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Sem 4 > Repro 1: Development Of Reproductive Systems > Flashcards

Repro 1: Development Of Reproductive Systems Flashcards

1
Q

In males, Sertoli cells express which gene?

A

The SRY gene (on the Y chromosome)

This drives development of the make gonad, internal genatalia, and external genitalia

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2
Q

Male internal genitalia is formed by…

A

Mesonephric ducts aka Wolffian duct

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3
Q

Female internal genitalia is formed by…

A

Paramesonephric ducts (aka Müllerian ducts)

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4
Q

In males, how do the Müllerian ducts regress?

A

Sertoli cells secret MIH (müllerian inhibitory hormone) and interstitial cells secrete testosterone
Hence, Müllerian ducts regress and Wolffian ducts develop

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5
Q

If there were no gonads at all, which ducts would develop?

A

Müllerian ducts

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6
Q

In female, what do the urethral folds and genital swellings form?

A

Genital folds form labia minora

Genital swellings forms labia majora

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7
Q

In females, what does the gentian tubercle form?

A

Clitoris

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8
Q

In males, what does the gentian tubercle form?

A

Glans penis

Forms under stimulation from androgens, unlike female genitalia which forms without hormonal stimulation

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9
Q

In males, what do the genital folds form?

A

They fuse to form spongy urethra and shaft of the penis

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10
Q

In males, what do the genital swellings forms?

A

They fuse to form the scrotum

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11
Q

Before the testes descend, what attaches them to the future scrotum?

A

Gubernaculum

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12
Q

Failure of what to obliterate in males will cause an indirect inguinal hernia?

A

Failure of processes vaginalis to obliterate

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13
Q

What is the fascial layer that covers the testes as they descend?

A

Processus vaginalis

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14
Q

What is the remnant of the gubernaculum in men?

A

Scrotal ligament

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15
Q

In females, the gubernaculum attaches the ovaries to the labioscrotal folds. What does the gubernaculum later become?

A

The ovarian ligament, attaching the ovaries to the uterus

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16
Q

What is the only structure occupying the inguinal canal in females?

A

Round ligament of the uterus (attaching uterus to labia)

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17
Q

What are some characteristics of Turners syndrome (45,XO)?

A

Short stature
Primary amenorrhoea
Failure of secondary sexual characteristics eg breasts

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18
Q

What do Leydig cells secrete?

A

Androgens, mainly testosterone

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19
Q

Where do spermatozoa develop?

A

In seminiferous tubules, in association with Sertoli cells

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20
Q

Initially, spermatogonia divide by mitosis to give rise to which 2 cell types?

A

Type A spermatogonia which are stem cells to maintain the stock
Type b spermatogonia which are committed to differentiation to produce primary spermatocytes

21
Q

What happens to the primary spermatocytes in spermATOgenesis?

A

They undergo meiosis to form 2 haploid spermatocytes

These divide again to form 4 primary spermatids

22
Q

What happens in spermIOgenesis?

A

The spermatids differentiate into spermatozoa. Cytoplasmic bridges break down and the sperm is released into the lumen

23
Q

What structures do sperm pass down as they are produced?

A

Seminiferous tubules -> rete testis -> ductuli efferentes -> epididymis -> vas deferens -> urethra

24
Q

What is the point in the blood testes barrier?

A

To stop the immune system getting access to the spermatozoa

25
Q

What is the spermatogenic cycle and how long is it in humans?

A

The time taken for the reappearance of the same stage of spermatogenesis within a given segment of a seminiferous tubule.
16 days approx in humans

26
Q

What is the spermatogenic wave?

A

The distance between the same stage of spermatogenesis along the tubule.

27
Q

Sperm is composed of secretions from where?

A

Approx 70% is seminal vesicle secretions
Approx 25% is prostate secretions
2-5% is sperm
Approx 1% is bulbourethral gland secretions

28
Q

What is sperm capacitation?

A

For sperm to become fertile, female genital tract condition stimulate the removal of glycoproteins and cholesterol from sperm membrane and the activation of signalling pathways
Allows sperm to bind to oocyte zona pellucida

29
Q

What are primordial follicles?

A

Primary oocytes (arrested in prophase of meiosis 1) that are surrounded by flat epithelial follicular cells

30
Q

After puberty a number of oocytes undergo which three stages each month in order to form a mature gamete?

A

1 pre-antral
2 antral
3 pre-ovulatory

31
Q

What occurs in the pre-antral stage?

A

The primordial follicle grows, and the surrounding follicular cells change from flat to cuboidal and proliferate to forms stratified layer of granulosa cells
Granulosa cells secrete glycoprotein to form the zona pellucida
Surrounding stromal (connective tissue) cells form the theca interna (vascular and endocrine) and the theca externa (fibrous capsule)
Theca and granulosa cells secrete oestrogens

32
Q

What occurs in the antral stage?

A

Fluid filled spaces appear between the granulosa cells forming an antrum
LH binds to theca cells to produce androgens
FSH binds to granulosa cells to convert the androgens to oestrogens

33
Q

What happens in the pre-ovulatory stage?

A

Receptors for LH appear of granulosa cells
LH surge stimulates the oocyte to resume meiosis
Meiosis 1 proceeds (asymmetrically, forms one daughter cell and one polar body) but meiosis 2 arrests in metaphase and doesn’t complete unless the oocyte is fertilised

34
Q

If there is no fertilisation, how long does the corpus luteum live for?

A

14 days

35
Q

How is the corpus luteum formed?

A

After the follicle ruptures in ovulation, the LH surge triggers lutenisation of the remains of the follicle to form the corpus luteum

36
Q

What happens to the corpus luteum if there is fertilisation of the oocyte?

A

hCG ensures the CL persists and it secretes progesterone until approx 4 months, when the placenta can take over

37
Q

What happens to the CL if there is no fertilisation?

A

CL degenerates. Forming fibrous scar tissue (corpus albicans)
Progesterone production decreases as CL degenerates which triggers menstrual bleeding

38
Q

What are the gonads developed from?

A

Intermediate mesoderm and primordial germ cells

39
Q

What does the absence of the SRY gene lead to?

A

Formation of female internal and external genitalia

40
Q

How does the mesonephric duct regress in female embryos?

A

Due to the absence of testes producing androgens, the mesonephric duct can not be maintained

41
Q

How does the paramesonephric duct degenerate in males?

A

Due to MIH released from the testes

In females it is the lack of MIH that supports development of the paramesonephric ducts

42
Q

What drives the formation of male external genatalia?

A

DHT (dihydrotestosterone) from the testes

(The absence of DHT in females prevents fusion externally, hence the urethra opens at the anterior urogenital sinus, and the vagina posteriorly)

43
Q

Which cells form the blood testes barrier?

A

Sertoli cells

44
Q

What is the function of the blood testes barrier?

A

To prevent hormones and constituents of systemic circulation from affecting developing sperm
Also to prevent the immune system of the male recognising the sperm as foreign (as they are genetically different so would possess different antigens)

45
Q

What is spermiation?

A

When the cytoplasmic bridges between the primary spermatocytes break down and the spermatids are released into the lumen of the seminiferous tubule

46
Q

How long does spermatogenesis take?

A

Approximately 70 days

47
Q

When do spermatogenesis and oogenesis begin?

A

Oogenesis begins in the foetus before birth (a female human is born with approx 2 million primary oocytes arrested in prophase of meiosis I)
Spermatogenesis only begins when males begin puberty

48
Q

What are the cells that are produced as a result of meiosis I in spermatogenesis called?

A

Secondary spermatocyte

Sem 4 (25 decks)

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