Q. 101 Glycoprotein hormones, hCG and eCG, are synthesized in women and mares respectively, during
pregnancy. Both of these chorionic gonadotropin hormones
(A) have only LH-like activity in their respective species.
(B) have only FSH-like activity in other species.
(C) are biologically inactive in other species.
(D) are routinely employed to promote final stages of follicular maturation, ovulation and to treat infertility
in women

This article dives into the roles of chorionic gonadotropins like hCG (human chorionic gonadotropin) and eCG (equine chorionic gonadotropin) in pregnancy, their species-specific activities, and clinical applications. Perfect for biology students, researchers in reproductive endocrinology, and those prepping for exams like NEET PG or CSIR NET.

The Question at a Glance

Glycoprotein hormones, hCG and eCG, are synthesized in women and mares respectively, during pregnancy. Both of these chorionic gonadotropin hormones
(A) have only LH-like activity in their respective species.
(B) have only FSH-like activity in other species.
(C) are biologically inactive in other species.
(D) are routinely employed to promote final stages of follicular maturation, ovulation and to treat infertility in women.

Correct Answer: D
hCG and eCG drive key reproductive processes and are widely used in human fertility treatments, making option D the precise fit.

Why Option D is Correct: Clinical Powerhouse in Fertility

Human chorionic gonadotropin (hCG), produced by the placenta in pregnant women, and equine chorionic gonadotropin (eCG, formerly PMSG), secreted by endometrial cups in pregnant mares, belong to the glycoprotein hormone family. These share structural similarities with luteinizing hormone (LH) and follicle-stimulating hormone (FSH), featuring alpha and beta subunits.

Both hormones excel at mimicking LH to trigger final follicular maturation, ovulation, and corpus luteum formation. In clinical practice:

• hCG is a staple in assisted reproductive technologies (ART) like IVF. Injections (e.g., 5,000–10,000 IU) induce ovulation 36–40 hours post-administration by surging LH-like activity.

• eCG crosses species barriers effectively in humans and livestock, often combined with hCG in protocols to superovulate animals or support human infertility treatments.

This routine use in women for infertility—backed by guidelines from ASRM (American Society for Reproductive Medicine)—confirms D as correct. For instance, hCG triggers the LH surge absent in anovulatory cycles.

Option A Breakdown: LH-Like, But Not “Only”

hCG primarily shows LH-like activity in humans, binding LH/CG receptors to support progesterone production and maintain pregnancy. eCG does the same in mares.

However, both exhibit dual activity:

• LH-like (beta-subunit homology drives ovulation).

• FSH-like (eCG especially, due to its longer half-life and affinity for FSH receptors in non-equine species).

A fails because it ignores FSH-like effects, particularly eCG’s cross-species FSH potency used in veterinary superovulation.

Option B Breakdown: FSH Activity is Real, But Not Exclusive or Limited to “Other Species”

eCG has strong FSH-like activity in non-equine species (e.g., cows, sheep, humans), promoting follicular growth. hCG shows milder FSH-like effects.

Yet B is wrong on two counts:

• Neither has “only” FSH-like activity.

• hCG’s primary LH-like role shines in its own species (humans), not just “other species.”

This misrepresents their broad-spectrum actions.

Option C Breakdown: Far From Inactive Across Species

Both are highly active interspecies:

• hCG works seamlessly in humans and primates.

• eCG’s FSH/LH duality makes it a veterinary workhorse for inducing multiple ovulations in cattle and pigs.

Inactivity would render them useless in fertility clinics—yet hCG sales exceed millions of doses yearly for human use.

Deeper Dive: Structure, Synthesis, and Research Relevance

hCG and eCG arise during pregnancy:

• hCG: Syncytiotrophoblast cells in human placenta (detectable via urine tests from week 4).

• eCG: Specialized endometrial cups in mares (days 40–140 of gestation).

Their carbohydrate-rich structure prolongs half-life (hCG: 24–36 hours; eCG: 4–5 days), enhancing bioactivity. In molecular biology terms, beta-subunit differences dictate receptor specificity—crucial for biotech applications like recombinant hCG production.

For students in genetics or biochemistry, note evolutionary conservation: These hormones highlight glycoprotein evolution, with implications for studying receptor signaling (cAMP pathway) and genetic disorders like hypogonadotropic hypogonadism.

Quick Comparison Table

SEO Tips for Related Searches

Searching “hCG eCG LH FSH activity” or “chorionic gonadotropin infertility treatment”? This Q.101-style question appears in exams testing reproductive physiology. Master it alongside topics like GnRH analogs or ovarian hyperstimulation syndrome (OHSS).