Class 12 Biology - Human Reproduction

Activity 2.1: Study of T.S. of Mammalian Testis and Ovary (Permanent Slides)

Aim: To identify the histological features of mammalian testis and ovary and understand the stages of gametogenesis.

Materials Required:

Compound Microscope (up to 450x magnification)
Permanent slides of T.S. of Mammalian (e.g., Rat or Rabbit) Testis
Permanent slides of T.S. of Mammalian Ovary

Procedure:

Clean the microscope lenses and place the permanent slide of the Testis on the stage.
Observe under low power (10x) to locate the seminiferous tubules.
Switch to high power (40x or 45x) to observe the specific cell types.
Repeat the process for the Ovary slide.

Scientific Note In the testis, look for the Blood-Testis Barrier (BTB) formed by tight junctions between Sertoli cells. This barrier protects developing haploid germ cells from the host's immune system. In the ovary, observe the Antrum (fluid-filled cavity) in the Graafian follicle, which contains high concentrations of Estrogen and Follicular Fluid ( $Liquor\ folliculi$ ).

Observations (Testis):

Seminiferous Tubules: Circular or oval structures lined by germinal epithelium.
Spermatogonia: Large, round cells at the periphery.
Sertoli Cells: Columnar cells providing nourishment (Nurse cells).
Leydig Cells: Found in the interstitial spaces; secrete Testosterone.

Observations (Ovary):

Primary Follicles: Small oocytes surrounded by a single layer of granulosa cells.
Graafian Follicle: Large follicle with a distinct antrum and a secondary oocyte surrounded by the Zona Pellucida.
Corpus Luteum: A yellowish, glandular mass formed after ovulation that secretes Progesterone.

Lab Best Practice When switching to high power, only use the fine adjustment knob to avoid crashing the objective lens into the permanent slide.

Activity 2.2: Study of Human Sperm Smear

Aim: To study the morphology of human sperm and identify its functional regions.

Materials Required:

Permanent slide of a human sperm smear
Oil immersion lens (100x) and Immersion oil
Microscope

Procedure:

Focus the sperm smear under 40x.
Add a small drop of immersion oil onto the coverslip.
Carefully rotate the 100x objective into place and focus using the fine adjustment.

Scientific Note The Acrosome at the tip of the sperm head is a modified lysosome containing proteolytic enzymes like Hyaluronidase and Acrosin (Zona lysin), which are essential for penetrating the egg's protective layers during fertilization. The middle piece is packed with Mitochondria (organized as the Nebenkern spiral) that generate ATP for flagellar motility.

Observation:

Head: Contains the haploid nucleus and acrosome.
Neck: Very short; contains two centrioles.
Middle Piece: Contains the mitochondrial spiral.
Tail: Long, whip-like structure for locomotion.

Safety First Always handle permanent slides by the edges. If using fresh smears (university level), treat all biological fluids as potential biohazards and follow strict sterilization protocols using 10% bleach for disposal.

Class 12 Biology - Human Reproduction

Activity 2.1: Study of T.S. of Mammalian Testis and Ovary (Permanent Slides)

Aim: To identify the histological features of mammalian testis and ovary and understand the stages of gametogenesis.

Materials Required:

Compound Microscope (up to 450x magnification)
Permanent slides of T.S. of Mammalian (e.g., Rat or Rabbit) Testis
Permanent slides of T.S. of Mammalian Ovary

Procedure:

Clean the microscope lenses and place the permanent slide of the Testis on the stage.
Observe under low power (10x) to locate the seminiferous tubules.
Switch to high power (40x or 45x) to observe the specific cell types.
Repeat the process for the Ovary slide.

Observations (Testis):

Seminiferous Tubules: Circular or oval structures lined by germinal epithelium.
Spermatogonia: Large, round cells at the periphery.
Sertoli Cells: Columnar cells providing nourishment (Nurse cells).
Leydig Cells: Found in the interstitial spaces; secrete Testosterone.

Observations (Ovary):

Primary Follicles: Small oocytes surrounded by a single layer of granulosa cells.
Graafian Follicle: Large follicle with a distinct antrum and a secondary oocyte surrounded by the Zona Pellucida.
Corpus Luteum: A yellowish, glandular mass formed after ovulation that secretes Progesterone.

Lab Best Practice When switching to high power, only use the fine adjustment knob to avoid crashing the objective lens into the permanent slide.

Activity 2.2: Study of Human Sperm Smear

Aim: To study the morphology of human sperm and identify its functional regions.

Materials Required:

Permanent slide of a human sperm smear
Oil immersion lens (100x) and Immersion oil
Microscope

Procedure:

Focus the sperm smear under 40x.
Add a small drop of immersion oil onto the coverslip.
Carefully rotate the 100x objective into place and focus using the fine adjustment.

Observation:

Head: Contains the haploid nucleus and acrosome.
Neck: Very short; contains two centrioles.
Middle Piece: Contains the mitochondrial spiral.
Tail: Long, whip-like structure for locomotion.

Class 12 Biology - Human Reproduction (Activities)

Class 12 Biology - Human Reproduction

Activity 2.1: Study of T.S. of Mammalian Testis and Ovary (Permanent Slides)

Activity 2.2: Study of Human Sperm Smear

On this page

Class 12 Biology - Human Reproduction (Activities)

Class 12 Biology - Human Reproduction

Activity 2.1: Study of T.S. of Mammalian Testis and Ovary (Permanent Slides)

Activity 2.2: Study of Human Sperm Smear

On this page