Animal Reproduction. By: Madison Allen.
By: Madison Allen
In sexual reproduction, the fusion of haploid gametes forms a diploid cell, the zygote. The animal that develops from a zygote can in turn give rise to gametes by meiosis. The female gamete, the egg, is a large, nonmotile cell. The male gamete, the sperm, is generally a much smaller, motile cell.
Many invertebrates can reproduce asexually by fission, the separation of a parent organism into two individuals of approximately equal size.
Hermaphrodism is when each individual has both male and female reproductive systems. Because each hermaphrodite produces as both male and female, any two individuals can mate.
Fertilization is the union of sperm and egg, which can be either external or internal.
In many insect species, the female reproductive system includes a spermatheca, a sac in which sperm may be stored for extended periods, a year or more in some species.
Ovaries – the female gonads are a pair of ovaries that border the uterus and are held in place in the abdominal cavity by ligaments (ovaries produce eggs and reproductive hormones)
Testes – consists of many highly coiled tubes surrounded by several layers of connective tissue, this is where the sperm is formedMale Reproductive Organs
Spermatogenesis – the formation and development of sperm, is continuous and prolific in adult malesSpermatogenesis
Oogenesis – the development of mature eggs, is a prolonged process in the human femaleOogenesis
Human gestation is divided into three trimesters of about three months each.