1. Male Reproductive Biology
The Testes
Gamete Development (sperm)
Hormonal Production (testosterone)

2. The Sperm’s Journey
Spermatids released into lumen of seminiferous tubules
Move through tubules
Stored in Epididymis
Sperm is produced in the testes and stored in the attached epididymis. During ejaculation, sperm are propelled up the vas deferens, two ducts that pass over and behind the bladder. Fluids are added by the seminal vesicles and the vas deferens turns into the ejaculatory ducts which join the urethra inside the prostate gland. The prostate as well as the bulbourethral glands add further secretions, and the semen is expelled through the penis.

3. The SPERM genetic material Enzymes dissolve egg membrane Head
Middle piece
Head
Tail
Enzymes dissolve egg membrane
Each sperm cell has three parts: a head, middle piece, and tail. An acrosome at the head tip produces enzymes that help penetrate the female ovum (egg). During conception, chromosomes (genetic material) in the nucleus (cell control center) join with chromosomes in the ovum. The middle piece contains mitochondria, structures that provide energy for the sperm. The mitochondria are tightly spiraled around the axial filaments (contractile portion) of the flagellum (tail). Centrioles form the tail, which moves the sperm toward the ovum. An ejaculation (ejection of sperm from the penis) has 300 to 500 million sperm.
genetic material
microtubules (cilia and flagella)

4. Seminal vesicles & Prostate gland: Provide seminal fluid
The seminal vesicles are a pair of glandular sacs that secrete about 60% of the fluid that makes up the semen in which sperm are transported. Seminal fluid provides nourishment for sperm.
The prostate gland is a walnut-sized glandular structure that secretes about 30% of the fluid that makes up semen. The alkaline quality of the fluid neutralizes the acidic environment of the male and female reproductive tracts. A muscle at the bottom of the prostate gland keeps the sperm out of the urethra until ejaculation begins. The prostate gland is very sensitive to stimulation and can be a source of sexual pleasure for some men.
Cowper’s glands are two pea-sized glands at the base of the penis under the prostate that secrete a clear alkaline fluid into the urethra during sexual arousal and before orgasm and ejaculation. These glands produce mucoid, pre-ejaculatory fluid in the urethra that acts as a lubricant for the sperm and coats the urethra as semen flows out of the penis.
Seminal vesicles & Prostate gland: Provide seminal fluid
Cowper’s gland: Provide pre-ejaculatory fluid (lubricant)

5. The human penis is made up of three columns of erectile tissue:
the two corpora cavernosa dorsally (singular: corpus cavernosum) and one corpus spongiosum ventral. The end of the corpus spongiosum is enlarged and bulbous-shaped and forms the glans penis. The glans supports the foreskin or prepuce, a loose fold of skin that in adults can retract to expose the glans. The area on the underside of the penis, where the foreskin is attached, is called the frenum (or frenulum).
The urethra, which is the last part of the urinary tract, traverses the corpus spongiosum and its opening, known as the meatus, lies on the tip of the glans penis. It is both a passage for urine and for the ejaculation of semen.

