How Baby Forms: A Tour from Male and Female Reproductive System to the Newborn Babies’ Birth.

Whether we have a glimpse on creations of the creator or scientific point of view, whenever we talk about formation of newborn babies, our thoughts point towards a single thing and that is “What a miracle of the creator!”. It’s what creates a desire to get in-depth knowledge of fetal development. All organisms on earth must have the ability to reproduce to survive. Reproduction is a process in which one organism produces another organism having characteristics from parents to offspring. That’s why, like other organisms, humans also have a reproductive system. The reproductive parts work together to produce sperms and eggs. In a process of understanding how babies form, one must know about male and female reproductive system. Let’s understand them one by one.

Male reproductive system

Male reproductive system comprises of four reproductive parts or genitals which are testicles, duct system, accessory glands and penis (Figure 1). All these parts work together for production and discharge of sperms into the female vagina.

Testicles

Testicles, also called testes, are oval-shaped glands present inside the scrotum. Testes produce sperms and male sex hormone testosterone. As a male reaches puberty, its testes start producing testosterone and sperms. Testosterone not only stimulate sperms production, but it also develops male characters like big muscles, dense voice, and facial hairs. In this way, testicles play an important role in production and storage of millions of sperms.

Duct system

Sperms produce in testes and transport to the duct system for maturation. Duct system has two important parts including epididymis and vas deferens. Epididymis is a coil-like tubular structure attach to both testes inside the scrotum. Sperms produce in testes and transfer to the epididymis tubes where they mature and store. Epididymis tubes convert at end into a long thin tube that transports sperms to the seminal vesicles. This thin tube is called vas deferens.

Accessory glands

Accessory glands play an important role in nourishment and movement of sperms during their transportation in the vas deferens. Male accessory glands include seminal vesicles and prostate gland. These glands secrete a specific fluid, the seminal fluid, that contains water and excessive nutrients necessary for nourishment and movement of sperms. The mixture of sperms and seminal fluid give rise to a semen. It plays an important role in fertilization process because it ensures movement of sperms from cervix to uterus and fallopian tubes in females.

Penis

Penis is the last organ of male reproductive system. Semen travels from vas deferens enters into the penis. Penis consists of two parts which include shaft and glans. Shaft is important part of penis, while glans is a tip or head of the penis of which semen or urine discharge from body through urethra. Penis is a spongy tissue from inside and it can contract/expand by increasing/decreasing blood pressure in the penis.

How do sperms produce?

At the time of birth in humans, small round cells are present in the tubular structure in testes inside the scrotum. These cells divide and convert into tadpoles due to production of testosterone hormone after puberty. Tadpoles have head in front and tail in the back and their head contains a genetic material. Tadpoles develop and convert into sperms which are key component of male reproductive system because human existence is impossible without sperms. Sperms after maturation in the epididymis move into the urethra through vas deferens and ejaculate and enter into the female body. In female body, sperms fuse with the female egg to form zygote that results in formation of embryo.

Female reproductive system

Female reproductive system or female genitals consists of external and internal reproductive organs or parts. External reproductive parts include vulva, mons pubis, labia and clitoris (Figure 2). Internal reproductive parts include vagina, cervix, uterus, fallopian tubes and ovaries. Like male genital organs, in pelvic region of females between the legs is present an outer covering which is called vulva. The vulva is a Latin word means covering. It covers vaginal and urethral opening in females. Inside the vulva and top of the vaginal opening is a fleshy area called mons pubis. It provides cushioning during sexual intercourse and secrete pheromones from sebaceous glands. Pheromones are chemical signals that provoke sexual attraction through behavioral response between males and females.

Similarly, on both sides of the vaginal opening are the skin folds or wavy structures. These folds are called labia or lips. Labia protect vaginal and urethral opening from irritation, infection and dryness. If we talk about structure of labia, it has opening in the center and close joint at top and bottom. There is a small sensory part, the clitoris, at the top joining position of the labia. Clitoris generates feelings of sexual pleasures in females during sexual intercourse.

