Reproduction | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Introduction

The male reproductive system is a complex network of organs working together to produce and deliver sperm for reproduction. The primary players include the testicles, responsible for sperm production, and accessory glands like the vesiculae seminalia and prostate, contributing to semen formation. This system also involves ducts like the vas deferens and the epididymis, ensuring the proper transport of seminal fluid.

Male Reproductive System

Essential Organs:

• Two testicles are the main reproductive glands.
• Ductus deferens carries fluid from the testicles.
• Vesiculae seminalia, prostate, Cowper's glands, and penis are accessory sex glands.

Accessory Sex Glands:

• Vesiculae seminalis, prostate, and Cowper's glands release their substances into the urethra.
• Fluid from these glands mixes with testicle secretions to form semen.

Testicles (Testes):

• Located in the scrotum, a pouch in the prepubic region.
• Oval-shaped and compressed from side to side.
• Weigh about 400 gm in bulls.
• Covered by a peritoneum and a dense fibrous capsule called tunica albuginea.
• Contains seminiferous tubules producing sperm and interstitial tissues secreting male sex hormones.

Epididymis:

• Attached to the posterior border of the testicle.
• Consists of head and tail portions.
• A long coiled tube (30-35 meters) connecting vas deferens and tubule of the testis.
• Head connects to the testicle's ducts, and tail connects to the vas deferens.

Ductus Deferens (Vas Deferens):

• Conducting tube for seminal fluid.
• Extends from the epididymis to the pelvic urethra.
• Passes along the testicle's posterior border, the spermatic cord, under vesiculae seminalis and prostate.
• Opens into the pelvic urethra.
• Contains a well-developed smooth muscle coat for conveying seminal fluid during ejaculation.
• Glands in the duct add secretions to the fluid part of semen.

Seminal Vesicles:

• Paired glands near the bladder, each weighing 60 to 75 gms in bulls.
• Secretions mix with ductus deferens fluid via ejaculatory duct into the urethra.

Prostate Gland:

• Lobulated gland on the bladder's neck and beginning of the urethra.
• Unpaired but has two rows of openings near ejaculatory ducts for secretions into the urethra.

Bulbo Urethral Glands (Cowper's Glands):

• Two glands on either side of the pelvic urethra.
• Ducts discharge viscous secretions into the posterior part of the pelvic urethra.

Penis:

• Male copulatory organ composed of erectile tissue.
• Extends from ischial arch to the abdominal wall, with a curved portion behind the scrotum.
• The glans penis contains the external urethral orifice.

Erectile Tissues:

• Comprises corpus cavernosum penis and corpus cavernosum urethra.
• Erection occurs by blood filling cavernous spaces, facilitating copulation.

Scrotum:

• A pouch carrying testicles and parts of the spermatic cords.
• Sensitive to temperature changes, drawing the testicles close to the body in lower temperatures.

Female Reproductive System

• Two organs inside the body cavity, producing eggs or ova.
• Connected to the uterus through fallopian tubes.

Fallopian Tubes (Oviducts):

• Two tubes protruding from each uterine horn.
• Funnel-shaped openings around ovulation guide eggs into the uterus.

Uterus:

• Receives eggs from the fallopian tubes.
• Eggs, though small, are larger than sperm and enter the uterus, not the body cavity.

Other Structures:

• Cervix, Vagina, and Vulva complete the female reproductive system.
• These structures play crucial roles in the reproductive process, including fertilization and childbirth.

Uterus Structure:

• Consists of two horns and a body in cows and ruminants.
• Contains cotyledons, enlarged during pregnancy, where embryo attaches and gets nourished.
• Rich in glands producing fluid for sperm ascent and egg fertilization.

Cervix, Vagina, and Vulva:

• Uterus ends in the cervix, connecting to the vagina and vulva (external opening).
• Cervix state varies with species and reproductive stage.
• Insemination tube can pass through the cervix during estrus (heat) in cows.

Reproductive Cycle:

• Ovaries start functioning at puberty, exhibiting a rhythmic cycle called estrus or heat.
• Heat period lasts about 19 hours, with an interval of approximately 20 days between cycles.

Ovary Function and Egg Production:

• Ovarian surface contains around 75,000 potential egg-forming cells.
• As heat approaches, a few eggs mature in small follicles on the ovary's surface.
• Mature follicle ruptures after heat, releasing eggs into the tube leading to the uterus.

Fertilization and Yellow Body Formation:

• Fertilization with sperm occurs in the tube; the egg then moves into the uterus.
• The follicle's inner surface transforms into the yellow body (Corpus Luteum) after egg release.
• If conception happens, the yellow body persists during pregnancy, producing hormones.
• Early removal of the yellow body leads to abortion.

Hormonal Regulation:

• The yellow body hormone prevents further egg production or signs of heat if conception occurs.
• If mating fails during heat, the yellow body regresses, becoming smaller and inactive.
• Egg-producing activity restarts in the same or the other ovary if conception doesn't occur.