Question

Given below are two statements:
Statement I: Oxytocin is secreted from the hypothalamus in cattle
Statement II: Oxytocin is secreted from the ovary in cattle
In the light of the above statements, choose the most appropriate answer from the options given below

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is correct but Statement II is false
• D. Statement I is incorrect but Statement II is true

Hint:

Oxytocin Sources in Ruminants: 1. Hypothalamus (PVN/SON $\rightarrow$ Neurohypophysis $\rightarrow$ Milk ejection) + 2. Ovary (Corpus Luteum large luteal cells $\rightarrow$ Luteolysis mechanism).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Dual anatomical origin of oxytocin in female ruminants: neuroendocrine synthesis in hypothalamic magnocellular nuclei and nonapeptide synthesis in luteal granulosa cells of the corpus luteum.
Key Formula or Approach:
\[ \text{Neuroendocrine: Hypothalamus (PVN/SON)} \xrightarrow{\text{Post. Pituitary}} \text{Systemic Oxytocin (Milk ejection)} \]
\[ \text{Ovarian: Corpus Luteum (Luteal Cells)} \longrightarrow \text{Luteal Oxytocin (Drives Endometrial } \text{PGF}_{2\alpha} \text{ Luteolysis)} \]

Step 2: Detailed Explanation:
1. Statement I: In cattle, Oxytocin is synthesized by the magnocellular neurons of the Paraventricular (PVN) and Supraoptic (SON) nuclei of the Hypothalamus, transported down unmyelinated axons to the posterior pituitary (neurohypophysis), and released into the bloodstream for milk ejection and parturition. Hence, Statement I is true.
2. Statement II: In ruminants (cows and ewes), the large luteal cells of the ovarian Corpus Luteum (ovary) also synthesize and secrete significant amounts of oxytocin. Luteal oxytocin binds to endometrial oxytocin receptors in late diestrus to stimulate pulsatile releases of prostaglandin $\text{F}_{2\alpha}$ ($\text{PGF}_{2\alpha}$), driving luteal regression (luteolysis). Hence, Statement II is true.

Step 3: Final Answer:
Therefore, Both Statement I and Statement II are true, corresponding to option (A).