|Original (French) Title||Naissance|
|The Cell Planet||The Body's Sentinels|
Birth is the second episode of Once Upon a Time... Life. It focuses on fertilization, pregnancy and birth process.
| Spoiler warning!|
This article contains plot details about an upcoming episode.
Sperm cells make their way through uterus and the Fallopian tubes, with most of them dying on their way. They soon reach the egg cell and break the barrier separating them from it. One of them finds the hidden entrance and uses its laser to open it. As soon as it's halfway through, the entrance closes, snapping its tail and disappears. Once inside, the Spermatozoon navigates through cytoplasm, reaches the nucleus and deploys the homologous Chromosomes. Chromosomes pair up and begin to dance, with sex pair forming as well (Chromosome Y). Then, the egg cell begins cell division, splitting many and many times, and soon reaches the uterus. Cervix closes to preserve the zygote and soon it is formed into an embryo, with placenta forming as well.
In one of cells, Maestro becomes disappointed with the central asking his cell specifically to give great help in manufacturing future tissues, knowing that all cells need to work as a team to create a human being. He contacts the Chromosomes central and orders them to coil up for mitosis. During the quick hassle in DNA coiling, an Adenine base almost causes substitution when it tries to match with Cytosine, but is noticed by an Enzyme and expelled from the chain. Soon, all the Chromosomes are coiled and mitosis begins. Soon, many essential cells (e.g. muscle cells, eye cells, heart cells, brain cells, bone cells etc.) are being created from mitosis. They head from their creation site to the platforms they were assigned to and are helped by Neutrophil Granulocytes.
Soon, cardiac tissue is created and embryo becomes a fetus. Then, it is shown how bone cells create future tissue for the skeleton. In the meantime, eye cells are given an aid while en-route to the eye sockets. Then, the leader separates the cells in units for the cornea, retina, crystalline lens etc. During the tissue formation, the leader requests an Interferon, asking for nourishment for the cells, specifically collagen and ovalbumin. Maestro commands the Enzymes to prepare the mRNA for protein synthesis. After synthesis is over, the Proteins are deported to Golgi Bodies, from where they make their way to the bloodstream. When they reach the heart cells, an Enzyme lets them in. The mentioned cells begin finishing the cardiac tissue.
The rest of the episode consists of a montage showing the growing fetus, along with receiving all necessary nutrients for body. Then, the process of birth is shown. The newborn gets checked for respiration and is given to his mother.
- This is the first episode to feature a process happening in an adult human in the series.
- This is the debut episode of Chromosomes.
- The "genetic accident" mentioned by the Enzyme during preparations for prophase was specifically substitution, a condition under which the nitrogenous bases are mismatched.
- Cells for the tissues were assigned specific platforms:
- Eye cells - 47
- Muscle cells - 10
- Bone cells - 17
- Heart cells - 22/19
- Liver cells - 8
- Skin cells - 40
- During the creation of eyes, tissue for iris is made using the muscle cells; not eye cells.
- This is the first episode to show a detailed protein synthesis and Uracil nitrogenous base.
- This episode focuses on four main topics, out of which one has slight connection with topic of the entire episode:
First topic - Fertilization Edit
- The definition of fertilization is that it presents fusion of male and female gametes, with their nuclei fusing in the process. The result of fertilization is zygote, that, in a set of very complex processes, grows into a new organism.
- The benefits of fertilization under normal circumstances:
- A diploid karyotype is created, which ensures the offspring to have the same number of chromosomes as its parents.
- In a sense of complete coincidence, fusion of random gametes creates a large diversity.
- Fertilization defines the very sex of an organism (combination XX for female, combination XY for male).
- It initiates mitosis which develops the zygote into an embryo.
Second topic - Mitosis Edit
- (Though it's a cells related topic, this episode is the first one to feature cell divison) Mitosis presents one of two major types of cell divison, where a diploid mother cell divides in two identical, also diploid daughter cells.
- Mitosis consists of four main phases:
- Metaphase: chromosomes line up in metaphase plate. Spindle fibers projected by centrioles are attached to their centromeres and prepare to pull them apart. The nuclear membrane is completely gone at this point.
- Anaphase: spindle fibers pull the daughter chromatids apart, forming a diploid number at each pole.
- Telophase: centrioles contract their spindle fibers. New nuclear membranes form and surround the divided karyotypes. Cytoplasm slowly divides and the cleavage furrow appears.
Third topic - Gestation Edit
- Gestation, commonly known as pregnancy, is a period during which a female organism carries a developing offspring. It lasts nine months in humans, and also can develop more offspring, creating twins.
- By the end of gestation, an average human offspring weighs about 3.2 kg (7.05 lbs) and is 50 cm (19.69 in) long.
- Normal gestation lasts nine months, respectively approx. 40 weeks or 280 days. If gestation should stop before the half of seventh month (can be achieved both biologically and mechanically), the result is an abrupt ending called abortion, which ends in the death of fetus.
Fourth topic - Birth Edit
- Birth presents the end of woman's pregnancy and the fetus ultimately leaving her uterus, either through vaginal delivery or through caesarean delivery.
- Birth contains three phases and is initiated by hormones:
- Cervical dilation — to make enough room for the infant to make its way out of the uterus and through the vagina, the cervix has to stretch to be wide enough for the infant to get through. It can stretch open to 10 cm in its complete dilation phase, during which infant slowly makes its way into the vagina. Given the fact that it has to pass, woman's pelvis takes a lot of pressure to endure the passing of the offspring.
- Expulsion — the infant is making its way through the vagina during which woman endures a large pressure on pelvic area. At the beginning of the normal second stage, the head is fully engaged in the pelvis; the widest diameter of the head has passed below the level of the pelvic inlet. The fetal head then continues descent into the pelvis, below the pubic arch and out through the vaginal introitus. The time needed for expulsion varies from one woman to another.
- Delivery of placenta — process of birth officially ends when the walls of uterus expel the placenta along with umbilical cord.