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D3.1.13 (HL)—Puberty control

Puberty is initiated by increased GnRH from the hypothalamus, which promotes LH release and increased sex hormone production by gonads.

Syllabus
First assessment 2025
Objective
D3.1.13
Level
HL

Exam analysis

Chance of appearing1%of analysed past papers
Latest appearanceMay 2025
Most common paperPaper1A
Typical marks1

Common command terms

  • Identify

Recent exam appearances

May 2025Paper1A ["HL"] · TZ132[ 1 ]D3.1.13 (HL)—Puberty control

Coverage 2025–2025 · Updated 16 Jul 2026

Puberty Begins when the Hypothalamus Activates the Reproductive Axis

HL only

hypothalamus increases pulsatile GnRH → anterior pituitary releases FSH and LH → gonads increase gametogenesis and steroid-hormone secretion → reproductive organs mature and secondary sexual characteristics develop

Shared level Testis-dominant response Ovary-dominant response
pituitary gonadotropins FSH supports sperm production; LH stimulates testosterone secretion FSH supports follicle development; LH supports ovulation and ovarian steroid secretion
gonadal steroids testosterone supports reproductive maturation and male-typical secondary traits oestradiol and progesterone support reproductive maturation and female-typical cyclic changes

Sex steroids also influence bone growth, muscle protein synthesis and changes in body composition. Puberty is therefore a coordinated endocrine transition, not a single anatomical event.

FSH and LH operate in all sexes; their names reflect how they were first studied, not hormones found only in ovaries.

Puberty Activates Two Routes to Specialized Haploid Gametes

HL only

GnRH → pituitary FSH and LH → gonadal steroid secretion plus gametogenesis → sexually mature reproductive systems

Question Sperm route Oocyte route
where? seminiferous tubules ovarian follicles
when? continuous from puberty begins before birth; resumes cyclically
how many functional products? four per primary spermatocyte one per primary oocyte
why different? maximize delivery probability concentrate cytoplasm and reserves

Track cell name, chromosome-set number, cytoplasm and timing together. Those four dimensions distinguish the routes more reliably than memorizing isolated stage lists.

Puberty control

HL only

[ 1 ]

What controls the developmental changes during puberty?

I. Increased release of gonadotropin-releasing hormone (GnRH) by the hypothalamus
II. Luteinizing hormone (LH) leading to increased sex hormone production
III. Gonadotropin-releasing hormone (GnRH) triggering the onset of increased luteinizing hormone (LH)

Concept essentials

  • The hypothalamus initiates puberty control through increased GnRH release.
  • GnRH stimulates increased LH secretion from the pituitary.
  • LH promotes increased sex hormone production by the gonads.