Reproductive Processes

Reproductive Processes

Menstrual Cycle

  • Begins with menstruation, which is the shedding of the uterus lining along with unfertilised eggs.
  • In the follicular phase, follicle-stimulating hormone (FSH) stimulates the ovary to produce around 5 to 20 follicles, each containing its egg.
  • The ovulation phase occurs halfway through the cycle where a mature egg is released due to a surge in luteinising hormone (LH).
  • The final phase is the luteal phase where the ruptured follicle collapses and starts producing progesterone.
  • If the egg is not fertilised, progesterone levels drop and menstruation begins. If the egg is fertilised, the hormonal changes support pregnancy development.

Spermatogenesis

  • Occurs in the testes and is a part of the male reproductive process.
  • Begins with germ cells, which divides into two cells in preparation to form a sperm cell.
  • Go through two division processes; primary spermatocytes divide to create secondary spermatocytes, these then divide into spermatids.
  • These immature cells then develop into mature sperm cells ready for ejaculation.

Fertilisation and Implantation

  • Begins when a sperm successfully penetrates an egg in the fallopian tube – this is known as fertilisation.
  • The fertilised egg, now known as a zygote, begins to divide, forming a ball of cells called a blastocyst.
  • The blastocyst moves down the fallopian tube and implants into the uterus, marking the beginning of pregnancy.

Pregnancy and Development

  • Pregnancy lasts approximately 40 weeks, split into three trimesters.
  • The first trimester encompasses major developmental stages for the organ systems.
  • The second trimester mostly involves the continuous development and growth of the foetus.
  • The third trimester involves further growth and prepares the foetus for survival outside the uterus.

Birth and Postnatal Development

  • Final stage of pregnancy where the infant is delivered from the mother’s body.
  • The three stages of labour are dilation of the cervix, delivery of the infant, and expulsion of the placenta.
  • Postnatal development includes a range of physiological and psychological adjustments for both the newborn and the mother.