Reproduction and Development

• Asexual reproduction - no fusion of gametes, only the production of genetically identical offspring
• binary fission - cell doubles its size then divides into two identical cells
• Budding - Asexual reproduction in which a new individual is produced from the parent plant by splitting off a small part of the parent plant
• fragmentation - parent organism is separated into parts which grow into whole organisms themselves
• sporulation - a new individual forms from an aggregation of cells surrounded by a resistant capsule
• sexual reproduction - the fusion of male and female gametes to form a zygote
• isogamy - gametes have the same morphology
• heterogamy - gametes are physically different
• oogamy - advanced form of sexual reproduction in which the male and female gametes fuse together
• reproductive system - the organs that produce and carry out the process of reproduction
• parthenogenesis - egg is fertilized by the sperm of the mother
• hypothalamus releases gonadotropin-releasing hormone (GnRH)
• Gonadotropin-releasing hormone increases the production of follicle stimulating hormone

  (FSH) and luteinizing hormone (LH)
• FSH and LH are present in both males and females
• Follicle Stimulating Hormone (FSH) is released by the pituitary gland and stimulates the ovaries to produce oestrogen
• follicle stimulating hormone promotes sperm production
• follicle stimulation hormone stimulates follicle growth
• luteinizing hormone stimulates testosterone and production and secretion
• luteinizing hormone stimulates estrogen and progesterone production
• when testosterone levels are high, the production of FSH and LH decreases
• SPERMATOGENESIS - formation and development of sperm cells
• outer edge of seminiferous tubules contain stem cells that will produce sperm
• sperm production is inward
• Spermatogonia → primary spermatocyte → secondary spermatocyte → spermatid → sperm
• mature sperm is released to the lumen
• OOGENESIS - development of the ovum (egg cell)
• Oogonia: mitotically divide and starts meiosis I, resulting cell is called a primary oocyte
• Primary oocyte: stops at prophase I
• Secondary oocyte: proceeds to meiosis II but stops at metaphase; released at ovulation
• Meiosis II resumes if a sperm fertilizes it
• ovarian and uterine cycles are closely related
• ovarian cycle → development of follicles in the ovary
• uterine cycle → development of the endometrium in the uterus
• Gonadotropic hormone levels and ovarian hormone levels regulate the processes in the two cycles
• The ovarian cycle consists of two phases: follicular and luteal
• Progesterone maintains and sustains the endometrium.
• Follicles secrete estrogen
• Theca cells produce androstenedione → passed to granulosa cells → converted to estrogen
• UTERINE CYCLE - also known as the menstrual cycle in humans and other primates
• menstruation → shedding of the stratum functionalis (outer layer) of the endometrium (lining of uterus) if mature egg is not fertilized