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15. Reproductive > 1. Origin of the Sexes > Flashcards

1. Origin of the Sexes Flashcards

1
Q

Describe the internal genitalia of the male.

A

Testis, epididymis, ductus deferens, seminal glands, ejaculatory ducts, prostate, bulbourethral glands.

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2
Q

Describe the external genitalia of the male.

A

Glans penis, shaft of penis, scrotum.

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3
Q

Describe the internal genitalia of the female.

A

Ovaries, uterine tubes, uterus, vagina.

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4
Q

Describe the external genitalia of the female.

A

Labia majora, labia minora, clitoris.

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5
Q

What are the reproductive hormones produced by the hypothalamus?

A

Gonadotrophin releasing hormone (GnRH), prolactin releasing hormone (PRH), prolactin inhibiting hormone (PIH).

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6
Q

What is the reproductive hormone produced by the posterior pituitary?

A

Oxytocin.

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7
Q

What are the reproductive hormones produced by the anterior pituitary?

A

Follicle stimulating hormone (FSH), luteinising hormone (LH), prolactin.

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8
Q

What are the reproductive hormones produced by the testes?

A

Testosterone, inhibin, mullerian inhibiting hormone (MIH).

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9
Q

What are the reproductive hormones produced by the ovaries?

A

Oestrogen, progesterone, inhibin.

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10
Q

What are the reproductive hormones produced by the placenta?

A

Human chorionic gonadotrophin (hCG), human placental lactogen (hPL), oestrogen, progesterone.

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11
Q

What are the testes?

A

The male gonads, paired, ovoid reproductive glands that produce spermatozoa and male hormones.

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12
Q

What is the anatomical position of the testes?

A

Suspended in the scrotum by spermatic cords.

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13
Q

What are the testes covered by?

A

Visceral layer of the tunica vaginalis, except where they attach to the epididymis and spermatic cord. Parietal layer of tunica vaginalis is adjacent to internal spermatic fascia and extends more superiorly.

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14
Q

How can the testis move freely in the scrotum?

A

Small amount of fluid between visceral and parietal layers of the tunica vaginalis.

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15
Q

What is the tunica albuginea?

A

Tough, fibrous outer surface of the testes which thickens into a ridge on its internal, posterior aspect as the mediastinum of the testis.

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16
Q

Where are sperm produced?

A

Seminiferous tubules.

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17
Q

Where do fibrous septums from the mediastinum of the testis extend to?

A

Inwards between lobules of long and highly coiled seminiferous tubules.

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18
Q

How are the seminiferous tubules and rete testis joined?

A

Straight tubules join them.

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19
Q

What is the rete testis?

A

A network of canals in the mediastinum of the testis.

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20
Q

Where are sertoli cells?

A

In the seminiferous tubule.

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21
Q

What happens at the sertoli cells?

A

Spermatozoa development.

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22
Q

Where are the leydig/interstitial cells?

A

In the interstitial tissue.

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23
Q

What do leydig/interstitial cells secrete?

A

Testosterone.

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24
Q

How are the tubules of the testis separated from surrounding interstitial tissue?

A

By the blood testis barrier.

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25
Q

How are spermatogonia stem cells formed?

A

Before birth, germ cells in the sex cords of the primordial gonad proliferate by mitosis to form them.

26
Q

How do men stay fertile till up to and over aged 70?

A

Stem cells undergo mitosis to keep regenerating stem cell throughout life.

27
Q

What happens to make a male fertile in puberty?

A

The sex cords hollow out to form the seminiferous tubules.

28
Q

How many seminiferous tubules are there?

A

250-750 per testis.

29
Q

How does the epididymis form?

A

By the seminiferous tubules emptying into rete testis.

30
Q

What is the beginning of spermatogenesis?

A

A1 spermatogonia emerge from stem cells.

31
Q

Briefly outline spermatogenesis.

A

A1 spermatogonia emerge from stem cells. They differentiate to form more type A stem cells or type B cells which become spermatozoa. These divide to form 64 clones of primary spermatocytes that are linked by cytoplasmic bridges. This chain pushes towards the lumen of the tubule and begin meiosis to form 2 haploid secondary spermatocytes after the first division, then spermatids. Become sperm by spermiogenesis as cytoplsamic bridges break down. Mature as they move through epididymis.

32
Q

Theoretically, how many spermatids can come from one A1 spermatogonium?

A

256 spermatids.

33
Q

How do the sperm move from the seminiferous tubules to the rete testis?

A

Move in fluid from Sertoli cells.

34
Q

How long does spermatogenesis take?

