1. بسم الله الرحمن الرحيم Parthenogenesis
التكاثر العذري

2. التكاثر العذري Parthenogenesis
Definition:تعريف التكاثر العذري
Is the ability of oocytes to be produced embryos and individuals without any fertilization, or without participation of sperm.
Parthenogenesis is divided into two types: -
أ- التكاثر العذري الطبيعيِ A-Natural Parthenogenesis
Parthenogenesis is happens in certain species of living organisms and reproduction by sexual and natural parthenogenesis, especially in some types of invertebrates such as some worms, molluscans, freshwater crustaceans (Daphnia) and insects such as bees, ants and wasps>

3. I- Natural Parthenogenesis in invertebrate
parthenogenesis occurs in: -
I- Natural Parthenogenesis in invertebrate
1- تكاثر عذري يحدث من وقت لآخر Sporadic
This type occurs with irregular shape in terms of timing, may depend on season and availability of environmental conditions, it was noted this type of parthenogenesis in virgin grade squamous wings as in the worm bed Ghazدودة الغز (Bambyx mori) and individuals resulting from this type are females.

4. 2- تكاثر عذري مستمر وثابت 2-Constant
This type happens regularly and is the type of individuals resulting from this type are males as in the bees النحلand the individual resulting has a single-group chromosome (ie, has half the number of chromosomes = 1n).
3- تكاثر عذري دوري Cyclic
This type occurs with a regular shape, after every normal sexual reproduction occurs parthenogenesis and the example of this is aphid from Aphidiae species حشرة المن ( من فصيلة أفيدي) .

5. II- Natural parthenogenesis in vertebrates
Occurs in some vertebrate species, as in some fish, amphibians and lizards, which overcome the process of doubling the genetic material or chromosomes in different ways, in lizards there are approximately 15-type, parthenogenesis occur in them as in the lizard reclamation or like orchid flagellar tail ( (سحلية سوطية الذيلof the genus Smida Force (Cnemidophorus uniparenes) which reproduction by parthenogenesis only and there have not males in these species, but females practiced the mating behavior among themselves without fertilization.

6. In mating season, females with low concentration of estrogen after ovulation play the role of the male and jump on the female that in the process of ovulation, and so the cycle continues between two females one play the role of the male (with low estrogen) and the other play the role of the female (with high estrogen)(Figure 58),and the eggs which reproduction by parthenogenesis in lizards produces only females. (Why parthenogenesis in lizards produce females?) There is also a strain of turkey reproduction by naturally parthenogenesis and the resulting embryos are males and the male can reproduction and produce both male and female. (Why parthenogenesis in birds they only produce males?)

7. (Why parthenogenesis in lizards produce females only?)

8. (Why parthenogenesis in birds they only produce males?)
صورة لذكر من الديك الرومي نتج من تكاثر عذري طبيعي عند تزاوجه ينتج نسبة متساوية من الذكور والإناث.

9. ب- التكاثر العذري الإصطناعيB_ ArtificialParthenogenesis
This type of parthenogenesis does not spread among the organisms in the normal case, but we can do parthenogenesis experimentally by stimulating the eggs to be divided and form embryos without the contribution of sperm to produce full configuration members.

10. * Methods of artificial parthenogenesis
Researchers in the field of experimental embryology such as (Whillim Ruox, Epele, Hertwing, and Loeb) try to produce embryos in organisms, that originally there is no parthenogenesis breeding, by means of mechanically as puncture of eggs of frogs by needle or by electrical stimulation of the eggs (stream of weak some what) or by placing eggs in a solution containing some chemical components that are active ion-exchange membrane on both sides of the egg (such as potassium, sodium, calcium chloride) or weak organic acids (such as lactic acid and fat solvents as ether, acetone, and alcohol).

11. In the types of organisms such as echinoderms (sea urchinقنفذ البحر ) eggs cannot to be an embryos without fertilization under natural conditions, but when these eggs exposed to special treatments, they begin the process of cleavage and form embryos which is known parthenogenesis. To make the parthenogenesis, put the eggs of sea urchin in a low-salt solution for a short period leads to occurs of a cleavage process in the egg and produce embryos.

12. The interpretation of artificial parthenogenesis:
تفسير حدوث التكاثر العذري الأصطناعي:
It is known that, most of the eggs in the female ovaries are in first meiosis division(Primary oocytes بويضة ابتدائية) and some of them complete the first meiosis before ovulation and others complete the first meiosis during ovulation to produce a Secondary oocytesالبويضة الثانوية and the first polar body.

13. Then, the oocytes complete the meiosis division in most organisms within the oviduct to produce a mature eggالبويضة الناضجة and second polar bodyوالجسم القطبي الثاني , either during the fertilize oocytes with sperm, which urges them to complete the meiosis division, as well as a result of contact of sperm with a membrane the oocyte they are form a fertilization membrane to prevent the entry of more than sperm to the oocyte and then urges them to enter at the stage of cleavage after the merger of male and female nucleus.

