Reproduction and Development

• Asexual reproduction - Mode of reproduction that does not involve the use of gametes or sex cells
• Fission - Type of asexual reproduction involving the division of body into two or more equal parts. (e.g paramecium and amoeba)
• Fragmentation - Type of asexual reproduction where the body breaks into two or more parts, with each fragment capable of becoming a complete individual; in animals, fragmentation is usually followed by regeneration where the missing parts are produced. (e.g. starfish)
• Budding - Type of asexual reproduction where a new individual arises as an outgrowth (bud) from its parent, develops organs like those of the parent, and then detaches itself. (e.g hydra)
• Sporulation - Type of asexual reproduction where new individual forms from an aggregation of cells surrounded by a resistant capsule or spore, which later on germinates (e.g fungus)
• Parthenogenesis - is a form of asexual reproduction by self-impregnation resulting in the production of a zygote from an unfertilized egg. (e.g. scorpions)
• Sexual reproduction - Mode of reproduction that involves the use of gametes or sex cells
• Conjugation - is a form of sexual reproduction in bacteria. Two individual cells are united by a tube formed by outgrowths from one or both cells. Genetic material from one cell (designated the male) then passes through the tube to unite with genetic material in the other cell (designated female).
• Isogamy - Fusion of similar gametes which are usually motile
• Heterogamy - Fusion of dissimilar gametes. In oogamy, a large immotile gamete, the egg is fertilized by a small motile gamete, the sperm.
• Bisexual reproduction - Type of sexual reproduction involving the union of gametes from two genetically different parents
• Hermaphrodite - An individual with both male and female reproductive tissues. In animals “self-fertilization” is not common. In worms, a hermaphrodite needs a male to donate sperms in order to fertilize the oocytes in its body.
• Gametogenesis - is the process by which diploid precursor cells undergo meiotic division to become haploid gametes (sex cells)
• gametogenesis in females is called oogenesis and produce ova (eggs)
• gametogenesis in males is called spermatogenesis and produce spermatozoa (sperm)
• The process of gametogenesis occurs in the gonads
• Spermatogenesis - describes the production of spermatozoa (sperm) in the seminiferous tubules of the testes
• These cells (spermatogonia) then undergo a period of cell growth, becoming spermatocytes.
• The spermatocytes undergo two meiotic divisions to form four haploid daughter cells (spermatids)
• The spermatids then undertake a process of differentiation in order to become functional sperm cells (spermatozoa)
• Oogenesis describes the production of female gametes (ova) within the ovaries
• Fertilization is a stage of development that results in a unicellular diploid zygote.
• Cleavage - is a stage of development involving a series of mitotic divisions to produce a multicellular blastula from a unicellular zygote.
• Gastrulation is a stage of development involving morphogenetic movements of the cells to produce a gastrula with distinct germ cell layers.
• Germ cell layers - These layers with give rise to specific tissues and organs.
• In vertebrates, germ cell layers consists of three layers; ectoderm, mesoderm, and endoderm.
• ectoderm - Nervous system (brain and spinal cord), epidermis, sense organs
• mesoderm - muscles, bones, cartilage, circulatory, excretory, and reproductive organs
• endoderm - digestive and respiratory organs, endocrine glands, germ cells and gametes
• mesoglea - not a true cell layer as cell arise from other layers
• Growth - is a stage of development characterized by an increase in size of an individual.
• Development is terminated by death.
• reproductive system - system involved in the production of offspring
• The female reproductive system has the following functions: 1. Production of female sex cells 2. Reception of sperm cells from the male

  3. Nurturing the development of and providing nourishment for, the new individual
• The internal reproductive organs of the female are located within the pelvis, between the urinary bladder and rectum.
• ovaries - It is suspended in the pelvic cavity by a ligament.
• The ovary contains ovarian follicle, which contains an oocyte, the female germ cell.
• fallopian tubes - This part extends from the area of the ovaries to the uterus.
• Long, thin processes called fimbriae surround the opening of each uterine tube.
• fundus - The part of the uterus superior to the entrance of the uterine tubes.