A

70 days.

35
Q

How is there a wave of sperm production along the tubule?

A

A1 spermatogonia arise every 16 days so there are four simultaneous cycles happening. These are along the tube so production is continuous in a wave.

36
Q

How does emission happen?

A

SANS stimulation of the vas deferens to sweep along sperm, seminal vesicle secretions, and prostatic secretions.

37
Q

What is the spermatogenic cycle length?

A

The amount of time it takes for reappearance of the same stage of the cycle within a given segment of the tube.

38
Q

What is the spermatogenic wave?

A

Different parts of the tube begin the spermatogenic cycle at different times so a wave of constant production takes place. The wave is the distance on the tube between parts that are in the same stage in the spermatogenic wave.

39
Q

What is the rete testis?

A

A network of canals in the mediastinum of the testis that seminiferous tubules drain into.

40
Q

What is the epididymis?

A

A convoluted tube, in which sperms are stored and continue to mature.

41
Q

What is the vas deferens?

A

A continuation of the epididymis with thick muscular walls and small lumen. They force sperm along tube by contracting muscles.

42
Q

What do the seminal vesicles do?

A

Secrete thick, alkaline fluid rich with fructose and coagulating agent. Makes up 60% of semen volume.

43
Q

What forms the ejaculatory duct?

A

The seminal gland joining the ductus deferens.

44
Q

What does the prostate do in semen production?

A

Makes up 20% of volume and has a role in activating sperm.

45
Q

What are the bulbourethral glands?

A

Two pea-sized glands posterolateral to the intermediate part of the urethra, embedded within the external urethral sphincter.

46
Q

Where do the bulbourethral glands open?

A

Into the proximal part of the spongy urethra in the bulb of the penis.

47
Q

What are the ovaries?

A

The female gonads, almond shaped and sized. They’re endocrine glands that produce reproductive hormones.

48
Q

Where are the ovaries?

A

Suspended by the mesovarium which is medially tethered to the uterus.

49
Q

What is the ovarian ligament a remnant of?

A

The superior part of the ovarian gubernaculum.

50
Q

What is the capsule of the ovary?

A

Connective tissue tunica albuginea.

51
Q

What is the tunica albuginea of the ovary covered with?

A

A smooth layer of ovarian mesothelium that has a dull, grey appearance.

52
Q

What scars the epithelium covering the tunica albuginea of the ovary?

A

Repeated rupture of ovarian follicle and discharge of oocytes in ovulation.

53
Q

What do uterine tubes conduct?

A

Oocyte, discharged monthly from the ovary.

54
Q

How are primordial oocytes formed before birth?

A

Primordial germ cells colonise cortex of the primordial gonad to form oogonia. These proliferate in mitosis to reach 7 million in number. But at birth there are only 2 million.

55
Q

What happens between birth and the pre-antral/primordial follicle phase?

A

The oogonia enter meiosis I to form primordial follicles. Meiosis arrests at diplotenes stage of prophase due to oocyte maturation inhibitor (OMI) from follicular cells.

56
Q

What happens in the pre-antral or primordial follicle stage?

A

The primary oocyte grows dramatically without starting meiosis. Flat follicular cells -> cuboidal granulosa cells. These secrete glycoprotein to surround oocyte as zona pellucida. Connective tissue cells form theca folliculi (inner theca interna is vascular and endocrine, outer theca externa is fibrous capsule). Theca and granulosa cells collaborate to secrete oestrogens.

57
Q

What happens in the antral or secondary follicle stage?

A

Granulosa cells continue to proliferate and fluid appears between them - antrum. The secondary follicle expands with more fluid to 2mm diametes. FSH binds granulosa cells and LH binds thecal cells to secrete androgens -> oestrogens by granulosa cells.

58
Q

What happens in the pre-ovulatory follicle stage?

A

37 hours before ovulation, ostrogen causes LH receptors to appear on outer granulosa cells so there is rapid change of follicle and it starts meiosis to complete first division - asymmetric as cytoplasm remains with one daughter cell, other forms condensed polar body. Enters meiosis II and arrests 3 hours before ovulation. Follicle size increases to 25mm diameter and structure weakens. LH stimulates follicle rupture. Ovum carries out in gluid and gathered in fallopian tube by fimbria.

59
Q

How is the corpus luteum formed?

A

Remains of follicle after pre-ovulatory follicle stage re-organise to secrete progesterone and oestrogen under LH influence.

60
Q

How long does the corpus luteum live?

A

14 days, then spontaneously regresses.

15. Reproductive (12 decks)

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