Bio Room

  What is oogenesis ? Gametogenesis in females ,which causes formation and maturation of  female gametes (ovum ) is called oogenesis .  Oogenesis occurs in the ovary of females and begins before birth in female ( spermatogenesis occurs at puberty). Oogenesis is divided into three stages, these are 1) multiplication phase                   2) growth phase                    3) maturation phase  Multiplication phase- During fetal stage of development,  primodial germ cell originated in endoderm of yolk sac migrates to ovaries .  Some cells are divided mitotically to form oogonia also known as egg mother cells . Approximately 20 lakh oogonia are present in each ovary . It enters growth phase  Growth phase- In this phase growth of oogonia occurs . Oogonia drives nutrients from surrounding follicular cells and converted in to primary oocyte .  ...

What is gametogenesis ? The formation and development of gametes is known as gametogenesis . The male gametes i.e sperm and female gametes i.e ovaum or ova , are formed and mature in gametogenesis process.  Organisms bears only two types of cells  1. Somatic cells or body cells and 2. Gametic cells or sex cells  Mitosis ( equational cell division)occurs in somatic cell . These cells contain diploid number of chromosomes(2n) . The sex cells are divided meiotically ( reduction division)  . They bears haploid number of chromosomes (n).  The process of development of gametes are different in male and female.  Male gametes are formed and developed in the process called spermatogenesis and female gametes in oogenesis . Spermatogenesis   The process by which production and maturation of male gametes i.e sperm occurs is called spermatogenesis .  This process occurs in the seminifrous tubule of testes . Formation of sperms takes place from...

 The female reproductive organs contains a pair of ovaries ,paired oviducts ( fallopian tubes ), single uterus and external organs collectively called vulva . Ovaries are the primary sex organs and others are female accessory ducts .  The ovaries secretes female sex hermones and also  produce female gametes ova , the ova transport in to the fallopian tube for fertilization by sperm , implantation and development of fetus occurs in uterus , the vagina receives penis during sexual intercourse , act as a passage for menstrual flow and also the passage for child birth . Ovaries   These are a pair of primary female reproductive organs.  The ovaries are located in a shallow depression in each side of uterus called ovarian fossae and  held in position within peritoneal cavity by several ligaments anchors ovary medially to the uterus .  The ovary have three parts: germinal epithelium, tunica albuginea, and ovarian stroma. The germinal epithe...

 Reproductive system  Sexually reproducing animals possess a functional reproductive system . Animals which are having both male and female reproductive structures for e.g. in liver fluke, tape worm and earth worm are called monoecious animals on the other hand animals which are having separate reproductive structures in both male and female is known as dioecious animals . Humans are dioecious animals i.e both sexes are separate. The reproductive system of human consists of  1. Primary sex organs 2. Secondary sex organs  3. Accessory sex organs  The primary sex organ produses gametes  , testis in males and ovary in females . It also secretes sex hermones . Secondary sex organs consists of  prostate, seminal vesicle, vas defferens and penis in male . The female Secondary sex organs  consists of fallopian tube, uterus, vagina and mammary gland. These are have important functions in reproduction.  Accessory sex organs distinguish between m...

Implantation: The attachment of the blastocyst to the uterine wall is known as Implantation . This process starts 5- 6 days after fertilization. The inner cell mass of blastocyst in placed against endometrium ,the inner most layer of uterus.  The trophoblastic cell break the endometrium at the point of contact and the blastocyst sinks into a pit formed in endometrium.  Finger like projections (villi) are formed in the contact point in order to supply nutrients from mother to the developing embryo through placenta .  Chorion is also developed from tropoblast cells ,which secret human chorionic gonadotropin (HCG) hermone which maintains and stimulates the corpous leuteum to secrete progesterone hermone which prepares the endometrial wall for implantation and growth of the developing embryo.  Function of placenta- Placenta is like a lifeline for the developing one which helps in various way to sustain life in the womb. 1. The oxygen and required nutrients are transm...

Cleavage in human embryo: After the fertilization process is done the resulting zygote undergoes rapid and  repeated mitotic division which result in the formation of bunch of small cells . This process in known as cleavage .  Cleavage is different from normal cell division in which the cells become smaller and smaller but the total volume of the embryo remains constant.  Cleavage of the zygote occurs in the fallopian tube of the uterus.  It takes 30 hours to complete the first cleavage which divides  the single celled zygote longitudinally in to two blastomeres of un equal size and then followed by another division after 10 hour from the 1st cleavage in right angle to the plane of 1st cleavage resulting in to four blastomeres . During early cleavage the embryo slowly moves towards uterus.  Morula stage-   In fourth day the embryo reaches the uterus during this the embryo reches 16- 32 called stage called morula ,  This is the solid mass of cell ...