Endo-Repro L12 Male 1 Flashcards Preview

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Flashcards in Endo-Repro L12 Male 1 Deck (32):
1

Seminiferous Tubule

Containing Sertoli cells and germ cells.
Encircled by myoid cells

2

Sertoli cells

Somatic cell lining tubule. Nurse cell required for spermatogenesis
Regulated by FSH

3

Myoid cells

Move sperm along tube by peristalsis

4

Interstilal Area

Containing Leydig cells, Lymph vessels and macrophages.

5

Leydig cells

Produces testosterone under control of LH

6

Spematagonia lie on

The BM → as they mature they move towards the lumen.

7

Sertoli functions

Testosterone binds to androgen binding protein mad eby the cell and provides:
1. Physical support
2. Metabolic support (controls migration)
3. Secretes testicular fluid and maintains it

8

Blood testis barrier

Meiosis occurring and so is protective

9

Spermogenesis

Spermatids to spermatozoon.

10

Vascular compartment

Blood vessels

11

Interstitial compartment

Leydig cells, macrophages

12

Basal compartment

Sertoli cells and germ cells below the level of the blood-testis barrier (tubule itself)

13

Adluminal compartment

Sertoli cells and germ cells above the level of the blood-testis barrier (post meiotic cells and more mature.

14

Purpose of Blood-Testis Barrier: (2)

1. Maintains differences in fluid composition between fluid within tubule and outside tubule.
a. Spermatogeneisis requires particular environment
2. Protects developing sperm from auto-immune attack.

15

IgM attacks

Acrosome

16

IgG/IgA

Attacks head

17

IgM

Attacks bottom of head

18

Tubular Fluid:

1. Milieu for developing germ cells and vehicle for sperm transport
2. First produced at sexual maturation ie puberty
3. Blood-testis barrier must be present
4. Fluid is secreted and maintained by Sertoli cells
a. Regulate passage of ions, selective flow of water, steroids and carbohydrates into tubular lumen

19

Testicular Steroid Production:
4 classes:

1. Progesterones
2. Androgens
3. Oestrogens
4. Corticosteroids

20

Testicular Androgen Synthesis:

1. LH binds to the leydig cell which converts cholesterol to
a. Progesterone → delta 4 pathway leading to testosterone production
b. Androstenediol → delta 5 pathway leading to testosterone production

21

2. Testosterone can either go:

a. To blood and lymph (male repro tract and accessory organs)
b. Sertoli cell
i. Testosterone converted to DHT via 5 alpha reductase.

22

i. Testosterone converted to DHT via

5 alpha reductase.

23

Testicular Oestrogen Synthesis:

• LH initiates testosterone production, which is moved to the sertoli cell
• Aromatase converts testosterone to oestradiol 17beta and the transported into blood and lymph

24

Other Hormones produced by the testis:
Oestrogens: how

1. Produced by conversion of testosterone via AROMATASE.
2. Produced locally and by peripheral conversion of androgen.

25

oestrogen role

3. Actions unclear but essential for male fertility and spermatogenesis.
4. Important role in fluid reabsorption by the proximal epididymis.
5. Important for development and maturation of male reproductive tract.

26

Functions of Testosterone: (9)

1. Sex differentiation, growth and development of male genitalia
2. Induce secondary sex characteristics (deep voice, beard, body form, penile growth etc)
3. Support spermatogenesis
4. Induce and maintain accessory sex glands
5. Growth and fusion of long bones
6. Muscle development
7. Metabolic and cardiovascular effects
8. Libido and behavioural effects (males and females)
9. Regulate secretion of LH

27

Hypothalamic control of gonadotrophin release

1. Pituitary produces luteinising hormone (LH) and follicle stimulating hormone (FSH)
2. Control is by GnRH (pulsatile release 1-3 pulses.h)
3. LH targets Leydig cells
4. Testosterone feedback at pituitary and hypothalalmus (only on LH). Oestrdiol?
5. Levels of LH and testosterone oscillate hour by hour.

28

6. Changes in LH or FSH output by

a. Alteration of GnRH release
b. Alteration in GnRH sensitivity of gonadotrophs

29

Testosterone often acts through →

conversion to DHT by 5 alpha reductase enzyme.

30

Factors affecting LH and testosterone levels:

1. Gonadectomy
2. Androgen administration
3. Diurnal rhythm (small effect)
4. Illness or stress
5. Sexual activity
6. Age
7. Endocrine disorders

31

Congenital enzyme deficiency: inherited 5-alpha reductase deficiency

1. Wolffian duct differentiation
2. Virilisation of external genitalia

32

Androgen insensitivity syndrome (testicular Feminisation Syndrome)

1. Caused by lack of functional testosterone receptors
2. Is XY with testis
3. No internal tract, female phenotype (genitalia and secondary sex characteristics)
4. Can be partial or complete

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