- Healthy spermatozoa should be deposited high in the vagina at or near the cervix (male factor).
- The spermatoza should undergo changes (capacitation, acrosome reaction) and acquires motility (cervical factor).
- The motile spermatozoa should ascend through the cervix into the uterine cavity and the fallopian tubes.
- There should be ovulation (ovarian factor).
- The fallopian tubes should be patent and the oocyte should be picked up by the fimbriated end of the tube (tubal factor).
- The spermatoza should fertilize the oocyte at the ampulla of the tube.
- The embryo should reach the uterine cavity after 3-4 days of fertilization.
- The endometrium should be receptive (by oestrogen, progesterone, IGF-1, cytokines, integrins) for implantation and the corpus luteum should function adequately.
On the basis of type of nucleic acid : Classification Example DNA viruses Poxvirus Herpes virus Adenovirus Papova virus Parvo virus RNA viruses Myxo virus Rhabdo virus Corona virus Picorna virus Toga virus Arena virus Reo virus Retro virus On the basis of strandedness : Classification Example Double stranded Hepatits B virus Herpes simplex virus Small pox virus Rota virus Adenovirus (all DNA viruses except parvo virus) Single sranded Hepatits A virus Polio virus Dengue virus( Aedes aegypti ) Influenza virus Measles virus (all RNA virus except reo virus) On the basis of presence of envelop : Classification Example Wnveloped virus Hepatitis B virus Herpes simplex virus Small pox virus Non-enveloped virus Hepatits A virus Rota virus Polio virus ...
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