Human Reproduction Class 12 Notes Biology Chapter 3 - CBSE

Chapter:3

What are Human Reproduction?

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The Male Reproductive System

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

Scrotum – a pouch in which testes are situated
Testicular lobules
Seminiferous tubules – 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	Oogenesis in females
The process of formation of sperms in males is called spermatogenesis	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 → Blastomeres (2, 4, 8,16 daughter cells) → morula (8-16 blastomeres) → 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 – 9 months.
Parturition – 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.

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