Male reproductive

Question 1

How does spermatozoa cell size compare to other cells?

Answer 1

They are the smallest human cell with a 3 micrometer diameter

Longest cell relative to the organism.

Question 2

What layer surrounds the testes?

Answer 2

Tough membranous shell called the tunica albuginea.

Question 3

What is the name of the fine coiled tubules within the testes?

Answer 3

Seminiferous tubules

Question 4

Where do developing sperm mature?

Answer 4

Epididymis

Question 5

Where do sperm pass from seminiferous tubule to the vas deferens?

Answer 5

Seminiferous tubule - rete testis - efferent ducts - epididymis - vas deferens

Question 6

Where do leydig cells lie?

Answer 6

Inbetween seminiferous tubules

Question 7

What do leydig cells produce?

Answer 7

Testosterone

Question 8

In the foetus what are the testis populated with

Answer 8

Spermatogonia

Question 9

When does mitosis of spermatogonia begin?

Answer 9

In foetal life

Question 10

When does spermatogenesis and meiosis beign?

Answer 10

At puberty

Question 11

What is spermatogonium?

Answer 11

Diploid stem germ cell

Question 12

What is spermatogonia?

Answer 12

Divided (mitosis) spermatogonium (still diploid)

Question 13

What is the name of the primitive sperm that undergoes meiosis I?

Answer 13

Primary spermatocyte (diploid)

Question 14

What does meiosis I produce?

Answer 14

Two haploid secondary spermatocytes

Question 15

What is the name of the primitive sperm that undergoes meiosis II?

Answer 15

Secondary spermatocytes (haploid)

Question 16

What does meiosis II produce?

Answer 16

4 round spermatids joined by cytoplasmic bridges.

Question 17

What is the benefit of cytoplasmic bridges?

Answer 17

Cytoplasmic bridges lead to synchronisation between spermatids as they allow transfer of mRNA and proteins between haploid cells

Question 18

What happens to spermatids?

Answer 18

Differentiate to form spermatozoa

Question 19

Can all haploid cells fertilise?

Answer 19

Yes

Question 20

Where do sertoli cells lie?

Answer 20

Inbetween sperm progenitors undergoing spermatogenesis

Question 21

What is the role of the sertoli cell?

Answer 21

Support spermatogenesis through secretions and phagocytosis action

Forms the blood testis barrier

Question 22

What does the sertoli cell secrete?

Answer 22

FSH
ABH (androgen binding hormone) - increases the concentration of testosterone at site of sperm development
Inhibin

Question 23

What is the blood-testis barrier, and what forms it?

Answer 23

Very tight junctions between Sertoli cells separate the basal compartment from the luminal compartment.

Question 24

What is the role of the blood-testis barrier

Answer 24

Protects sperm from the immune system

Controls the luminal environment for effective spermatogenesis

Question 25

How is DNA packing different in sperm?

Answer 25

DNA packed more tightly in sperm than somatic nuclei. Sperm: annulus repeat packed on protamines

Question 26

How long does the process of spermatogenesis take?

Answer 26

60 days

Question 27

How frequently do new cohorts of spermatogonia develop?

Answer 27

Every 12 days

Question 28

How does spermatogeneis occur through the epithelium?

Answer 28

As a wave, so adjacent parts are at a different stage

Question 29

What are the four final phases of spermatogenesis occuring at the top of the epithelium?

Answer 29

Elongation, Grouping, Maturation, Release

Question 30

How do elongation, grouping, maturation and release appear on histology slides?

Answer 30

Release - no sperm present at edge of lumen of tubule Grouping - clumpy appearance at lumen Maturation - apparent sperm at lumen

Question 31

What is spermiogenesis?

Answer 31

Spermatid maturation

Question 32

What are the three phases of spermiogenesis?

Answer 32

Golgi phase Cap phase Acrosome phase

Question 33

What happens in the golgi phase of spermiogenesis (4)?

Answer 33

Begin to develop polarity. Head forms at one end, Golgi apparatus creates enzymes that will become the acrosome. At the other end, a distal centriole begins to form an axoneme. Spermatid DNA also undergoes packaging, becoming highly condensed.

Question 34

What happens in the cap phase of spermiogenesis?

Answer 34

The Golgi apparatus surrounds the condensed nucleus, mitochondria migrate caudally. Axoneme extends

Question 35

What happens in the acrosome phase of spermiogenesis?

Answer 35

The acrosomal cap forms and mitochondria gather around the tail. Axoneme central to the flagellum

Question 36

What is the first trigger in puberty?

Answer 36

Hypothalamic kisspeptin neurons become activated

Question 37

What does kisspeptin activate?

Answer 37

Kisspeptin activates pulsatile secretion of GnRH from GnRH neurons

Question 38

What does GnRH activate?

Answer 38

Hypothalamic GnRH stimulates secretion of pituitary gonadotrophins FSH and LH

Question 39

What does FSH stimulate in males?

Answer 39

Stimulates Sertoli cell division, then secretion of inhibin (negative feedback), secretion of ABP – androgen binding protein.

Question 40

What does LH activate in males?

Answer 40

Acts on the Leydig cells to produce testosterone Most active form = dihydrotestosterone made by 5-alpha reductase Essential for sperm production

Question 41

How is testosterone maintained in high concentrations?

Answer 41

Binding of testosterone by androgen binding protein present in the seminiferous tubules.

Question 42

How long do sperm take to pass through the epididymis?

Answer 42

4-6 weeks

Question 43

Is the epididymis a single tube?

Answer 43

Yes

Question 44

Within the epididymis what is added to the sperm head and why?

Answer 44

Adds a glycoprotein coat over sperm head - prevents premature activation of acrosome

Question 45

Does the vas deferens passively carry spermatozoa?

Answer 45

No, contractions propel it along

Question 46

What three sex accessory glands produce seminal fluid?

Answer 46

Prostate, seminal vesicles and bulbourethal gland

Question 47

How many sperm per ml of semen?

Answer 47

20 million

Question 48

How much of seminal volume does each sex accessory gland make up?

Answer 48

2/3 -seminal vesicles 1/3 - prostate a few drops - bulbourethral

Question 49

What do sperm require for motility?

Answer 49

Fructose

Question 50

When do spermatozoa begin to swim?

Answer 50

After leaving the epididymis

Question 51

Lipid mediator hormone present in seminal fluid

Answer 51

Prostaglandin

Question 52

A pituitary hormone that can cause infertility when levels are raised ?

Answer 52

Prolactin

Question 53

What is one unique property of mature spermatozoa

Answer 53

They contain a modified lysosomal structure called the acrosome

Question 54

What is the acrosome derived from?

Answer 54

Golgi

Question 55

What is the acrosome

Answer 55

The acrosome is a large lysosome-like vesicle overlying the sperm nucleus. Contains acrosomal enzymes and common enzymes associated with lysosomes in somatic cells.

Question 56

Do spermatocytes arrest during either meiotic division?

Answer 56

No

Question 57

What supplies the fructose?

Answer 57

Seminal vesicles/ Vas deferens

Question 58

What cells line the epididymis?

Answer 58

Epididymis is covered by a two layered pseudostratified epithelium.

Question 59

What receptors do epithelial cells of the epididymis have?

Answer 59

Testosterone receptors

Question 60

In the basal compartment of the seminiferous tubules what do the cells undergo?

Answer 60

Repeated mitotic divisions