6. Erection Facilitates penetration Occurs when sexually aroused (mostly)
Mechanism: artery dilation  filling of corpora
An erection is the stiffening and rising of the penis, which occurs in the sexually aroused male, though it can also happen in non-sexual situations. The primary physiological mechanism that brings about erection is the autonomic dilation of arteries supplying blood to the penis, which allows more blood to fill the three spongy erectile tissue chambers in the penis, causing it to lengthen and stiffen. The now-engorged erectile tissue presses against and constricts the veins that carry blood away from the penis. More blood enters than leaves the penis until an equilibrium is reached where an equal volume of blood flows into the dilated arteries and out of the constricted veins; a constant erectile size is achieved at this equilibrium.
Erection facilitates sexual intercourse though it is not essential for various other sexual activities. Although many erect penises point upwards (see illustration), it is common and normal for the erect penis to point nearly vertically upwards or nearly vertically downwards or even horizontally straightforward, all depending on the tension of the suspensory ligament that holds it in position. Stiffness or erectile angle can vary
Viagra: Part of the physiological process of erection involves the parasympathetic nervous system causing the release of nitric oxide (NO) in the corpus cavernosum of the penis. NO binds to the receptors of the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation (vasodilation) in the corpus cavernosum, resulting in increased inflow of blood and an erection.
Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum. The molecular structure of sildenafil is similar to that of cGMP and acts as a competitive binding agent of PDE5 in the corpus cavernosum, resulting in more cGMP and better erections. Without sexual stimulation, and therefore lack of activation of the NO/cGMP system, sildenafil should not cause an erection. Other drugs that operate by the same mechanism include tadalafil (Cialis®) and vardenafil (Levitra®).
Sildenafil is metabolised by hepatic enzymes and excreted by both the liver and kidneys. If taken with a high-fat meal, there may be a delay in absorption of sildenafil and the peak effect might be reduced slightly as the plasma concentration will be lowered.
VIAGRA:
Not an aphrodisiac
Sildenafil increases levels of cGMP which causes vasodilation of the corpora
Without sexual arousal, it can not cause an erection

7. Male Hormonal Functioning

8. Male hormonal function
HYPOTHALAMUS
GnRH
PITUITARY
FSH -> + spermatogenesis
LH -> + testosterone
testosterone -> - GnRH. LH
FSH
TESTES
TESTOSTERONE

9. Testosterone Sperm maturation development of penis and testes
Male secondary sexual characteristics
Axillary hair,
larynx,
oil and sweat gland secretion
Threshold for sexual activity and libido
muscle anabolism
Risk of prostate cancer
Androgen: A male sex steroid hormone. Testosterone is the principal mammalian androgen.
Testosterone: The principal androgen found in males

11. Testosterone and Aggression
Differences in testosterone don’t tell us about individual differences in levels of aggression
Individuals with more T not more aggressive

12. Effect of Social cues on hormonal and sexual behavior
Russ fernald
Astatotilapia burtoni African cichlid fish
The social system of a. burtoni centers on adult males of two types: those with and those without territories. Territorial (T) males are brightly colored, with blue or yellow basic body coloration, a dark black stripe through the eye (lachrymal), vertical black bars on the body from the opercula to the tail, a black spot on the tip of the gill cover and a large red humeral patch just behind it. In contrast, nonterritorial (NT) males are cryptically colored, making them difficult to distinguish from the background and from females that are similarly camouflaged
The brain-pituitary-gonadal axis that controls vertebrate reproduction has been conserved throughout the evolution of vertebrates as evidenced by the fact that the primary signaling molecule, gonadotropin-releasing hormone (GnRH), has had the same size and structure for 500 million years of vertebrate evolution. Understanding how behavior influences this essential physiological axis should reveal fundamental principles about the mechanisms of reproductive control.
a change in the social status of an individual male causes a reversible change in the size of an identified group of GnRH containing neurons in the preoptic area of the brain. In females, similar changes in cell size occur, but they are controlled by the reproductive state, not the social scene. when adult teleost males become socially dominant by acquiring a territory, neurons that contain gonadotropin releasing hormone (GnRH) enlarge significantly. Conversely, losing a territorial fight results in those same cells decreasing in size.
A. burtoni is a type of African cichlid fish. It lives in a hierarchical social system where showy dominant males defend small territories that are used for courtship and breeding.
dominance among male cichlids is reversible: If a subordinate successfully challenges a dominant male in a face-to-face confrontation, the dominant fish will lose his status and with it his vibrant coloring, black eyebar and the ability to produce sperm.
this change in social status also causes a change in a group of brain cells that produce gonadotropin-releasing hormones—chemical signals from the brain to the gonads that regulate sexual development in all vertebrates, including people. As the male fish ascends toward dominance, these brain cells grow eight times bigger in volume and begin producing large amounts of the hormone. As a result, the fish becomes more aggressive, his appearance changes dramatically and his gonads mature. When the male descends in status, the opposite occurs—the hormone-producing brain cells decrease in size, the ostentatious colors and stripes disappear, and the testes shrink and the male becomes infertile.
subordinate males can become dominant within minutes of an opportunity to do so, displaying dramatic changes in body coloration and behavior,"
low-ranking male cichlids can quickly become leading men without even putting up a fight. In fact, a drab subordinate male cichlid will begin physically transforming into a colorful dominant male as soon as he notices that his competition is no longer around when the dominating male is removed, the subordinate male perceives an opportunity to advance in social status and responds both behaviorally and by turning on genes that ultimately make him capable of reproducing," that is, changes in social status trigger cellular and molecular changes in the brain, which could have significant implications for understanding how other vertebrates, including humans, respond to social information (note similarity to case of genetic expression after mothers lick the baby rats)
The sexually dominant male (bottom) has vivid coloration and special markings.

