Sexual Reproduction in Humans

Male Reproductive System consists of:

 

1.Testes:
  - produce sperm + hormones
  - under the influence of pituitary gonadotrophins, FSH +LH
  - contains scrotum 
  - kept 2 °C <normal body temperature
  - optimal for sperm production (spermatogenesis).

2. Ducts:

  - vasa efferentia + vas deferens

  - transport sperm to urethra

 

3. Glands:

  - prostate gland, Cowper’s gland, seminal vesicles

  - contribute fluid to semen.

4. Sperm (in seminal fluid)

  - discharged from body thru penis ( intromittent organ).

5. Each testis:

  - consists of about a thousand seminiferous tubules.

6. Each tubule:

  - lined by germinal epithelium

  - which divides to give rise to sperm

  - + two months.

 

 

1. Interstitial cells:

   - between seminiferous tubules

   - contain Leydig cells 

   - produce testosterone

   - influence of LH (in pituitary gland).

 

2. Testosterone:

   - stimulates development + maintenance of male secondary sexual
     characteristics + accessory sex organs.

 

3. Spermatogenesis:

    - starts at puberty

    - when FSH stimulates series of cell divisions

    - of germinal epithelium

    - of seminiferous tubules.

 

4. Spermatozoan cell:

    - cytoplasm disappeared during development.

 

 

 

 

 

 

 

 

 

 

 

 

5. Acrosome:

    - large lysosome

    - enzymes to digest outer membranes of the egg (female gamete)

 

6. Mitochondria - provide energy for locomotional flagella movement.

Human female reproductive system consists of:

1. Pair of ovaries:
   - which produce ova
   - carried by Fallopian tubes (oviductus)
   - to uterus.

2. cervix - muscular ring at outer end of uterus.

3. vagina – opening to outside of body.

 

1. At birth:

   - ovaries contain about two million follicles

   - which started to divide by meiosis,

   - but stopped at prophase I (primary oocytes).

   - subsequent development at monthly intervals (menstrual cycle).

 

2. Oogenesis is regulated by the pituitary hormones FSH + LH. 

 

3. Ovulation + development of secondary sexual characteristics

   + uterine changes in preparation for implantation of a fertilised egg

   - controlled by the ovarian hormones (oestrogen + progesterone).

 

4. Fertilisation:

   - occurs in the Fallopian tubes

   - and the zygote is transported to the uterus

   - by the action of cilia lining.

 

5. Development of the zygote + embryo is viviparous