A reframing of folliculogenesis built around the 2023 work of Antonia Lamarck and the long-established two-cell two-gonadotrophin model. LH receptor structure and signalling, theca androgen synthesis under LH control, granulosa-cell aromatase under FSH control — and how the LH-FSH symphony shapes follicular competence at each stage.
Follicles are gonadotrophin-dependent throughout development, not only at the antral stage. LH activity is required not just at the ovulatory peak but through late follicular maturation to support steroidogenesis and oocyte competence. LH and FSH act in complementary directions — the same receptor family, distinct cellular targets — and cannot be substituted for one another at full dose.
Re-evaluate FSH-only protocols in patients with low or impaired LH activity, including older patients, LHCGR polymorphism carriers and hypogonadotrophic profiles. Build the protocol decision on a receptor-cell-hormone mental model rather than total gonadotrophin dose.
Two-cell two-gonadotrophin is a model — real cycles add genotype, BMI, age and concurrent endocrine state on top. LH activity and HCG are not interchangeable in every clinical situation; their pharmacokinetics differ.
Are antral follicles really gonadotrophin-dependent only at one stage — or all the way through? A walk through the LH receptor, the two-cell two-gonadotrophin model and what the 2023 reframing of folliculogenesis means for choosing a stimulation protocol.
