Human Reproductive System

External fertilization occurs when gametes are released into the environment, typically water, for fertilization. Frogs and fish commonly exhibit this behavior, whereas mammals and birds typically use internal fertilization.

Calcium ions are released upon fertilization, triggering a wave of metabolic activity in the egg, including increased respiration and protein synthesis.

Ureter is a part of excretory system it carries urine from the kidney to the bladder.

In In-Vitro Fertilization (IVF), commonly known as the test-tube baby process, the fertilization of the egg by the sperm occurs outside the mother's body in a laboratory setting before the embryo is implanted.

After a female egg is fertilized, it is known as a zygote. Once the egg is fertilized, the zygote begins a two-week period of rapid cell division and will eventually become an embryo.

Leydig cells are found in the testicles next to the seminiferous tubules, where sperm is produced within the testes. Leydig cells are also known as interstitial cells of Leydig. Leydig cells play a vital role in maintaining proper levels of male hormones, including testosterone.

Ejaculation is the expulsion of seminal fluid from the urethra of the penis during orgasm. So, sperms are released by the ejaculation.

Vasectomy is a method of male sterilization in which a portion of the vas deferens is removed. It is a surgical procedure during which the vas deferens the tubes that carry sperm from the testes  are severed. Vasectomy is a very safe and permanent means of male contraception, though it can be reversed should the need arise.

Fertilization occurs in oviduct. It is a either of a pair of long narrow ducts located in the human female abdominal cavity that transport the male sperm cells to the egg & provide a suitable environment for fertilization, and transport the egg from the ovary, where it is produced, to the central channel (lumen) of the uterus.

The vas deferens is a narrow tube of the male reproductive system that carries sperm from the epididymis into the body. There are two such tubes, each located on the sides of each testicle. Each tube is about 11.8 inches (30 cm) long and is composed of smooth muscle.

The testicles (also called testes) are part of the male reproductive system. The testicles are two oval organs about the size of large olives. They are located inside the scrotum, the loose sac of skin that hangs behind the penis. The testicles make the male hormones, including testosterone, and produce sperm.

Spermatogenesis is the process of producing sperm with half the number of chromosomes (hapliod) as somatic cells.The germ cells progress first from the diploid to haploid state and then change shape to become spermatozoa.The process of spermatogenesis then allows the recombination of male and female haploid gametes at fertilization..Spermatogenesis occurs in medullary sex cords known as seminiferous tubules.

The failure of descending of testes into scrotum is termed as cryptorchidism.

Double fertilization is a characteristic process in angiosperms where one male gamete fuses with the egg to form a zygote, and the other fuses with the secondary nucleus to form the primary endosperm nucleus.

The fusion of one male gamete with the two polar nuclei (or the secondary nucleus) results in the formation of the primary endosperm nucleus (PEN), which is triploid.