During labor, certain hormones are released that cause the contraction of the uterus in order to push the baby out. When those hormones are sensed by the glands of the endocrine system, they secrete more of that hormone which keeps labor going until the baby is born.

The endocrine system assists in maintaining and regulating different functions of the body by producing and discharging hormones. It comprises glands situated throughout the body, which produce chemicals known as hormones directly into the blood. The levels of hormones in the blood are monitored by a highly unique homeostatic mechanism known as feedback.  

The two kinds of feedback are common, that is, negative and positive feedback, of this positive feedback, is the rare mechanism. It augments the changes done rather than opposing them. For example, the discharging of oxytocin from the posterior pituitary gland at the time of labor is an illustration of a positive feedback mechanism.  

The stimulation of the muscle contractions, which pushes the baby via the birth canal is done by oxytocin. This discharging of oxytocin leads to an augmented or stronger contraction at the time of labor. This contraction is enhanced and intensify until the baby comes out of the birth canal. However, when the stimulus to the pressure receptor terminates, the generation of oxytocin ceases, which eventually results in the stopping of labor contractions.  

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.