Reproduction - male anatomy/spermatogenesis

Question 1

What are testes?

Answer 1

Secrete male sex hormones and produce male gametes and sperm

Pass through inguinal ring

Question 2

What muscles are important for testes thermoregulation?

Answer 2

Dartos and cremaster muscles

Question 3

what are the structures within the testes and joining to body?

Answer 3

Seminiferous tubules
Rete testes
Efferent ductules
Epididymus ( head/caput, body/corpus, tail/cauda)
Spermatic cord (vas deferens, pampiniform plexus, cremaster muscle)

Question 4

What are within/between seminiferous tubules?

Answer 4

In the tubules: sertoli cells
Between tubules: Leydig cells

Question 5

What do sertoli cells do?

Answer 5

Control spermatogenesis by transferring developmental proteins to spermatocytes, they also remove material from elongating spermatids

Joined by gap junctions

Question 6

What do leydig cells do?

Answer 6

These produce testosterone and stimulate sertoli cells

Question 7

What is the pathway for testosterone production?

Answer 7

Leydig cell

Cholesterol>Pregnenolone>Testosterone

Sertoli cell
Testosterone?Dihydrotestosterone

Question 8

What controls testosterone production?

Answer 8

GnRH (hypothalamus)

LH/FSH (anterior pituitary)

LH > leydig cells
FSH > sertoli cells > receptors to be responsive to testosterone

Question 9

What happens if the pituitary gland is removed?

Answer 9

Testes shrink and no spermatogenesis

Leydig cells deteriorate and little/no testosterone output.

Question 10

What happens if the testes are removed?

Answer 10

Complete stop of testosterone production and helps control behaviour

Question 11

What is spermatogenesis?

Answer 11

The production of sperm

Question 12

How does spermatogenesis occur?

Answer 12

1. Spermatogonal stem cells develop and proliferate via mitosis (diploid)
2. Spermatocytes undergo meiotic division and become genetically different spermatids
3. Spermatids are packaged up and elongated to become spermatozoa via cytodifferentation

Question 13

Where is spermatozoa concentrated and matured?

Answer 13

In the retis testis and mature in the epididymus

Question 14

What happens in the caput/head of the epididymus?

Answer 14

The fluid from the sertoli cells is resporbed and the sperm is concentrated
The muscles propel the sperm forward as is not motile or fertile

Question 15

What happens in the corpus/body of the epididymus ?

Answer 15

The sperm matures and the environment is modified:
- loss of cytoplasmic droplet and nuclear chromatin condenses via disulphide bridges
-surface glycoproteins are added and the lipid composition of the membrane changes to fatty acids
-Metabolic activity is depressed to become dependent on fructose and prolong cell life
-cAMP content of tail increases to aquire motility

Question 16

What happens in the cauda/tail?

Answer 16

Sperm is stored

Question 17

What is the pampiniform plexus?

Answer 17

The veins around the testis to ensure cooling before circulating through the scrotum

Question 18

What are the accessory glands?

Answer 18

Ampulla
Bulbourethral gland
Prostate

Question 19

What is the composition of seminal plasma?

Answer 19

-Glycoprotein decapacitation factors
-Fructose and sorbitol
-Citric acid (stops coagulation)
-Buffers and ascorbic acid (vaginal pH)
-Acid phosphatase
-Prostaglandins to stimulation muscle contraction

Question 20

How does an erection/ejaculation occur?

Answer 20

1. Pelvic nerve is stimulated, leading to arterial dilation and an increase in blood flow
2. Relaxation of retractor penis muscle leads to straightening of sigmoid flexure
3. Muscles of vas deferens, seminal vesicles and prostate contract
4. Spermatozoa and seminal plasma are expelled

Question 21

What is the anatomy of a sperm?

Answer 21

Head - acrosome, nucleus
Mid - centriole and mitochondria
Tail - tail

Question 22

What is a sigmoid flexure?

Answer 22

A flexure so the penis can be kept in the body held by retractor muscles. Fibroelastic penis’s use this.

Question 23

What animals have as sigmoid flexure?

Answer 23

Bull, ram and boar

Question 24

What is the corpus cavernosum?

Answer 24

One of two columns of spongy tissue that runs through the shaft (body) of the penis. The corpus cavernosum forms most of the penis and contains blood vessels that fill with blood to help make an erection.

Question 25

What is the corpus spongiosum?

Answer 25

Another column of spongy tissue that surrounds the urethra

Question 26

What is a musculovascular penis?

Answer 26

Requires blood flow into the corpus cavernosum to become erect

Question 27

What species have a musculovascular penis?

Answer 27

Humans, stallions

Question 28

How do dogs mate?

Answer 28

1. Male mounts females, and 1st/2nd fractions of semen are ejaculated (1-2mins)
2. Male turns, and a 3rd fraction of semen is ejaculated (5-45mins) with inter-uterine deposition, while maintaining high pressure
3. The aminals are locked by the bulbus glandis

Question 29

What is the anatomy of a bull/ram?

Answer 29

Testes lie vertically in a pendulous manner
Sigmoid flexure/fibroelastic penis
Ram has filiform appendage to spray sperm

Question 30

What is the anatomy of a boar?

Answer 30

Testes are non-pendulous and are inverted, lying oblique.
Sigmoid flexure/fibroelastic penis
Corkscrew penis

Question 31

What is the anatomy of a stallion?

Answer 31

Testes lie horizontally, in pendulous manner
Musculovascular penis

Question 32

What is the anatomy of a tom cat?

Answer 32

Penis points backwards and the testes are located dorsally
Androgen dependent spines on the penis

Question 33

What is the tunica vaginalis?

Answer 33

A sheet of connective tissue forming the pouch the testis sit in

Question 34

What is the pampiniform plexus?

Answer 34

The network of capillaries for temperature control of the testes along with the cremaster muscles.