Reproductive Systems

Reproductive Systems

Reproductive Systems3-D male reproductive System3-D female reproductive System

Testes TissueSperm production occursin seminiferous tubules

See Fig. 46.122

Testes TissueSperm production occursin seminiferous tubules

At puberty, testosterone production begins in interstitial cells

See Fig. 46.123

Testes TissueSperm production occursin seminiferous tubules

Sertoli cells regulatesperm production & nourish developing sperm

See Fig. 46.124

Testes TissueSperm production occursin seminiferous tubules

Spermatozoa are produced by spermatogonia

See Fig. 46.125

Fig. 46.11

Animation: Spermatogenesis

Spermatogenesisproduction of sperms occurs in the testes in seminiferous tubulesfirst stage of spermatogenesis mitotic cell divisions of primordial germ cells to produce spermatogonial cells spermatogonial cells then undergo a period of growth to form primary spermatocyteseach primary spermatocyte then undergo two meiotic cell divisions:meiosis I to produce secondary spermatocyte & meiosis II to produce spermatids spermatid cells then undergoes differentiation to form sperm cells Sperm cells are nourished by Sertoli cells each primary spermatocyte produce 4 sperm cells with haploid number of chromosomes i.e. 23 chromosomes

Structure of the sperm

Animation: OogenesisOogenesisoogenesis is process by which female gametes (egg cells) are produced in the ovary it begins during fetal development when oogonia are formed from primordial germ cells by mitosisOogonia undergoes growth to form primary oocytesprimary oocyte begin first meiotic division but stop in Prophase I until on set of pubertyat puberty some follicles develop each month in response to FSH produced by pituitary glandprimary oocyte completes first meiotic division to forms two cells of different sizes due to unequal distribution of cytoplasmthe one with less cytoplasm become the first polar body which eventually degeneratesthe larger cell becomes secondary oocyte and proceeds to meiosis II & stops at prophase IImeiosis II is completed if cell is fertilized forming an ovum and second polar body

structure of the ovumAnimation: Comparison of Spermatogenesis and Oogenesis

Comparison Between spermatogenesis & oogenesisspermatogenesisoogenesismillions sperms produced per dayfour sperms of equal division of the cytoplasm & no polar bodiesbegins at puberty i.e. at sexual maturityoccurs throughout adult lifesperms are produced continuously & released during ejaculationoccurs in the testesspermatogenesis involves meiotic cell divisionproduce haploid cells

one ovum per 28 day menstrual cycleone ovum, unequal division of the cytoplasm, 2 polar bodiesbegins during foetal developmentends at menopauseovum released during ovulation in the middle of the menstrual cycleoccurs in the ovaries oogenesis involves meiotic cell divisionproduce haploid cells

Fertilisationsperm cell approach the egg in oviductAcrosome of sperm cell releases hydrolytic enzymes which digest jelly layer (zona pellucida) of the eggsperm cell head (acrosomal process) extends through jelly to vitelline membrane (eggs plasma membrane)binding proteins on surface of acrosome attach to receptors on vitelline membranesperm plasma membrane fuses with egg plasma membranefusion of plasma membranes causes depolarization of egg plasma membrane i.e. cortical reaction which bars other sperm cells from fusing with membrane sperm nucleus enters egg (secondary oocyte) after dissolution of nuclear membranes resulting in combination of genetic material

Revision QuestionsDraw a labelled diagram of the adult female reproductive system. [4] Draw a labelled diagram of an adult male reproductive system. [6 ]Explain the processes involved in oogenesis in humans. [9]Draw the structure of a mature human egg. [4] Explain the role of hormones in the regulation of the menstrual cycle in human females. [8]Draw a labelled diagram of a mature sperm. [5]Outline the process of spermatogenesis in humans. [5]Compare the process of spermatogenesis and oogenesis. [7]Describe the process of fertilization in humans. [8]Describe the development of the early human embryo. [5]Outline the regulation of pregnancy by two named hormones. [4]