Grade 12 Life Science: Oogenesis, Folliculogenesis, and Gametogenesis Comparison

Vocabulary practice flashcards covering human gametogenesis, the timeline of oogenesis, ovarian follicle development, meiotic arrests, and comparative characteristics between spermatogenesis and oogenesis based on Al-Mahdi High School Life Science lecture notes.

12EBL (Life Science)

The Grade 12 Life Science academic curriculum at Al-Mahdi Schools covering subjects including Biology, Chemistry, Physics, Mathematics, Philosophy, and Languages.

Oogenesis

The biological process of forming female gametes (ova) within the ovaries and fallopian tube, starting during embryonic life and completing only upon fertilization.

Oogonia ($2n$)

Diploid female germ cells that multiply by mitosis before birth to yield primary oocytes.

Primary Oocyte ($2n$)

A diploid female germ cell formed before birth that initiates meiosis I and arrests at prophase I ($P_I$) until puberty, having the same age as the woman.

Secondary Oocyte ($n$)

A large haploid cell produced from the unequal division of a primary oocyte during meiosis I; it contains most of the cytoplasm, has $23$ chromosomes ($2\text{ chromatids/chromosome}$), and arrests at metaphase II ($M_{II}$).

First Polar Body ($n$)

A small haploid non-functional cell formed alongside the secondary oocyte during the unequal division of meiosis I.

Ovulation

The release of the secondary oocyte (arrested at metaphase II) from the mature Graafian follicle into the peritoneal cavity and fallopian tube, surviving for approximately $24\,\text{h}$ if not fertilized.

Second Polar Body ($n$)

A small haploid cell extruded by the secondary oocyte following the completion of meiosis II upon fertilization in the fallopian tube.

Mature Graafian Follicle

A fully developed ovarian follicle reaching approximately $20\,\text{mm}$ that encloses a secondary oocyte, antrum, granulosa cells, internal and external theca layers, zona pellucida, and corona radiata.

Follicular Cavity (Antrum)

The fluid-filled chamber formed within developing secondary and mature Graafian follicles.

Zona Pellucida

A specialized glycoprotein layer directly surrounding the plasma membrane of the oocyte.

Corona Radiata

The outer layer of granulosa cells directly surrounding the zona pellucida and oocyte.

Cumulus Oophorus

The cluster of follicle cells (granulosa) that anchors and supports the oocyte within the mature Graafian follicle.

Corpus Luteum (Yellow Body)

The glandular structure formed from the ruptured follicle after ovulation; it lasts for $3\text{ months}$ if fertilization occurs, or regresses if fertilization does not take place.

Corpus Albicans (White Body)

The degenerate fibrous scar tissue formed in the ovary following the regression of the corpus luteum in the absence of fertilization.

Spermatogenesis

The continuous process of male gamete formation in the seminiferous tubules of the testes beginning at puberty and taking approximately $74\,\text{days}$.

Gamete Lifespan

The duration of gamete viability: sperm cells survive for $3\text{ to }4\,\text{days}$ in the female genital tract, whereas an unfertilized secondary oocyte survives for approximately $24\,\text{hours}$ after ovulation.

Meiotic Arrests in Oogenesis

The two developmental pauses in female meiosis: the first arrest at prophase I ($P_I$) during fetal life until puberty, and the second arrest at metaphase II ($M_{II}$) released only by fertilization.

Phases of Gametogenesis

The four sequential stages involved in gamete development: multiplication, growth, maturation, and differentiation.