Histological & Histochemical Techniques

• Pathomorphology of Pulmonary Emphysema:
• Characterized by the abnormal, permanent enlargement and overdistension of airspaces distal to the terminal bronchioles, accompanied by destructive rupture of alveolar septal walls.
• Loss of alveolar surface area and elastic recoil leads to air trapping, expiratory dyspnea, and formation of subpleural bullae (bullous emphysema) or dissection of air into interlobular septa (interstitial emphysema common in cattle due to lack of collateral ventilation).
• nalysis:
• (Overdistension of alveoli with rupture of alveolar walls): Correct definition.

Correct option: (2) Overdistension of alveoli with rupture of alveolar walls

• Enzymatic Degradation of Catecholamines and COMT Inhibition:
• Catechol-O-Methyltransferase (COMT) catalyzes the transfer of a methyl group from S-adenosylmethionine to a hydroxyl group of catecholamines (dopamine, epinephrine, norepinephrine) and levodopa.
• Entacapone (and Tolcapone) is a selective, reversible COMT inhibitor used in neuropharmacology to prevent peripheral breakdown of levodopa, increasing central dopamine availability.
• Selegiline and Rasagiline are MAO-B inhibitors; Clorgyline is a MAO-A inhibitor.
• nalysis:
• (Entacapone): Correct COMT inhibitor.

Correct option: (3) Entacapone

• Equine Mating Behavior:
• Courtship (vocalizing, nuzzling, flehmen, sniffing the mare's flank) is followed by mounting.
• The actual act of mounting, penile insertion (intromission), pelvic thrusts, and ejaculation in horses is rapid, typically lasting approximately $30 - 40\text{ seconds}$ (about 40 seconds), indicated by rhythmic "tail flagging" in the stallion during ejaculation.
• nalysis:
• (About 40 sec): Correct standard copulatory duration.

Correct option: (1) About 40 sec

• Neonatal Hypothermia Pathophysiology:
• Assertion (A): Hypothermia is a major cause of perinatal mortality in newborn calves, lambs, and piglets. (True).
• Reason (R): Neonates possess an immature, poorly integrated hypothalamic thermoregulatory center, combined with a large surface-area-to-body-mass ratio, wet hair coat at birth, and minimal subcutaneous adipose reserves. They are unable to maintain homeothermic body core temperature in cold ambient environments. (True).
• nalysis:
• Both (A) and (R) are true, and (R) provides the physiological explanation for (A). Hence, Option 1 is correct.