Male Reproductive Behaviour

Question 1

Purpose of behaviour

Answer 1

To promote opportunities for copulation and consequently increase probability of producing offspring

-obligatory component, priority

Question 2

Phases of Reproductive behaviour

Answer 2

Precopulatory: search for sexual partner - courtship - sexual arousal - erection - penile protrusion (from prepuce)

Copulatory: mounting - intromission - ejaculation

Postcopulatory: dismount - refractory period - memory

Question 3

Olfactory Communication

Answer 3

Via release of pheromones and other scents to signal reproductive status

-Flehmen behaviour: sensory neurons in nasal cavity detect scents that signal reproductive status

Question 4

Auditory Communication

Answer 4

Via calls, grunts, or song; acts as a long-range signal

-females tend to make more noise during estrus

Question 5

Visual Communication

Answer 5

Via postural changes (lordosis), displays aggression, and signs of heat. Needed for close encounters

Question 6

Tactile Communication

Answer 6

Via placing weight on females back in order to induce lordosis
- generally the final stimulus before copulation

Question 7

When is reproductive behaviour programmed?

Answer 7

During prenatal development when the hypothalamus either develops a surge center (females) or does not (males)

Question 8

Postnatal Exposure to Steroids

Answer 8

Required to express reproductive behaviour
- exposure to E2 and P4 in ovariectomized females results in female reproductive behaviours
- exposure to T or E2 in orchiectomized males will induce male reproductive behaviours

Question 9

Which male takes longer to stop exhibiting repro behaviour… before puberty or after?

Answer 9

Males castrated after puberty take longer to stop exhibiting repro behaviour than those castrated before puberty since those signaling pathways are already established

Question 10

Brain regions associated with repro behaviour?

Answer 10

Nucleus accumbens, medial preoptic area, hypothalamus, and amygdala

Question 11

What is dopamine associated with?

Answer 11

Pleasurable reward and motivation and facilitates male reproductive behaviour

Question 12

What happens after sensory stimulation and stimulation of hypothalamus?

Answer 12

Posterior pituitary releases oxytocin which induces smooth muscle contractions which move spermatozoa from epididymis to urethra

Question 13

What does an erection in the penis require?

Answer 13

• Elevated arterial blood flow - increases intrapenile pressure
• Dilation of corporal sinusoids - helps receive and trap blood to prevent outflow in order to maintain erection until ejaculation
• Restricted venous outflow
• Relaxation of retractor penis m for penis protrusion and subsequent straightening of sigmoid flexure (in fibroelastic penis

Question 14

Steps of Erection in the Nervous System

Answer 14

1. Erotogenic stimuli cause sensory nerves to fire
2. Sensory nerves stimulate supraoptic and paraventricular nuclei within hypothalamus
3. Stimulation of parasympathetic nerves that innervate penile arterioles
4. Parasympathetic nerve terminals release nitric oxide (NO)
5. NO inititates biochemical cascade that causes erection

Question 15

How many pelvic thrusts do bulls require before semen deposition?

Answer 15

Only 1

Question 16

What copulatory behaviour is unique in dogs?

Answer 16

Lock/tie

Question 17

What is the first stage of Copulatory lock/tie in dogs?

Answer 17

Male mounts, intromission, pelvic thrusting, then deposition of first and second fractions of semen

Question 18

What is the second stage of Copulatory lock/tie in dogs?

Answer 18

Penis is held by vaginal muscles for 5 - 45 mins while third fraction of semen pushes second fraction into uterus

Question 19

Ejaculation

Answer 19

Simple neural reflex for expulsion of spermatozoa caused by stimulation of the glans penis and coordinated contraction of urethralis, Bulbospongiosus, and ischiocavernosus muscles

Question 20

Sequence of ejaculation fluid fractions in Rams/Bulls

Answer 20

1 fraction

Question 21

Sequence of ejaculation fluid fractions in Stallions

Answer 21

Sperm rich 1st fraction (3-4 jets) and a 2nd gel fraction (3-4 jets)

Question 22

Sequence of ejaculation fluid fractions in Boars

Answer 22

First accessory fluid, gelatinous pellets and few sperm, second sperm rich, and third gel fraction (helps plug cervix and prevent fertilization by other males)

Question 23

Sequence of ejaculation fluid fractions in Dogs

Answer 23

First pre-sperm prostate-derived fluid, second sperm rich, and third prostate fluid

Question 24

Postcopulatory Behaviour

Answer 24

Dismount, refractory period, and memory

Question 25

Refractory Period

Answer 25

Part of satiation rather than exhaustion

• Satiation: further stimuli will not cause immediate responsiveness or motivation
• Exhaustion: no further sexual behaviour can be induced

Question 26

What does refractory period depend on?

Answer 26

Depends on degree of rest before copulation, age and species of male, degree of female novelty, and number of previous ejaculations