13. Female reproductive biology Menstrual Cycle
HYPOTHALAMUS
Follicular phase
(first half of cycle)
GnRH
ANTERIOR PITUITARY
FSH LH
OVARY
Follicle-stimulating hormone (FSH): The hormone of the anterior pituitary gland that causes development of an ovarian follicle and the maturation of its oocyte into an ovum.
Luteinizing hormone (LH): A hormone of the anterior pituitary gland that causes ovulation and development of the ovarian follicle into a corpus luteum.
Estradiol: The principal estrogen of many mammals, including humans.
Estrogen: A class of sex hormones that cause maturation of the female genitalia, growth of breast tissue, and development of other physical features characteristic of females.
Follicle
Estrogens

14. Estrogen effects increases progesterone receptor density in breasts
Initiates proliferative phase in uterus
Causes changes in cervical mucous
tangled fibers to line up, allowing sperm to get through
cervix closes soon after ovulation

15. Copyright © Allyn & Bacon 2004

17. HYPOTHALAMUS
GnRH
ANTERIOR PITUITARY
FSH LH
OVARY
Follicle
Corpus Luteum
Estrogens
Progesterone
UTERUS
Endometrium, Cervix, Vagina

18. Progesterone Effects
P is secreted by the Corpus Luteum after ovulation
Increased concentration in breast in luteal phase
increases tenderness
increases nipple sensitivity
Initiates secretory phase of endometrium
Heavy vascularization
Secretion of nutrient rich medium for embryonic growth
Signals the pituitary to stop producing LH

19. Secretory Phase of Uterus

20. No fertilization Fertilization
Corpus Luteum regresses after about 12 days
Progesterone products drops off sharply
Endometrium sloughs off (menstruation)
Fertilization
Corpus luteum remains active
Progesterone levels remain high  uterine lining remains strong
Implantation occurs
hCG from fetus takes over

21. In rabbits, the act of coitus stimulates the pituitary gland to release gonadotropin which induces ovulation & increases the probability of pregnancy.

22. Oxytocin: A hormone secreted by the posterior pituitary gland; causes contraction of the smooth muscle of the milk ducts, the uterus, and the male ejaculatory system.
Prolactin:A hormone of the anterior pituitary gland, necessary for production of milk; has an inhibitory effect on male sexual behavior.

23. Organizational effect:
The effect of a hormone on tissue differentiation and development.
Activational effect:
The effect of a hormone that occurs in the fully developed organism; may depend on the organism’s prior exposure to the organizational effects of hormones.
Lordosis: A spinal reflex seen in many four-legged. Female mammals; arching of the back in response to approach of a male or to touch the flanks, which elevates the hindquarters.

24. defeminization
masculinization

25. Pheromone:
A chemical released by one animal that affects the behavior or physiology of another animal; usually smelled or tasted.
Vomeronasal organ (VNO):
, mediates the effects of some pheromones
Lesion to VNO:
female rat fails to recognize male as such
Behaves as male
This suggests bipotentiality of adult female brain (male/female)
Copyright © Allyn & Bacon 2004

26. Effects of Pheromones
female animals housed together -> stop estrous cycle
synchronization of estrous cycle by pheromone in a male’s urine.
female animals housed with males -> early onset of puberty
Termination of pregnancy when new male other than the one that impregnated the female.