge
4. Ovulation
5. Corpus luteum produces E2 and progesterone -> -ve feedback on LH and FSH
6. No fertilisation -> E2 and progesterone fall and endometrium enters secretory phase

Question 13

What are the stages in folliculogenesis?

Answer 13

1. Oogonia - 44+XX (diploid)
   - Mitotic division
2. Primary oocytes - 44+XX (diploid)
   - 1st meiotic division
3. Secondary oocyte (+polar body) - 22+X, 22+X (haploid)
   - 2nd meiotic division
4. Ovum (+ polar body) - 22+X, 22+X (haploid)

• 1st meiotic division is linked to the LH surge, meiosis 2 follows immediately after this BUT pauses in metaphase 2 (as shown)
• • the second polar body is generated after the 2nd meiotic division which occurs in the fertilised cell.

Question 14

Define the following :

• sexual reproduction
• sexual intercourse
• biological sex

Answer 14

Sexual reproduction – produce genetically different offspring
Sexual intercourse – required for – sexual reproduction, sexual activity, sexual pleasure, human bonding
Biological sex – identifies gender, a result of chromosomes, produces different gametes

Question 15

What happens during fertilisation?

Answer 15

1. Deposition of sperm near the cervix
   - Cervical mucous is hostile to sperm which forms a physical barrier
   - Cervical mucous changes at mid-cycle to permit sperm to enter the uterus
2. Passage of sperm through uterus and then fallopian tubes
3. Sperm moves to fallopian tube ampulla
   - Survival of the fittest
   - Capacitation takes place (within the uterus) which matures the spermatozoa
4. Egg meets sperm fusion of egg with sperm (24 hours post ovulation)
   - Acrosome reaction – penetration of zona pellucida (& Coronal cells)
   - Calcium flux
   - Resumption of meiosis, release of 2nd polar body
   - Alignment of maternal and paternal chromosomes to generate zygote
5. Change in Zona Pellucida to stop additional sperm fusing
6. Initiation of mitotic divisions in embryo.