basics of embryology

2. EMBRYOLOGY
 Study of developmental process
amazing integration of increasingly complex
phenomenon
 EMBRYOGENESIS (Organogenesis)
 period of first eight (08) weeks from a single
cell to establishing organ primodia.
 FOETAL PERIOD
 from 9th
week to birth in which differentiation
continues while foetus grows and gains weight.

3. REPRODUCTION OF CELLS
 Meiosis and cyto differentiation
 Reduce number;diploid (46 ) to haploid (23)
 Alteration in shape of germ cells
 Fertilization of spermatozoa and oocyte
 Zygote formation

4. Somatic cell:
 23 pair or diploid chromosome
 22 pair of matching chromosome
“autosome”
 One pair of “sex chromosome”
 XX--genetically female
 XY-- genetically male
 Pairs not in proximity
 closer in meiotic division

5. CELL DIVISION
Interphase – Between
 G1;1 to several hrs
 Respond to growth factors
 S; 6-8 hrs
 DNA replication
 G2; 2-4 hrs
 Preparing for division

6. Mitosis: (1 – 2hrs)
 Prophase – Before
 Metaphase – After
 Anaphase – So much
 Telophase – End of relationship.

8. MEIOSIS (DECREASE IN NUMBER)
Meiosis-1 (HETEROTYPICAL)
 Prophase
 Leptotene Stage (RIBBON)
 Zygotene Stage (YOLKED TOGETHER)
 Pachytene Stage (THICKNESS)
 Diplotene Stage ( DOUBLE)
 Diakinesis Stage
 Metaphase 1
 Anaphase 1
 Telophase 1
Meiosis-2 (HOMOTYPICAL)

10. SIGNIFICANCE OF MEIOSIS
1. Haploid number of chromosomes
2. Half the amount of DNA
3. Genetic Variability
1. Cross overs
2. Random distribution

11.  Crossovers
 Chiasma formation

12. THANK YOU