Rutgers - Biology 2 - Reproduction 1

Mitosis (No Gametes)

Meiosis (Gametes)

Single parent → clone

Egg + sperm (2 parents) - Sperm: small, motile, and flagellated - Egg: large, non-motile, and lots of nutrients

Good environment → successful offspring

Any environment

-Parthenogenesis (diploid eggs) - Budding, fission, fragmentation (offspring via mitosis)

Fertilization

- Fast
- No mate needed
- 100% of genes are passed on to next generation

Variation (genetic recombination)

Bacteria and Hydra

Mammels

Male gonads
- Seminiferous tubules with sertoli cells
- Leydig cells (between seminiferous tubules)

- Produce sperm and secrete inhibin and ABP
- Secrete testosterone

Sperm transport (3 weeks), maturation, and storage

Coiled duct in testes

Surrounds testes and epididymis (suspended from groin)

- Cooling 1-2 degrees C
- Increase sperm longevity

- Urethra
- Erectile tissue (3 parallel columns) - Glans (tip of the penis)
- Prepuce (foreskin)

- Delivers sperm to female reproductive tract

Seminal Vesicles - Secretes pigment into vas deferens - Fructose (energy)
- Prostaglandins (lipids): stimulate uterine contractions Prostate Gland
- Secretes anticoagulant enzyme and citrate (nutrient) into urethra Bulbourethral Gland
- Mucus: neutralizes acid in urethra (some sperm also gets caught → pre-cum)

- Seminal Vesicles - Prostate Gland
- Bulbourethral Gland (2 → each side of urethra)

Tube from epididymis to pelvic cavity

Tube used for sperm to leave epididymis

Runs through middle of penis

Carries urine and semen (at different times)

Testes (seminiferous tubules) → epididymis → vas deferens → ejaculatory duct → urethra → Penis → release from body

- Testes that contain the seminiferous tubules
- Sperm travels through/stored in epididymis
- Sperm moves from epididymis to vas deferens: sperm ducts
- 1 from each epididymis
- Extend from scrotum to pelvic cavity
- Ejaculatory duct: passes through prostate gland, joins urethra
- Urethra: carries urine and semen through penis

Spermatogonium → Mitosis → 2n → Meiosis 1 → 1n secondary spermatocyte → Meiosis 2 → Spermatid → Differentiation → Sperm

- In the embryonic testes: Primordial germ cells (2n)
- Divide & differentiate → Spermatogonial stem cells (2n)
- WAIT FOR PUBERTY
- At puberty: In the seminiferous tubules Spermatogonial stem cells
- Mitosis → spermatogonia (2n)
- Spermatogonia mitosis → Primary (1º) spermatocyte (2n) And A spermatogonia cell (2n)
- At puberty: 1º spermatocyte (2n) → Meiosis
- Meiosis I → 2º spermatocytes (n)
- Meiosis II → 4 spermatids (n)
- At puberty Spermatids (n) Differentiate at sperm

→ AP releases 2 gonadotropins (tropic hormones that target gonads)
- luteinizing hormone (LH) , follicle stimulating hormone (FSH)

Targets Leydig cells (testes, gonads for males)
■ → Leydig cells produce, secrete testosterone, other androgens ● Rising levels of Testosterone inhibits Ant. pit. (LH) and Hypothalamus (GnRH) production
■ → stimulates spermatogenesis

■ Testosterone Stimulates Puberty in males (long term effect)
○ Period of sexual maturation ■ Adolescent growth spurt
■ Growth of 1° male caracteristics
- growth of sex organs (penis and testes)
■ Growth of 2 ° male sex characteristics
○ (2° sex characteristics
- physical, behavioral differnces betwen males & females, not directly related to reproduction)
○ For males: Facialody hair, deep voice, muscle development

○ Stimulates development of seminiferous tubules
○ Stimulates Sertoli cells (found in seminiferous tubules in testes) to produce, secrete androgen binding protein (ABP)
■ Binds testosterone
■ Helps maintain high testosterone levels (spermatogenesis occur correctly) ■ Allows testosterone to be sequestered
■ Not a hormone
○ FSH secretion inhibited by inhibin
- peptide hormone secreted by Sertoli cells