Frequently, when we consider how species reproduce, we consider the nearby animals, such as people, dogs, cats, lizards, dragonflies, and dogs. When these animals mate, the egg and sperm do not meet outside in the water or the air, but rather inside the body.
Since many gametes cannot float through the air the way they can float through water, internal fertilization developed as a result of the transition to land. In some species of animals, the egg and sperm meet inside the male, despite the fact that this is typically where they do. The majority of sperm are motile, or able to move around inside the body in quest of an egg to fuse with.
This makes the majority of mammals, a few cartilaginous fish, and a few reptiles viviparous. The benefit of internal fertilization is that it prevents the fertilized egg from becoming dehydrated on land. The female’s isolation of the embryo prevents the young from being preyed upon.
Either sex may have sex organs that can facilitate the meeting of sperm and egg in internal fertilization. In mammals, the female vagina receives an organ known as the penis. The majority of male insects also have an aedeagus, a lengthy organ that functions quite similarly to the penis. In a unique kind of bug known as a Neotrogla, the roles are switched. A gynosome, which the female has, functions as a kind of penis to push sperm from the male. A unique organ termed a spermatheca, which is found in most female insects and some other species of animals, is used to store sperm. Sperm can be kept in the spermatheca for many years and used as needed.
Sperm and egg combine inside the ovary in plants. Pollen, which is small and light and may float on the water or in the air, is the source of sperm. However, plants can possess sex organs that facilitate the union of sperm and egg. Floral petals entice pollinators, and the stigma, a flower component, collects pollen and directs it to the ovary.
Internal Fertilization Among Pregnant Moms
Although it may seem unusual, for the first week or two of the pregnancy period, you are not actually pregnant. Yes, you did read that right.
Usually, conception starts about two weeks following the start of your previous menstruation. Your doctor will add 40 weeks to the start of your last period to determine your anticipated due date. This means that even though you weren’t pregnant at the time of your period, it is included in the calculation of your pregnancy.
The sperm and egg combine in one of your fallopian tubes to create a zygote, a single cell organism. You may have multiple zygotes if more than one egg is discharged and fertilized or if the fertilized egg divides into two.
23 from the biological mother and 23 from the biological father make up the zygote’s average 46 chromosomes. These chromosomes contribute to the sex and physical characteristics of your child.
The zygote moves down the fallopian tube and toward the uterus shortly after fertilization. It will start dividing at the same time to produce a morula, a group of cells that resembles a small raspberry.
The blastocyst, a rapidly dividing ball of cells, has started to penetrate the uterine lining (endometrium). Implantation is the name of this process.
The inner group of cells within the blastocyst will develop into the embryo. Part of the placenta, which will sustain your unborn child during your pregnancy, will develop from the outer layer.
The blastocyst begins to release HCG hormone in the third week following conception, or the fifth week of pregnancy. This instructs your ovaries to start producing more estrogen and progesterone instead of releasing eggs. Increased levels of these hormones cause the placenta to expand faster and stop your period, which is frequently the first sign of pregnancy.
Three layers now make up the embryo. Your baby’s outermost layer of skin, eyes, inner ears, central and peripheral nervous systems, and ectoderm all develop from this top layer.
The mesoderm, the intermediate layer of cells, is where your baby’s heart and rudimentary circulatory system will develop. The bones, ligaments, kidneys, and a large portion of the reproductive system of your unborn child will all be built on top of this layer of cells.
The lungs and intestines of your unborn child will develop in the inner layer of cells called the endoderm.
Growth is rapid this week. Your baby’s neural tube is closing just four weeks after conception. The neural tube will allow the baby’s brain and spinal cord to develop.
Other organs, including the heart, are also beginning to develop.
The development of the structures required for the eyes and ears. There are little buds that will shortly develop into arms. The body of your unborn child starts to curve in a C pattern.
Your baby’s brain and face are developing at seven weeks into your pregnancy, or five weeks following conception. The beginnings of the retinas and depressions that will become nostrils are also apparent.
Leg-forming lower limb buds are visible, and the paddle-shaped arm buds from the previous week have now grown.
Your baby’s lower limb buds start to resemble paddles six weeks after conception, or eight weeks into your pregnancy. A finger has started to form. The eyes are evident, and there are little swellings defining the future shell-shaped portions of your baby’s ears. The nose and upper lip have developed. Straightening of the neck and trunk can be seen.
Your baby’s arms expand and elbows show seven weeks after conception, during the ninth week of pregnancy. Eyelids begin to develop and toes are apparent. Despite having a huge head, your infant still has an undeveloped chin.
Your baby’s head has rounded out by the tenth week of pregnancy, or eight weeks following conception.
Your child’s elbows can now be bent. Fingers and toes get longer and lose their webbing. The external ears and eyelids are still growing. It is easy to see the umbilical cord.
Your baby’s head still makes up almost half of its length at the beginning of the eleventh week of pregnancy, or the ninth week following conception. The body of your baby is starting to catch up, though.
The medical term for your child is currently a fetus. Your baby’s face is broad, its eyes are widely spaced, its eyelids are fused, and its ears are low-set this week. Future tooth buds start to erupt. Your baby’s liver is starting to develop red blood cells. Your baby’s external genitalia will begin to transform into a penis or clitoris and labia majora by the end of this week.
Your unborn child is growing fingernails ten weeks after conception, or at twelve weeks into your pregnancy. The profile of your baby’s face has grown more developed. The abdomen houses the person’s intestines.
A normal pregnancy is considered internal fertilization. As long as the process of fertilization takes place inside a creature’s body, it is considered internal fertilization.