Couples may be helped by medical professionals to conceive using various technologies known together as Assisted Reproductive Technologies (ARTs). Every couple has a unique need which is assessed together by one or more of their reproductive endocrinologists, embryologists, andrologists and gynecologists.
Intrauterine Inseminations (IUI)
IUI includes introduction of donor or partner’s sperms directly into the uterus. In other rarer methods of artificial insemination, the sperms may also be introduced into the cervix or the fallopian tubes. IUI is indicated for donor sperms, unexplained infertility, endometriosis, mild male factor infertility, or cervical factor infertility.
In Vitro Fertilization (IVF)
In Vitro Maturation (IVM)
Frozen Embryo Transfer (FET)
FET involves freezing of the blastocysts from the IVF, and transfer after thawing. FET is indicated in cases of OHSS, other uterine abnormalities identified or complications during the processes, low endometrial receptivity/elevated progesterone or Preimplantation genetic screening. It may also be useful in cases of transfer of one fresh blastocyst, and freezing the others for future cycles.
Testicles (aka. testes, sing. testis) are male sexual glands, are usually present as a pair, oval in shape and produce the male sexual hormone testosterone as well as the sperms (aka. sperm cells or spermatozoa). Testicles reside in scrotum, which is a sac of skin that hangs below the penis. For normal sperm development, the temperature of scrotum and testicles is slightly lower than the body temperature.
Sperms are the male reproductive cells (aka. male gametes). They are produced in the seminiferous tubules of the testes and the entire process takes around 3 months. Mature sperms have a head, a neck and a tail (aka. flagellum) region. The head comprises of the cell body and the acrosome.
While the acrosome is fluid filled flattened sac containing enzymes to help the sperm penetrate the female gamete, the cell body houses the nucleus with the highly condensed DNA (deoxyribonucleic acid) which is the genetic information that the parent passes on to the offspring.
The tail is the longest part of the sperm and gives the sperms motility. The energy for movement of the tail comes from mitochondria (sing. mitochondrion) in the sperm neck.
Upon ejaculation during masturbation or copulation, normally 200 to 300 million sperms are released in the semen. The sperms are transported from the testes to the penis through a pair of tubes called vas deferens. Semen, besides sperms, contains seminal plasma – fluids from the seminal vesicles, the prostate, and the bulbourethral glands.
The external parts of the female reproductive tract, called vulva open into the vagina, which is a muscular canal leading into the lower part of the uterus called cervix.
Ovaries are the female sexual glands, present in the pelvic cavity, that produce oocytes (female reproductive cells) and the female sexual hormones estrogens and progesterone. These hormones together promote sexual development during puberty and the general female sexual health, including the menstrual cycle.
Fallopian tubes and uterus form the other two major internal sexual organs. Fallopian tubes are a pair of tubes leading from the ovaries to the uterus, while the latter is a pear shaped muscular organ and provides protection, nourishment and waste removal for the embryo (w.1 – 8) and the fetus (w.9 – delivery).
At puberty, the ovaries contain approximately 400,000 spheroids of cells called follicles. During ovulation, midway of a menstrual cycle, one of the several developing follicles ruptures to release an oocyte into the fallopian tube. The oocyte is surrounded by a cluster of cells called cumulus cells that help the oocyte mature. The oocyte travels through the fallopian tube towards the uterus.
During orgasm, the male partner ejaculates the semen into the vagina of the female partner. At this stage, semen is thick and viscous, to protect sperms from the acidic environment of the vagina. The most motile sperms begin to travel through the cervical mucus into the uterus, leaving the seminal plasma behind. During ovulation, the barrier of the cervical mucus becomes thinner, and the pH of this environment becomes more favorable for the sperms. The sperms are transported up into the uterus towards the fallopian tubes due to contractile motion of the uterus.
As the sperms traverse through the uterus, they become biochemically capacitated due to the uterine chemical environment. As a result, the sperms show hyperactivity, and begin to undergo acrosome reaction, wherein the acrosome starts releasing its fluid components. The sperms are also attracted towards the oocyte due to chemical attraction known as chemotaxis.
Before the sperms reach the oocyte, they must first bind to the thin layer of cumulus cells outside the oocyte called corona radiata, and then to the glycoproteinaceous layer called zona pellucida (ZP). Upon binding to ZP, the acrosome reaction is triggered and the acrosome bursts, releasing the enzymes to facilitate penetration by the sperms. The enzymes also modify the ZP and harden it to prevent additional sperms to penetrate the ZP.
The sperms that reach the oocyte must bind to the JUNO protein in the oocyte membrane through the IZUMO1 protein in the sperm membrane. At this point, the oocyte immediately sheds away the JUNO from its membrane to prevent any more sperms from binding to it.
In the next step, sperm head and the oocyte fuse together and the sperm DNA is released into the oocyte. This is known as fertilization, and the zygote is formed.
The zygote matures into a multiple cell cluster called blastocyst over days, the ZP layer cracks open (zona hatching), and at around day 9 from ovulation, the embryo implants into the uterus.
