Fertilization
The union of the egg and the sperm is called fertilization. It results in
the production of a single diploid cell called zygote.
At the time of ovulation, the ovum is fully matured and it enters the
infundibulum of the uterine tube and passes into the ampulla. Fertilization of
the ovum occurs in the ampulla of the uterine tube. One spermatozoan pierces
the egg membrane, zona pellucida and enters the ovum. Polygamy (entry of
more sperms) is avoided by the formation of fertilization membrane around
the ovum.
In vitro fertilization (Test tube babies)
The so called test tube babies are produced by the technique of in
vitro fertilization. (In vitro = outside the body, as against in vivo = within the body). This technique is being increasingly used in couples who are not
able to achieve fertilization in the normal way
Gonadotropins are administered to the woman to stimulate growth
of follicles in the ovary. Just before ovulation, the ovum is removed (using an
aspirator) and is placed in a suitable medium. Spermatozoa are added to the
medium. Fertilization and early development of the embryo takes place in
this medium.
The process is carefully monitored. When the embryo is at the
8-celled stage, it is put inside the uterine endometrium. Successful
implantation takes place in about 20 percent of such trials. The techniques
are complex and need a team of well trained experienced personnel with
high degree of skill.
The success rate is only about 20% and 2 or 3 attempts may be necessary. It is also very expensive. The first success with this technique was achieved by Steptoe and Edwards of UK in 1978. However successful ‘test tube babies’ have been produced in many countries including India.
Gamete Intra fallopian transfer (GIFT)
It is a newer method in which the fertilized ova are introduced into
the fallopian tube from where they naturally pass to the uterus for
implantation. This method is considered to have a higher success rate than
IVF. An even newer technique is the introduction of a single sperm into the
ovum by microinjection.
Related Topics in Zoology:
Bio Zoology All Important Topics
- Human Physiology Introduction
- Nutrition
- Carbohydrates Poly hydroxyaldehydes (or) ketones
- Proteins (Polypeptides)
- Lipids
- Vitamins – Functions Of Vitamins
- Deficiency of Vitamin
- Minerals – Water – Role of water
- Balanced diet
- Obesity
- Digestive System
- Dental Caries (Tooth decay)
- Root Canal Treatment
- Peptic ulcer
- Hernia and Types
- Appendicitis (Appendix)
- Gall Stones
- Hepatitis
- Fractures – Types of fractures
- Mechanism of fracture
- Dislocation of joints
- Arthiritis
- Rickets and Osteomalacia – Orthopedics
- Muscles
- Mechanism of muscle contraction
- Types of muscle contraction
- Myasthenia Gravis
- Respiration – Process of pulmonary respiration
- Mechanism of Breathing
- Regulation of Respiration
- Pneumonia Tuberculosis Symptoms Treatment
- Bronchitis – Acute bronchitis, Chronic Bronchitis Causes
- Circulatory System – Functioning of Human heart
- Cardiac Cycle
- Coronary blood vessel and its significance
- Myocardial infarction
- Angina pectoris
- Angiogram – Angioplasty
- Atherosclerosis
- Heart block Echo cardiography Heart Valves
- Rheumatic Heart Disease (RHD), ICCU – (Intensive Coronary Care Unit)
- Blood Pressure
- Heart transplantation
- Pulse rate
- Cardio Pulmonary Resuscitation (CPR)
- Blood – Composition of plasma – Blood cells
- Clotting of Blood or Haemostasis
- Thrombosis
- Nervous system Co-ordination systems
- The Brain – Fore Brain, Midbrain, Hindbrain
- Memory
- Sleep – Types of sleep
- Stroke – Brain haemorrhage
- Alzheimer – Meningitis (Brain fever)
- Conditioned reflex
- Electroencephalography EEG
- Right and Left brain concept
- Spinal cord functioning
- Chemical co-ordination – Functions of Endocrine glands
- Hypothalamus
- Pituitary gland – hormone
- Hormones of Neurohypophysis – vasopressin
- Thyroid gland
- Parathyroid Gland
- Pancreas
- Adrenal gland
- Gonads
- Receptor Organs – Eye
- Photochemistry of Retinal visual Pigments
- Errors of refraction
- Optometry – Retinopathy
- Cataract – Lens Replacement – Glaucoma – Nyctalopia
- Eye Infections and Eye Care
- Ear
- Mechanism of hearing
- Defects of the ear
- Hearing Aid – Noise pollution
- Skin and functions of skin
- Melanin functions
- Effects of solar radiation / UV radiation – Skin grafting
- Dermatitis
- Tongue – Mechanism of Stimulation
- Excretion Ureotelism Nephron
- Mechanism of urine formation
- Renal Failure, Dialysis, Kidney Machines
- Kidney stone – Kidney transplantation
- Diabetes mellitus
- Functioning of male reproductive system
- Functioning of female reproductive system
- Ovulation and fate of the ovum – Menstrual cycle
- Fertilization
- Birth control