14. During the ion exchange across the membrane between the egg cytoplasm and ocean around, the egg come out the contents of the vesicles known as cortical granules reaction تفاعل احلويصلات القشرية) )to be form a clear layer or gels around them to prevent the fertilized by more than sperm.
But prior to the merger between the male and female pro-nucleus, the genetic material will be duplicated and all chromatides turned to chromosomes, then male and female nucleus merging to form nucleus of zygote, which is the first nucleus of the first cell of the embryo where cleavage phase begins in the normal matting.

15. Factors that control the parthenogensis process
To induce the parthenogenesis process, main three factors must be overcome, which occurs during normal sexual reproduction between sperm and egg are:-
1- The mechanical stimulation of the oocyte egg that result from contact of the sperm with the egg in the natural matting.
2 - Provide a second number of the chromosome set any binary number of chromosomes (2n)
3- The central body and strings of the spindle division and cleavage.
For inducing the artificial parthenogenesis, it can be explained by overcome the above factors process through experiments conducted on living organisms and that have not been the Artificial parthenogenesis.

16. I:The mechanical or chemical activation of oocytesأولا : التنبيه والتنشيط الميكانيكي أو الكيميائي للبويضات :
The treatment with chemicals or acupuncture with needle minutes or even electrical shock to the oocyte is a catalyst for the oocyte membrane to complete the meiosis II division.
The mating behavior that occurs among female lizards wip tail with parthenogenesis, this breeding behavior, urges on the process of ovulation is also a mechanical stimulus to activate the eggs.

17. It has been observed experimentally that the pricked of unfertilized amphibians eggs with a sterilized needle, activates and begins to cleavage. This mechanical stimulate works to flow of sodium ions into the oocyte and release of calcium ions to initiate the cortical granulosa reaction in the oocytes.

18. Also found that when put female sea urchin eggs containing a large germinal disc and the animal pole appearing a notch or a clear reduction (Figure 60). When treatment of these eggs and place it in the low concentration fluids for a short time, it can not be activated soon and it seems to rotate shape and the form of egg fertilization membrane is formed, as a result of the characteristic low osmosis between the solution concentration and the egg cytoplasm (high concentration somewhat). This is a stimuli to the process of ionic chemical exchange between the cytoplasm of the sea urchin egg and the solution.

19. شكل (60): التكاثر العذري الإصطناعي في بيض قنفذ البحر بواسطة التنبيبه الكيميائي عند تعريض بيض قنفذ البحر غير المخصب لمحلول ملحي منخفض لمدة قصيرة فإن البيض تختفي فيه الثلمة ويصبح كامل الإستداره مما يدل على انه كأنه بيض مخصب ثم يتفلج عذريا.

20. شكل (61): التكاثر العذري الإصطناعي في بيض قنفذ البحر بواسطة التنبه الكيميائي عند تعريض بيض قنفذ غير المخصب لمحلول ملحي منخفض لمدة طويلة فإن البيض يدخل مرحلة التفلج تصبح فيها عدة أنويه( ثلاث أو اثنتان) من الجسم القطبي الأول أو الثاني أو نواة واحد هي نواة البويضة الناضجة الناتجة من الانقسام الاختزالي الثاني. والبيض المتفلج الذي يحتوي على نواتين فقط هو الذي ينمو بشكل سليم والبقية تنتج أجنة غير سليمة.

21. 2: The nucleus of polar body to obtained the double number of chromosomes (2n) نواة الجسم القطبي للحصول على العدد الثنائي للكروموسومات It is known that eggs contain half the number of chromosomes (1 n). So how can the eggs with a haploid set (1 n) of chromosomes become a diploid chromosome sets (2n). The nucleus of the polar body is alternative of the male nucleus. When meiosis occurs, the second polar body separated from the egg and then come back and merge with the nucleus of the egg nucleus to complete the binary number of the chromosomes.

22. This explains to us, that embryos resulting from eggs parthenogenesis in lizards are always female, because eggs contain sexual chromosome X only. When the egg is meiosis divided and then merge the egg with the polar body, back to form female (XX).
As well as, the parthenogenesis in birds eggs, turkey produces males only, and birds differ from mammals, the sexual chromosome structure of male is (ZZ) and female is (ZW), When meiosis division is occurs the one chromosome going to the egg and other to polar body.

23. If the secondary egg take the chromosome Z and complete the second meiosis division to produce the mature egg and second polar body and did not separate or back to merge with the nucleus of second polar body to produce ZZ or WW. WW doesn't complete the growth because chromosome W like chromosome Y not contains the essential genes for growth or development.