REPRODUCTIVE SYSTEM Both asexual and sexual reproduction occur in the animal kingdom. Asexual reproduction involves the formation of individuals whose genes all come from one parent. There is no fusion of sperm and egg. o Eg. Binary fission, budding, fragmentation, parthenogenesis Sexual reproduction is the formation of offspring by the fusion of haploid gametes. o Ovum: female gamete - usually large and non-motile. o Internal and external fertilization both depend on mechanisms ensuring that mature sperm encounter fertile eggs of the same species. External fertilization: requires moist habitat that will protect a developing egg from desiccation and heat stress. Internal fertilization: requires cooperative behavior that leads to copulation. Pheromones: chemical signals released by one organism that influence the behavior of other individuals of the same species. Spermatozoon: male gamete - Species with internal fertilization usually produce fewer zygotes but provide more parental protection than species with external usually small and motile. fertilization. Hermaphroditism: individuals have both male and female reproductive systems. o Eg. Clownfish, earthworms, slugs Gonochorism: sexes are separate INTERNAL Produce fewer zygotes More parental protection In birds, reptiles and monotremes, eggs are protected by calcium and protein shells Brooding: eggs develop to planula stage in gastrovascular cavity of parent polyp Broadcast Spawning: eggs and sperm are shed into the water column where fertilization and development occurs EXTERNAL Produce more zygotes Survival rate is lower In fishes and amphibians, eggs are surrounded by a gelatinous coat In mammals, the embryo is retained within the female’s reproductive tract Complex reproductive systems have evolved in many animal phyla. The least complex reproductive systems lack gonads. Eggs and sperm develop from undifferentiated cells lining the coelom in polychaete worms. Sequential hermaphroditism: individual reverses its sex during its lifetime Protogynous: female to male Protandrous: male to female Parthenogenesis: egg development without fertilization. Eg. Aphid, daphnia, honeybee, whiptail lizard, Komodo dragon, hammerhead shark Fertilization: union of sperm and egg Most insects have separate sexes with complex reproductive systems. In many species, the female reproductive system includes a From the seminiferous tubules sperm pass to the spermathecal, a sac in which sperm may be stored for a year or more. coiled tubules of the epididymis. It takes about 20 days for sperm to pass through the tubules of the epididymis. The sperm become motile and gain the ability to fertilize. Semen: also known as seminal fluid; contains mucus, fructose, a coagulating enzyme, ascorbic acid and prostaglandis. In many non-mammalian vertebrates the digestive, excretory and reproductive systems share a common opening to the outside, the cloaca. Mammals have separate opening for digestive and reprodutive systems. MALE Gamete: sperm Gonad: testes Gametogenesis: spermatogenesis Set of haploid/ chromosomes: monoploid FEMALE egg ovary oogenesis haploid/ monoploid Ejaculation: propels sperm from the epididymis to the vas deferens. The VD runs from the scrotum and behind the urinary bladder. Each vas deferens joins with a duct from the seminal vesicle to form an ejaculatory duct. The ED open into the urethra. The urethra drains both excretory and reproductive system. Spermatogenesis: the production or development of mature spermatozoa. Male Reproductive System - - Consists of a pair of testes accompanied by a set of excretory ducts as well as other accessory glands. Its main purpose is to produce sperm. Bull, Ram, Stallion, Boar Seminiferous Tubules: site of the germination, maturation, and transportation of the sperm cells within the male testes. Hormones involved in Spermatogenesis Gonadotropin Releasing Hormone (GnRH) Follicle Stimulating Hormone (FSH) Interstitial Cell Stimulating Hormone The penis is composed of three layers of spongy erectile tissue. During sexual arousal the erectile tissue fills with blood from arteries. The resultant increased pressure selas off the veins that drain the penis. The penis of some mammals possesses a baculum, a bone that helps stiffen the penis. (ICSH) also known as Luteneizing Hormone (LH) Testosterone Inhibin Effects of Testosterone muscle and bone growth facial and pubic hair growth thickening of vocal cords Ovarian Cycle: refers to the series of changes growth of pharyngeal cartilage hair follicle effects in the ovary during which the follicle matures, the ovum is shed and the corpus luteum develops. stimulates sebaceous glands Female Reproductive System - Oestrous Cycle: sequence of hormonal changes that occurs through the ovarian cycle. These changes influence the behavior and body changes of the female. It facilitates the fertilization of the egg and sperm cells as well as supporting the development of the offspring during - pregnancy. Cow, Ewe, Mare, Camel, Sow Hormone Fluctuation Oogenesis: the production or development of an ovum.