Gametogenesis & Spermatogenesis Lecture

Vocabulary flashcards covering key terms related to germ-cell origin, migration, spermatogenesis regulation, cellular stages, hormonal control, sperm structure, and clinical aspects.

Gametogenesis

The process by which diploid cells undergo meiosis to form haploid gametes (sperm or eggs).

Primordial Germ Cells (PGCs)

Early germ-line cells that arise in the yolk-sac wall, migrate to the genital ridge, and give rise to gametes.

Genital Ridge

Embryonic tissue along the posterior body wall that, together with arriving germ cells, develops into the gonad.

Teratoma

A pluripotent germ-cell tumor that can contain diverse, fully differentiated tissues when a PGC migrates to the wrong location.

Spermatogenesis

Entire process in the testis that produces sperm: mitotic renewal, two meiotic divisions, and maturation.

Spermiogenesis

Morphological transformation of spermatids into mature sperm (cytoplasm removal, DNA condensation, tail addition).

Spermiation

Final step that breaks Sertoli–sperm connections, releasing mature spermatozoa into the seminiferous-tubule lumen.

Spermatogonium

Stem cell descendant of PGCs; divides mitotically to self-renew or form primary spermatocytes.

Primary Spermatocyte

Diploid germ cell that enters and completes meiosis I to create two secondary spermatocytes.

Secondary Spermatocyte

Haploid product of meiosis I; undergoes meiosis II to form spermatids.

Spermatid

Haploid cell formed after meiosis II; non-dividing precursor that undergoes spermiogenesis.

Sertoli Cell

Large nurse cell inside seminiferous tubules that supports, nourishes, and structurally organizes developing sperm.

Leydig Cell

Interstitial testicular cell stimulated by LH to secrete testosterone.

Gonadotropin-Releasing Hormone (GnRH)

Hypothalamic hormone that triggers pituitary release of LH and FSH at puberty.

Luteinizing Hormone (LH)

Pituitary hormone that stimulates Leydig cells to produce testosterone.

Follicle-Stimulating Hormone (FSH)

Pituitary hormone acting on Sertoli cells (with testosterone) to initiate and maintain spermatogenesis.

Testosterone

Steroid hormone inducing primary sex traits (testis growth, sperm production) and male secondary sex characteristics.

Acrosome

Enzyme-filled vesicle capping the sperm head; derived from the Golgi and essential for egg penetration.

Protamines

Small, arginine-rich proteins that replace histones, allowing extreme DNA condensation in sperm heads.

Capacitation

Final functional maturation that occurs in the female reproductive tract, priming sperm for the acrosome reaction.

Seminiferous Tubule

Coiled tubular structure in the testis where germ cells progress from the basal layer to the lumen as they mature.

Cytoplasmic Bridge

Channel left by incomplete cytokinesis connecting germ cells, permitting sharing of cytoplasmic materials.

Syncytium (in Testis)

Network of developing germ cells connected by cytoplasmic bridges and associated with Sertoli cells.

Epididymis

Duct atop the testis where sperm complete maturation and are stored until ejaculation.

Vas Deferens

Muscular duct conveying sperm from the epididymis to the urethra during ejaculation.

Semen

Ejaculate mixture of sperm plus secretions from seminal vesicles and prostate gland.

Primary Sex Traits

Anatomical structures directly involved in reproduction (e.g., testes, penis, spermatogenesis).

Secondary Sex Traits

Non-reproductive male characteristics induced by testosterone, such as facial hair and voice deepening.

In Vitro Fertilization (IVF)

Assisted reproduction technique in which eggs are fertilized by sperm outside the body.

Intracytoplasmic Sperm Injection (ICSI)

IVF method where a single sperm is injected directly into an egg, bypassing capacitation.

Meiosis I

First meiotic division that halves chromosome number, producing secondary spermatocytes.

Meiosis II

Second meiotic division that separates sister chromatids, forming spermatids.

Menopause

Cessation of female monthly cycles around age 50, ending natural ovulation and fertility.