Reproductive System: Gametogenesis, Hormones, and Pathways

**Site of Sperm Formation

Seminiferous tubules of the testes**

**Site of Egg Formation

Ovarian follicles in the ovaries**

**Oogenesis

Egg production process beginning before birth; produces one functional ovum and polar bodies**

**Spermatogenesis

Continuous sperm production beginning at puberty; produces four functional sperm per primary spermatocyte**

**Primary Oocyte

Cell arrested in prophase I before birth**

**Secondary Oocyte

Cell released at ovulation; completes meiosis II only if fertilized**

**Polar Bodies

Small nonfunctional cells produced during oogenesis**

**Spermatogonia

Stem cells in testes that divide to form sperm**

**Primary Spermatocyte

Cell entering meiosis I**

**Secondary Spermatocyte

Cell entering meiosis II**

**Spermatid

Haploid cell that matures into sperm**

**Spermiogenesis

Final maturation process converting spermatids into sperm**

**Ovulation

Release of secondary oocyte from Graafian follicle triggered by LH surge**

**Fertilization

Fusion of sperm and egg in uterine tube within ~24 hours of ovulation**

**Zona Pellucida

Protective glycoprotein layer around oocyte penetrated by sperm**

**Corona Radiata

Outer layer of follicle cells surrounding oocyte**

**Zygote

First diploid cell formed after fertilization**

**Implantation

Blastocyst embedding into endometrium about 6-7 days after fertilization**

**Blastocyst

Early embryo consisting of inner cell mass and trophoblast**

**Corpus Luteum

Structure formed after ovulation that secretes progesterone and estrogen**

**Progesterone

Hormone maintaining endometrium for implantation**

**Pathway of Sperm

Seminiferous tubules → straight tubules → rete testis → efferent ductules → epididymis → ductus deferens → ejaculatory duct → prostatic urethra → membranous urethra → spongy urethra → external urethral orifice**

**Epididymis

Site of sperm maturation and storage**

**Ductus Deferens

Tube transporting sperm during ejaculation**

**Ejaculatory Duct

Passage where sperm mixes with seminal vesicle fluid**

**Seminal Vesicles

Produce ~60% of semen; alkaline fluid with fructose, prostaglandins, and coagulating proteins**

**Prostate Gland

Produces milky, slightly acidic fluid with citrate, enzymes, and PSA to activate sperm**

**Bulbourethral Glands

Produce thick mucus that lubricates and neutralizes acidic urine in urethra**

**Semen

Mixture of sperm and glandular secretions that nourish and transport sperm**

**FSH in Females

Stimulates follicle development and estrogen secretion**

**LH in Females

Triggers ovulation and corpus luteum formation**

**Estrogen

Hormone that builds endometrium and regulates feedback on FSH and LH**

**Low/Moderate Estrogen

Negative feedback on FSH and LH**

**High Estrogen (Mid‑Cycle)

Positive feedback causing LH surge and ovulation**

**Progesterone

Hormone from corpus luteum that maintains endometrium and inhibits GnRH, FSH, and LH**

**Inhibin

Hormone that inhibits FSH to prevent multiple follicles from developing**

**Relaxin

Hormone that softens uterus and pelvic ligaments**

**If No Fertilization

Corpus luteum degenerates, hormone levels drop, and menstruation begins**