Human Reproduction – Key Terms (Vocabulary Flashcards)

Vocabulary flashcards covering key terms from male and female reproductive development, hormonal regulation, the menstrual cycle, pregnancy, and lactation as described in the lecture notes.

Primordial Germ Cells (PGCs)

Embryonic cells that give rise to gametes; differentiate around 3 weeks post-fertilization and migrate from the yolk sac to the genital ridge.

Gametogenesis

Process of forming gametes (sperm or oocytes) from germ cells.

SRY gene

Sex-determining Region on the Y chromosome that initiates testis development in XY individuals.

Testosterone

Steroid hormone produced by Leydig cells in response to LH; drives male gonad development and secondary sex characteristics.

Androgen Insensitivity Syndrome (AIS)

XY individuals with a defective androgen receptor who develop female-appearing external anatomy despite having testes.

Estrogen (Estradiol, E2)

Primary female sex hormone; produced by granulosa cells via aromatase; dominates the follicular phase and supports the uterine lining.

Progesterone (P4)

Hormone produced by the corpus luteum; dominates the luteal/secretory phase; supports endometrium and pregnancy.

Sertoli cells

Testicular cells that nurture spermatogenesis; respond to FSH and secrete inhibin and ABP.

Leydig cells

Interstitial testicular cells that respond to LH and produce testosterone.

Androgen Binding Protein (ABP)

Protein from Sertoli cells that binds testosterone to concentrate it in the seminiferous tubules.

FSH (Follicle-Stimulating Hormone)

Gonadotropin that stimulates Sertoli cells and spermatogenesis; promotes aromatase activity in granulosa cells.

LH (Luteinizing Hormone)

Gonadotropin that stimulates Leydig cells to produce testosterone; triggers ovulation in females.

Gonadotropin-Releasing Hormone (GnRH)

Hypothalamic hormone that stimulates the anterior pituitary to secrete LH and FSH; must be released in a pulsatile fashion.

Negative feedback

Regulatory mechanism where androgens inhibit GnRH/LH/FSH and inhibin inhibits FSH to maintain hormone balance.

Inhibin

Sertoli cell–secreted protein that inhibits FSH release from the anterior pituitary.

Meiosis I

Reduction division in which homologous chromosomes separate, producing two haploid cells.

Meiosis II

Equational division in which sister chromatids separate, producing four haploid gametes.

Spermatogonia

Diploid germ cells in the seminiferous tubules that divide mitotically to maintain the germ line and produce spermatocytes.

Sperm (Spermatozoa)

Mature male gametes; haploid 23 chromosomes; produced by spermatogenesis and mature in the epididymis.

Epididymis

Coiled duct where sperm mature and are stored before ejaculation.

Vas Deferens

Ductus that transports sperm from the epididymis to the urethra; site of vasectomy when cut.

Oogonia

Fetal germ cells that proliferate by mitosis to form oogonia, which become primary oocytes.

Oocyte

Immature egg cell; becomes haploid after meiosis I and completes meiosis II only upon fertilization.

Primordial Follicle

Oocyte surrounded by a single layer of squamous granulosa cells; earliest follicle stage.

Granulosa cells

Follicle cells inside the theca; respond to FSH and express aromatase to produce estrogens; become granulosa lutein cells after ovulation.

Theca cells

Outer follicle cells that respond to LH and produce androgen precursors for estrogen synthesis; become theca lutein cells after ovulation.

Aromatase

Enzyme that converts androgens to estrogens within the follicle.

Corpus Luteum

Post-ovulation structure that secretes progesterone (and some estrogen) to support early pregnancy; if no embryo, it degenerates.

LH Surge

Rapid rise in LH driven by estrogen positive feedback that triggers ovulation and corpus luteum formation.

hCG (human chorionic gonadotropin)

Embryo-produced hormone that rescues the corpus luteum from luteolysis to sustain early pregnancy.

Ovarian cycle

Cycle of follicular development and corpus luteum formation in the ovary.

Follicular phase

Ovarian phase with rising estrogen, development of follicles, and ovulation at the end.

Luteal phase

Post-ovulation ovarian phase where the corpus luteum secretes progesterone and estrogen.

Proliferative phase

Uterine phase driven by estrogen, with thickening and growth of the endometrium.

Secretory phase

Uterine phase driven by progesterone (and estrogen) following ovulation; endometrium matures for potential implantation.

Menstruation

shedding of the endometrium when pregnancy does not occur; start of the menstrual cycle.

Ovulation

Release of the oocyte from the dominant follicle, typically triggered by the LH surge.

Endometrium

Lining of the uterus that thickens and becomes glandular in response to ovarian hormones to support pregnancy.

Luteolysis

Degeneration of the corpus luteum when pregnancy does not occur, leading to decreased estrogen/progesterone and menstruation.

Oviduct

Fallopian tube; site of fertilization and transport of oocyte/zygote toward the uterus.

Prolactin

Pituitary hormone that stimulates milk production in the mammary glands.

Oxytocin

Posterior pituitary hormone that stimulates milk ejection and uterine contractions during labor; also involved in bonding.

Milk let-down

Neuroendocrine reflex where tactile stimulation triggers oxytocin release, causing milk ejection from the mammary glands.

Gonadotropin signaling (GPCR-cAMP-PKA)

LH/FSH receptors are GPCRs that activate adenylate cyclase, raise cAMP, activate PKA, and regulate gene expression (e.g., aromatase).