Structure of Sperm

Topics

Estimated time: 10 minutes

CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12

Introduction

The sperm (spermatozoon, plural: spermatozoa) is the male gamete - a highly specialised, microscopic, and motile cell. Its entire structure is designed with one purpose: to swim to and fertilise the female egg (ovum).

A human sperm is approximately 60 µm long and is completely enveloped by a plasma membrane. Sperms can survive for 3–4 months in the male genital tract, but only 24–48 hours after ejaculation into the female genital tract. During a single ejaculation, approximately 200–300 million sperms are released; however, for normal male fertility, at least 60% must have normal morphology and at least 40% must show vigorous motility.

CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12

Structure of Sperm

Part	Key Components	Primary Function
Head	Haploid nucleus, Acrosome (with hyaluronidase & other hydrolytic enzymes)	Carries paternal genetic material; acrosome enzymes dissolve egg membrane during fertilisation
Neck	Proximal centriole, Distal centriole	Proximal centriole → initiates first cleavage in zygote; Distal centriole → gives rise to axial filament of tail
Middle Piece	Axial filament, Nebenkern (mitochondrial spiral - 10–14 turns), Manchette, Annulus (ring centriole)	Produces ATP energy (via mitochondria) for tail movement and sperm motility
Tail (Flagellum)	Axoneme with 9 + 2 microtubule arrangement, cytoplasmic sheath, plasma membrane (principal piece), end piece	Locomotion - propels sperm toward the egg by whip-like beating

CBSE: Class 12
Maharashtra State Board: Class 12
CISCE: Class 12

Key Points: Structure of Sperms

Part of Sperm	Structure	Major Components	Function
Head	Conical	Haploid nucleus, acrosome	Carries genetic material; enzymes help in fertilization
Neck	Short region	Proximal and distal centrioles	Connects head to tail; initiates zygote division
Middle piece	Cylindrical	Axial filament, mitochondrial sheath	Supplies energy for movement
Tail	Long flagellum	Axial filament, plasma membrane	Locomotion of sperm

Structure of Sperm

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Topics

Reproduction in Lower and Higher Plants

Reproduction in Lower and Higher Animals

Inheritance and Variation

Molecular Basis of Inheritance

Origin and Evolution of Life

Plant Water Relation

Plant Growth and Mineral Nutrition

Respiration and Circulation

Control and Co-ordination

Human Health and Diseases

Human Reproduction

Enhancement of Food Production

Biotechnology

Organisms and Populations

Ecosystems and Energy Flow

Biodiversity, Conservation and Environmental Issues

Introduction