Question

Increase in progesterone level is required for ovulation in which species
A. Mare
B. Bitch
C. Cattle
D. Camel
E. Goat
Choose the correct answer from the options given below:

• A. A only
• B. B only
• C. C and D only
• D. A, D and E only

Hint:

Canine Pre-ovulatory Peculiarity: In the BITCH, follicles luteinize BEFORE ovulation, causing Serum Progesterone to rise ($> 2\text{ ng/mL}$) to trigger the LH surge. In other species, progesterone must be basal.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Canine reproductive endocrinology is unique among domestic mammals in exhibiting pre-ovulatory follicular luteinization and elevated serum progesterone prior to the LH surge and ovulation.
Key Formula or Approach:
\[ \text{Pre-ovulatory Bitch: Follicular Luteinization} \longrightarrow \text{Progesterone rises to } 2.0 - 4.0\text{ ng/mL (Triggers LH Surge)} \]

Step 2: Detailed Explanation:
Comparative preovulatory endocrinology:
1. Most Mammals (Cow, Mare, Goat, Camel): Progesterone is synthesized solely by the post-ovulatory corpus luteum. During follicular proestrus/estrus, progesterone levels must drop to basal levels ($< 0.5 - 1.0\text{ ng/mL}$) to permit the preovulatory LH surge. High progesterone strictly blocks ovulation.
2. Canine (Bitch): Uniquely exhibits extensive pre-ovulatory luteinization of mature Graafian follicles prior to rupture. Serum progesterone begins rising above basal ($> 2.0\text{ ng/mL}$) during late proestrus, which exerts a positive feedback effect on the hypothalamus to trigger the preovulatory LH surge and subsequent ovulation (at $4 - 10\text{ ng/mL}$).
Therefore, a mandatory rise in progesterone is required for ovulation in B only (Bitch).

Step 3: Final Answer:
Therefore, an increase in progesterone is required for ovulation in B only, matching option (B).