Chapter:3

What are Human Reproduction?

The Male Reproductive System

It consists of the primary sex organs (a pair of testes):

  • Scrotum โ€“ a pouch in which testes are situated
  • Testicular lobules
  • Seminiferous tubules โ€“ contains Spermatogonia and Sertoli cells- contains Leydig cells

Accessory Ducts

  • ➥ Rete testis
  • ➥ Vasa efferentia
  • ➥ Epididymis
  • ➥ Vas deferens
  • ➥ Urethra

Accessory Glands

  • ➥ A pair of seminal vesicles
  • ➥ Prostate gland
  • ➥ Bulbourethral gland

These glands secrete seminal plasma rich in fructose, calcium and certain enzymes. Secretions of bulbourethral glands also help in lubrication of penis.

External Genitalia

  • The penis is the external genitalia in human males.
  • It is made up of special erectile tissue that helps in erection of the penis to facilitate insemination.
  • The enlarged tip of the penis is called glans penis covered by foreskin.

The Female Reproductive System

It consists of the primary sex organ that is a pair of ovaries.

  • Secondary sex organs- the duct system consisting of a pair of fallopian tube , a uterus , cervix and vagina
  • External genitalia
  • Mammary glands

Ovaries

  • ➥ Produce female gametes called ova.
  • ➥ Covered by a thin epithelium, enclosing the ovarian stroma.
  • ➥ Stroma is divided into 2 regions i.e. Cortex (outer) and Medulla (inner).

Gametogenesis

The process of formation of gametes is called gametogenesis. It is of two types:

Spermatogenesis in males

The process of formation of sperms in males is called spermatogenesis

Oogenesis in females

The process of formation of a mature female gamete is called oogenesis

Structure of sperm composed of head, neck, middle piece and a tail.

Menstrual Cycle

The cyclic changes that occur in the reproductive organs of primate females is called menstrual cycle

The events in a menstrual cycle can be studied under four phases:

  • Menstrual Phase
  • Follicular Phase
  • Ovulatory Phase
  • Luteal Phase

Fertilization

The process of fusion of a sperm with an ovum is called fertilization.

Implantation

  • Zygote moves towards uterus โ†’ Blastomeres (2, 4, 8,16 daughter cells) โ†’ morula (8-16 blastomeres) โ†’ Blastocyst
  • Blastocyst gets embedded in ndometrium of uterus.

Pregnancy And Embryonic Development

  • Placenta secretes hormones like hCG, hPL, estrogens, progesterones (to maintain pregnancy).
  • Inner cell mass differentiates into an outer layer called ectoderm, middle mesoderm and an inner layer endoderm.

Parturition

  • Gestation period โ€“ 9 months.
  • Parturition โ€“ the process of delivery of the foetus (childbirth).

Lactation

  • Production of milk towards the end of pregnancy is called lactation.
  • The milk produced during the initial few days is called colostrum that is rich in IgG antibody.