Internal reproductive parts

The vagina is the topmost part of the internal reproductive parts (Figure 3). It extends from vaginal opening, under the labia and below the urethra, as open muscular tube to the female uterus. Vagina performs three important functions including:

At the end of vagina towards the uterus is a small thick wall, the cervix, that connects vagina to the uterus. Cervix also act as a narrow neck, wall or tube for proper movement of sperms to uterus. During childbirth, narrow neck of cervix expands and allows easy passage of fetus towards vagina. Uterus starts from the inner end of cervix and look like upside-down pear. In female reproductive system, uterus is a part where the process of whole fetus development from zygote completes. The walls of uterus are thick and muscular. Its size is equal to lemon in unpregnant women and can increase to a watermelon during pregnancy.

Small tubes called fallopian tubes are present on both sides of the upper corners of uterus. Fallopian tubes connect uterus to female ovaries and provide a passage for fertilization and transportation of egg. On both sides of the uterus are an oval-shaped ovaries that are attached to the fallopian tubes. Ovaries produce, store and release egg through process of ovulation. Besides, ovaries also produce female sex hormones, the estrogen and progesterone.

How do eggs produce?

At the time of birth, baby girls have thousands of eggs present in ovaries which remain inactive until puberty. In females, the age of puberty can be in between 8-13 years. During puberty, production of sex hormones starts which result in sexual maturity in females. In around 13-15 years of females, inactive eggs present in ovaries starts becoming active and mature through developmental processes. Each month ovaries release only one egg. The mature egg transfer into the fallopian tube and fertilize with the sperm (if present) to form zygote.

How babies form?

Fertilization takes place in the fallopian tubes is the first step in formation of newborn babies. In this process, male sperms fuse with female egg and form zygote which is also called fertilized egg. At any given time, only one sperm and one egg can fuse together. As fusion occurs, such changes occur in protein coating of the egg cell that prevent entry of other sperms into the egg. It is this step which decides whether a newborn baby is girl, or a boy. By birth males have two types of genes, X and Y. While females have only X genes. Therefore, a newborn baby will be a girl if sperm with X-gene fuse with the egg during fertilization. On the contrary, a newborn baby will be a boy if sperm with Y-gene fuse with the egg during fertilization.

After fertilization, zygote remains in the fallopian tubes for 3-4 days and rapidly divides and forms blastocyst within 5-6 days. The blastocyst moves from fallopian tubes into the uterus where it attaches itself to the lining of the uterus walls. Its outer thick walls implant into the uterus and form placenta. This stage is called implantation. Some placental cells develop and form a double layer membrane called amniotic sac around the blastocyst. Those blastocysts that have amniotic sac around them are called embryo, thus, embryonic stage starts afterwards amniotic sac is filled with amniotic fluid in which developing embryo floats. The blastocyst stage remains until approximately 3^rd week of fertilization while 5^th week of pregnancy. It’s because doctors count pregnancy from first day of last menstrual cycle while fertilization occurs in mid of menstrual cycle.

Embryonic stage

In embryonic stage, formation of body organs starts in which embryo elongate and form a human shape. First of all, formation of brain and spinal cord tissues start. Later alongside them, formation of other body organs such as heart, blood vessels, stomach, intestine, muscles and skin cells also start. In 12^th week of pregnancy, the formation of all body organs except brain and spinal cord is completed. That’s why, chances of birth defects are high in this time period. Doctors prevent pregnant females to take different medicines, radiations and vaccines because developing embryo is sensitive to such things.

In 10^th week of pregnancy, embryonic stage ends, and the developing embryo is considered fetus. The formation of umbilical cord also occurs in this time period. Umbilical cord is essential for exchange of oxygen, nutrients and waste materials between placenta and fetus. In fetus development stage, growth and development of those organs and structures occur that form during embryonic stage.

In 12^th to 14^th week of pregnancy, fetus grows and completely fills the uterus. Sex determination of fetus can occur at this stage.

In 16^th to 20^th week of pregnancy, fetus development reaches a stage in which pregnant women can feel fetus movement. While 24^th week of pregnancy is that stage of fetus development in which fetus can survive outside the uterus. However, maturation of lungs continues till delivery while development of brain continues during pregnancy and till first year of birth.

Delivery

Delivery mostly occurs in between 37^th to 42^nd week of pregnancy. During delivery, the membrane of amniotic sac breaks, and baby’s head puts pressure on head of the cervix. The pituitary glands start producing oxytocin hormone that contracts the walls of uterus to ease the delivery step. At the time of birth, a healthy baby weighs around 7 pounds and has 20 inches length.