The sporozoite, schizont and trophozoites are asexual stages, whereas gametocytes, zygote, ookinetes and oocyst are the sexual stages in the lifecycle of Plasmodium.

1. Shri Shivaji Education Society, Amravati's
Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly. Dist. Buldana
Topic: Sexual Life Cycle of Plasmodium vivax
Class: B.Sc-I, Sem-I
Shantaram Bhoye
Assistant Professor
M.Sc., NET-JRF, SET, M.A.(Eng.)

2. Sexual cycle or sporogony:
 Its occurs in the alimentary canal of female Anopheles mosquito.
1) Transfer of gametocytes to mosquito:
 When female Anopheles mosquito sucks the blood of infected person (malaria patient), that
time along with blood, RBC containing the male and female gametocytes enter into
alimentary canal of mosquito.
2) Gametogony or Gametogenesis:
 In stomach of mosquito the RBC rupture and gametocytes are set free.
 The gametocytes now undergo process of gametogenesis to form gametes.
a) Formation of male or micro-gametes:
 Inside the stomach of female Anopheles mosquito microgametocyte become very active.
 Its nucleus divides mitotically into 6 to 8 haploid daughter nuclei.
 One nucleus migrates into each cytoplasmic process.
 These nucleated process are the microgametes or male gametes.
 Each microgamete measures 20 to 25μ in length.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

3.  Formation of microgametes is so sudden and violent or explosive that known exflagellation.
 Soon microgametes separate from the residual cytoplasm of gametocyte and start moving actively in stomach
of mosquito, in search of female gamete.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

4. Formation of female or macro-gametes:
 Female or macro-gametocyte some reorganization and becomes female gamete or macro
gamete.
3) Fertilization:
 Female gamete or macro gamete gives out a small cytoplasmic projection, known as cone
of reception or fertilization cone.
 The nucleus of macrogamete comes to near its receptive cone.
 When lashing microgamete comes in contact with macrogamete enters through receptive
cone into female gamete and takes place fertilization or syngamy.
 Complete fusion of nuclei and cytoplasm of two gametes occur resulting in formation of
zygote known as fusion nucleus or synkaryon.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

5. 4) Ookinete:
 Zygote remains rounded and motionless for some time, but soon it becomes
elongated, vermiform (worm like) and motile known as vermicule or ookinete (active
egg).
 It performs wriggling or gliding movement.
 It measures about 15-22 μ in length and 3 μ in width.
 By pointed end it bores through epithelial linings of mosquito stomach, enters cell
and later rests against basement membrane of stomach.
 Now ookinete stops to move, becomes spherical and begins to encyst.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

6. 5) Encystment and formation of oocyst:
 The ookinete after coming out of the mosquito stomach.
 The ookinete now becomes spherical and begins to
encyst.
 The cyst wall is thin, membranous and elastic.
 Encysted zygote known as oocyst.
 This oocyst grows in size absorbing nourishment from
surrounding medium.
 50 to 500 such oocysts can be seen bulging as tiny
nodules from outer wall of stomach.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

7. 6) Sporogony:
 Each oocyst divide by asexual method known as sporogony.
 Oocyst is diploid.
 Nucleus divide first by meiosis and then repeated mitosis, forming large number of haploid
daughter nuclei.
 The daughter nuclei come to lie along free margins of cytoplasmic masses.
 In this way about 10,000 minute, slender and sickle shaped sporozoites are formed from single
oocyst.
 When oocyst bursts these sporozoites are liberated into haemocoel (body cavity) of the mosquito.
 They are motile, they move to different organs in the body of mosquito, but many penetrate into
the salivary glands.
 In mosquito, the whole cycle is completed in 2 to 4 weeks depending upon temperature.
 The mosquito now becomes infective.
 The salivary glands of single infected mosquito may contain as 2,00,000 sporozoites.
 When bites a healthy person, along with saliva thousands of sporozoites are injected in his blood
and starts the cycle again.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana